• Decrease font size
  • Return font size to normal
  • Increase font size
U.S. Department of Health and Human Services

Food

  • Print
  • Share
  • E-mail

Pasteurized Milk Ordinance 2005: Appendix I. Pasteurization Equipment and Controls - Tests


Return to Table of Contents
 

I. TESTING APPARATUS SPECIFICATIONS

TEST THERMOMETER

Type:

  1. Mercury or Non toxic Liquid in Glass Actuated: Readily cleanable; plain front; enameled back; length at least 30.5 centimeters (12 inches); immersion point to be etched on stem and mercury or non-toxic liquid to stand in contraction chamber at 0°C (32°F). Non-toxic liquid-in-glass-actuated thermometers must have accuracy and reliability equivalent to mercury thermometers.

    Scale Range: At least 7°C (12°F) below and 7°C (12°F) above the pasteurization temperature at which the operating thermometer is used, with extensions of the scale on either side permitted and protected against damage at 149°C (300°F).

    Temperature Represented by Smallest Scale Division: 0.1°C (0.2°F).

    Number of Degrees per 25 Millimeters (1 inch) of Scale: Not more than four (4) Celsius degrees or not more than six (6) Fahrenheit degrees.

    Accuracy: Within ± 0.1°C (± 0.2°F), throughout specified scale range. The accuracy shall be checked against a thermometer, which has been tested by the National Institute of Standards and Technology (NIST).

    Bulb: Corning normal or equally suitable thermometric glass.

    Case: Suitable to provide protection during transit and periods when not in use.

  2. Digital Test Thermometer: Hand-held; high accuracy digital thermometer; and battery or AC line powered. Calibration is protected from unauthorized changes.

    Range: -18°C to 149°C (0°F to 300°F); Temperature represented by smallest scale division, 0.01°C or °F and digital display.

    Accuracy: System accuracy of: ± 0.056°C (± 0.100°F); Probe accuracy of: ± 0.05°C (± 0.09°F); Repeatability of ± 0.005°C (± 0.009°F); Three (3) month stability: ± 0.025°C (± 0.045°F). Thermometer accuracy from 0°C to 150°C (32°F to 302°F): ± 0.05°C (± 0.09°F). Calibration uncertainty: ± 0.0047°C (± 0.00846°F). The accuracy shall be checked against a thermometer, which has been tested by NIST. A certificate of calibration shall be maintained with the unit.

    Self-Diagnostic Circuitry: Circuitry shall provide constant monitoring of all sensing, input and conditioning circuits. The diagnostic circuitry should be capable of identifying the probe and its calibration information. Without a correct connection of the probe, the display shall alert the operator and no temperature will be displayed.

    Electromagnetic Compatibility: Shall be documented for these devices for their intended use and available to the Regulatory Agency. Units to be used in the "field" shall have been tested for heavy industrial standards, as specified in the European Electromagnetic Compatibility Directive.

    Immersion: Minimum immersion point shall be marked on the probe. During control tests, the probes shall be immersed to equal depths in a water or oil bath.

    Case: Suitable to provide protection during transit and periods when not in use.
     

GENERAL PURPOSE THERMOMETER

Type: Pocket type.

Scale Range: 1°C (30°F) to 100°C (212°F), with extensions of the scale on either side permitted. Protected against damage at 105°C (220°F).

Temperature Represented by Smallest Scale Division: 1°C (2°F).

Accuracy: Within ± 1°C (± 2°F), throughout the specified scale range. Checked periodically against a known accurate thermometer.

In the case of mercury actuated general-purpose thermometers, the following additional specifications shall apply:

Magnification of Mercury Column: To apparent width of not less than 1.6 millimeter (0.0625 inch).

Number of Degrees per Inch of Scale: Not more than twenty-nine (29) Celsius degrees or not more than fifty-two (52) Fahrenheit degrees.

Case: Metal, provided with a fountain pen clip.

Bulb: Corning normal or equally suitable thermometric glass.
 

ELECTRICAL CONDUCTIVITY MEASURING DEVICES

Type: Manual or automatic.

Conductivity: Capable of detecting change produced by the addition of ten (10) pm of sodium chloride, in water of 100 ppm of hardness.

Electrodes: Standard.

Automatic Instruments: Electric clock, time divisions not over 0.2 of a second.
 

STOPWATCH

Type: Open face, indicating fractional seconds.

Accuracy: Accurate to 0.2 of a second.

Hands: Sweep hand, if applicable, one complete turn every sixty (60) seconds or less.

Scale: Divisions of not over 0.2 of a second.

Crown: Depression of crown or push button starts, stops and resets to zero.
 

back to top

II. TEST PROCEDURES

Equipment and field tests to be performed by the Regulatory Agency are listed and suitably referenced below. The results of tests shall be recorded on suitable forms and filed, as the Regulatory Agency shall direct. (Refer to Appendix M.)
 

TEST 1.
INDICATING THERMOMETERS - TEMPERATURE ACCURACY

Reference: Item 16p (A), (B), (C) and (E)

Application: To all indicating thermometers used for the measurement of milk or milk product temperature during pasteurization or aseptic processing, including airspace thermometers.

Frequency: Upon installation; at least once each three (3) months thereafter; whenever the thermometer has been replaced or the regulatory seal on a digital sensor or a digital control box has been broken.

Criteria: Within ± 0.25°C (± 0.5°F) for pasteurization and aseptic processing thermometers and ± 0.5°C (± 1°F) for airspace thermometers, in a specified scale range. Provided, that on batch pasteurizers used solely for thirty (30) minute pasteurization of milk or milk products at temperatures above 71°C (160°F), indicating thermometers shall be accurate to within ± 0.5°C (± 1°F).

Apparatus:

  1. Test thermometer meeting the specifications cited in Part I of this Appendix;
  2. Water, oil or other suitable media bath and agitator; and
  3. Suitable means of heating the media bath.

Method: Both thermometers exposed to water, oil or other suitable media of uniform temperature. Indicating thermometer reading is compared to the reading of the test thermometer.

Procedure:

  1. Prepare a quantity of water, oil or other suitable media in a bath, by raising the temperature of the media to within 2°C (3°F) of the appropriate pasteurization, or airspace temperature, or aseptic processing temperature.
  2. Stabilize the bath temperature and agitate rapidly.
  3. Continue agitation and insert indicating and test thermometers to indicated immersion point.
  4. Compare both thermometer readings at the temperature within the test range.
  5. Repeat the comparison of readings.
  6. Record the thermometer readings, and the thermometer identification or location.
  7. Install seals as appropriate on sensors and control boxes of digital thermometers.

Corrective Action: Do not run the test if the mercury column has been split or capillary tube is broken. The thermometer should be returned to the factory for repair. When the indicating thermometer differs from the test thermometer by more than 0.25°C (0.5°F) and the airspace thermometer by more than 0.5°C (1°F), the indicating thermometer should be adjusted to agree with the test thermometer. Retest the thermometer after adjustment.
 

TEST 2.
RECORDING THERMOMETERS - TEMPERATURE ACCURACY

Reference: Item 16p (A), (B), (C) and (E)

Application: To all recording and recorder-controller thermometers controllers used to record milk or milk product temperatures during pasteurization or aseptic processing.

Frequency: Upon installation; at least once each three (3) months thereafter; whenever the recording pen-arm setting requires frequent adjustment; when the sensing element has been replaced; or when a regulatory seal has been broken.

Criteria: Within ± 0.5°C (± 1°F), in specified scale range. Provided, that on batch pasteurizers used solely for thirty (30) minute pasteurization of milk or milk products at temperatures above 71°C (160°F), the recording thermometers shall be accurate to within ± 1°C (± 2° F), between 71°C (160° F) and 77°C (170°F).

Apparatus:

  1. The indicating thermometer previously tested against a known accurate thermometer;
  2. Water oil or other suitable media bath and agitator;
  3. Suitable means of heating the media bath; and
  4. Ice.

NOTE: When this Test is performed on recorder-controllers used with HHST pasteurization or aseptic processing systems that operate at or above the boiling point of water, an oil or other suitable media bath shall be substituted for the processing (operating) temperature water mentioned in Procedures 1, 4, 5, 6, and 7 as well as the boiling water mentioned in Procedures 2, 3 and 5. The temperature of the oil bath that is used in place of the boiling water shall be above the normal operating range but below the highest temperature division on the chart.

Method: The testing of a recording thermometer for temperature accuracy involves the determination of whether or not the temperature pen-arm will return to within 0.5°C (1°F), or 1°C (2°F) as provided in the Criteria above, of its previous setting, after exposure to high heat and melting ice.

Procedure:

  1. Adjust the recording pen to read exactly as the previously tested indicating thermometer, in the temperature range for the process being used, after a stabilization period of five (5) minutes, two (2) minutes for electronic recording thermometers, at a constant temperature. The bath shall be rapidly agitated throughout the stabilization period.
  2. Prepare a second media bath by heating to the boiling point, or in the case of HHST or aseptic systems, to a temperature above the normal operating range but below the highest temperature division on the chart, and maintain temperature. Prepare a third container with melting ice. Place all media baths within working distance of the temperature-sensing element(s).
  3. Immerse the recording thermometer sensing element into the boiling water, or in the case of HHST or aseptic processing systems into the media bath described above, for not less than five (5) minutes, two (2) minutes for electronic recording thermometers.
  4. Remove the recording thermometer sensing element from the boiling water or other media bath and immerse it in the media bath at a temperature within the temperature range for the process being used. Allow a five (5) minute, two (2) minutes for electronic recording thermometers, stabilization period for both indicating and recording thermometers. Compare readings of the indicating and recording thermometers. The recording thermometer reading should be within ± 0.5°C (± 1°F) or ± 1°C (± 2°F) as provided above, of the indicating thermometer reading.
  5. Remove the recording thermometer sensing element from the bath in the temperature range for the process being used, and immerse in melting ice for not less than five (5) minutes, two (2) minutes for electronic recording thermometers.
  6. Remove the recording thermometer-sensing element from the ice water and immerse in a bath at a temperature, range for the process being used. Allow a five (5) minute, two (2) minutes for electronic recording thermometers, stabilization period for both indicating and recording thermometers. Compare readings of the indicating and recording thermometers. The recording thermometer reading should be within ± 0.5°C (± 1°F), or ± 1°C (± 2°F) as provided above, of the indicating thermometer reading.
  7. Re-seal the regulatory controls as necessary and record the indicating and recording thermometer readings obtained from Procedures 1, 4, and 6.

Corrective Action: If the recording thermometer pen does not return to ± 0.5°C (± 1°F), or ± 1°C (± 2°F) as provided above, of indicating thermometer reading at Procedures 4 and 6, the recording thermometer shall be repaired or replaced as necessary.
 

TEST 3.
RECORDING THERMOMETERS - TIME ACCURACY

Reference: Item 16p (A), (B), (C) and (E)

Application: To all recording and recorder-controller thermometers used to record the time of pasteurization or aseptic processing, including those used to record flow rates in magnetic flow meter based timing systems.

Frequency: Upon installation; at least once each three (3) months thereafter; or whenever the seal of a programmable recorder-controller has been broken.

Criteria: The recorded time of pasteurization or aseptic processing shall not exceed the true elapsed time.

Apparatus:

  1. A watch, graduated at intervals not to exceed one (1) minute, and accurate to within five (5) minutes in twenty-four (24) hours; and
  2. A pair of dividers or any other suitable device for measuring short distances.

Method: Comparison of the recorded time over a period of not less than thirty (30) minutes with a watch of known accuracy. For recorders utilizing electric clocks, check the cycle on the faceplate of the clock with a known cycle and observe that the clock is in operating condition.

Procedure:

  1. Determine if the chart is appropriate for the recording thermometer. Insure that the recording pen is aligned with the time arc of the chart at both the center and the outside edge.
  2. Inscribe a reference mark at the pen point on the recording chart and record the time.
  3. At the end of thirty (30) minutes by the watch, inscribe a second reference mark at the pen point position on the chart.
  4. Determine the distance between the two (2) reference marks and compare the distance with the time-scale divisions on the recording chart at the same temperature.
  5. For electric clocks, remove the faceplate and compare the cycle specification on the faceplate with the current cycle utilized.
  6. Re-seal the regulatory controls as necessary; enter the findings on the chart and initial and record the results.

Corrective Action: If recorded time is incorrect, the clock should be adjusted or repaired.
 

back to top

TEST 4.
RECORDING THERMOMETERS - CHECK AGAINST INDICATING THERMOMETERS

Reference: Item 16p (A), (B), (C) and (E)

Application: To all recording and recorder-controller thermometers used to record milk or milk product temperatures during pasteurization or aseptic processing.

Frequency: Upon installation and at least once each three (3) months by the Regulatory Agency, or HACCP qualified industry person, acceptable to the Regulatory Agency, qualified under Item 16p(E)2; and daily by the milk plant operator.

Criteria: The recording thermometer and recorder-controller thermometer shall not read higher than the indicating thermometer.

Apparatus: No supplementary materials required.

Method: This test requires only that the reading of the recording thermometer or the recorder-controller thermometer be compared with the indicating thermometer at a time when both are exposed to milk or milk product at a stabilized pasteurization or aseptic processing temperature.

Procedure:

  1. While the indicating and recording temperatures are stabilized at or above the minimum legal pasteurization or aseptic processing temperature, read the indicating thermometer.
  2. Immediately record and identify on the recording thermometer chart, the observed indicating thermometer temperature reading and the time at which this comparison was made. This may be accomplished by inscribing a line intersecting the recorded temperature arc at the pen location or other methods acceptable to the Regulatory Agency.

NOTE: This test shall be performed while the pasteurization operating temperatures are within the accurate range for the specific thermometers and charts used.

Corrective Action: If the recording thermometer or recorder-controller thermometer reads higher than the indicating thermometer, the pen or temperature adjusting mechanism shall be adjusted by the operator.
 

TEST 5.
FDD - PROPER ASSEMBLY AND FUNCTION

Reference: Item 16p (B), (C) and (E)

Application: Test 5 (parts 1 through 9) does not apply to aseptic processing divert systems, valves or other acceptable controls which may be used in place of a FDD. Parts 1 to 4 and 6 to 8 apply to all FDDs used with continuous-flow pasteurizers. Parts 5 and 9 apply only to FDDs used with HTST pasteurizers.

Frequency: Upon installation; at least once each three (3) months thereafter; or when a regulatory seal has been broken.

Criteria: The FDD shall function correctly in operating situations and shall de-energize the timing pump and all other flow-promoting devices capable of causing flow through the FDD, in the event of malfunction or incorrect assembly.
 

5.1 LEAKAGE PAST VALVE SEAT(S)

Apparatus: Suitable tools for the disassembly of the FDD and the sanitary piping.

Method: Observe the valve seat(s) of the FDD for leakage.

Procedure:

  1. With the system operating on water, place the FDD in the diverted-flow position.
  2. For single stem FDDs, disconnect the forward-flow piping and observe the valve seat for leakage. Check the leak escape ports to see if they are open.
  3. For dual stem FDDs, observe the leak-detect line discharge or sight glass for leakage.

Corrective Action: If leakage is noted, the FDD must be dismantled and defective gaskets replaced or other suitable repairs made.
 

5.2 OPERATION OF VALVE STEM(S)

Apparatus: Suitable tools for tightening the packing nut on the stem(s)

Method: Observe the FDD valve stem(s) for ease of movement.

Procedure: When a stem-packing nut is used, tighten it as much as possible. Operate the system at maximum normal operating pressure and place the FDD in forward and diverted-flow several times. Note the freedom of action of the valve stem.

Corrective Action: If the valve action is sluggish, suitable adjustment or repair shall be made. The stem shall move freely in all positions, when the stem-packing nut is fully tightened.
 

5.3 DEVICE ASSEMBLY - SINGLE STEM DEVICE

Apparatus: Sanitary fitting wrench

Method: When the FDD is improperly assembled and in diverted-flow (below cut-out temperature), observe the function of the timing pump and all other flow-promoting devices capable of causing flow through the FDD.

Procedure:

  1. With the system in operation below the cut-in temperature, unscrew by one-half turn, the 13H hex nut that holds the top of the valve to the valve body. This should de-energize the timing pump and all other flow-promoting devices, which are capable of causing flow through the FDD. This test shall be conducted without piping connected to the forward-flow port of the FDD. (This allows movement of the top of the valve when the hex nut is loosened.) Re-tighten the 13H hex nut.
  2. With the system in operation below the cut-in temperature, remove the connecting key, located at the base of the valve stem. The timing pump and all other flow-promoting devices, which are capable of causing flow through the FDD should be de-energized.
  3. Attempt to restart the timing pump and each flow-promoting device capable of causing flow through the FDD. None of these flow-promoting devices should start or operate.

Corrective Action: If any flow-promoting device fails to respond as indicated, immediate checks of the device assembly and wiring are required to locate and correct the cause.
 

5.4 DEVICE ASSEMBLY - DUAL STEM DEVICE

NOTE: The test procedure presented in this Section is typical of tests accepted by FDA for various specific types of FDDs. Testing details, which may vary, are provided in individual FDD operator's manuals that have been reviewed by FDA and are specified by part number in FDA's Coded Memoranda (M-b's). In each of these FDA accepted test methods, if the words "metering pump" or "timing pump" are used they shall be understood to mean "timing pump and all other flow-promoting devices, which are capable of causing flow through the FDD".

Apparatus: None

Method: Observe the function of the timing pump and all other flow-promoting devices, which are capable of causing flow through the FDD when the FDD is improperly assembled.

Procedure:

  1. With the FDD in diverted-flow, caused by temperature, and the FDD properly assembled, move the FDD to the forward-flow position and disconnect the stem from the actuator.
  2. Move the FDD to the diverted-flow position and turn on the timing pump and all other flow- promoting devices, which are capable of causing flow through the FDD. The timing pump and all other flow-promoting devices must be de-energized and must not run. If any pump starts momentarily and then stops, it may indicate the improper wiring of the one (1) second time delay as allowed in 16p(B)2.b.(10). Separators must be effectively valved-out of the system.
  3. Reassemble the FDD by moving it to the forward-flow position and reconnecting the stem to the actuator.
  4. Repeat the procedure for the other actuator.

Corrective Action: If any of the flow-promoting devices fail to respond as indicated, an immediate check of the FDD assembly and wiring is required to locate and correct the cause.
 

5.5 MANUAL DIVERSION
(Booster pump installed in the HTST system)

Apparatus: None

Method: Observe the response of the system to manual diversion.

Procedure:

  1. With the HTST system in operation and the FDD in the forward-flow position, press the manual diversion button. This should:
    1. Cause the FDD to assume the divert position;
    2. De-energize the booster pump; and
    3. The pressure differential between raw and pasteurized milk or milk product in the regenerator should be maintained.
  2. Operate the HTST system in forward-flow and activate the manual divert button until the raw pressure reaches zero (0) psi. Deactivate the manual divert button and observe the raw milk or milk product and pasteurized milk or milk product pressures. The pressure differential between raw and pasteurized milk or milk product in the regenerator should be maintained.
  3. Re-seal the regulatory controls as necessary.

Corrective Action: If the above described actions do not occur, or the necessary pressure differential between raw and pasteurized milk or milk product is not maintained, the assembly and wiring of the HTST system must be immediately reviewed and the indicated deficiencies corrected or proper adjustments made.
 

5.6 RESPONSE TIME

Apparatus:

  1. Water, oil or other suitable media bath;
  2. Suitable means of heating the media bath; and
  3. Stopwatch.

Method: Determine the elapsed time between the instant of the activation of the control mechanism at cut-out temperature on declining temperature and the instant the FDD takes the fully diverted-flow position.

Procedure:

  1. With the water, oil or suitable media bath at a temperature above cut-out temperature, allow the water, oil or other suitable media to cool gradually. The moment the cut-out mechanism is activated, start the watch. The moment the FDD takes the fully-diverted position, stop the watch.
  2. Re-seal the regulatory controls as necessary and record the results.

Corrective Action: If the response time exceeds one (1) second, immediate corrective action must be taken.
 

5.7 TIME DELAY INTERLOCK WITH TIMING PUMP

Application: To all dual stem FDDs with a manual forward-flow switch.

Apparatus: None

Method: Determine that the device does not assume a manually induced forward-flow position, while the timing pump or any other flow-promoting device, which is capable of causing flow through the FDD is operating.

Procedure: With the system operating in forward-flow, move the control switch to the "Inspect" position and observe that the following events automatically occur in sequence:

  1. The FDD immediately moves to the diverted-flow position and the timing pump and all other flow-promoting devices, which are capable of causing flow through the FDD, are de-energized, or in the case of separators, are effectively valved-out of the system.
  2. The FDD remains in the diverted-flow position while the timing pump and all other flow- promoting devices, which are capable of causing flow through the FDD are running down or in the case of a separator, valving out.
  3. The FDD may assume the forward-flow position only after the timing pump stops turning, and all other flow-promoting devices, which are capable of causing flow through the FDD have also stopped, or in the case of separators, have been effectively valved-out of the system.
  4. Repeat the above procedure by moving the control switch to the “Cleaned-in-Place” (CIP) position.
  5. Record the Test results and seal the control enclosure.

Corrective Action: If the above sequence of events do not occur, either a timer adjustment or wiring change is required.
 

5.8 CIP TIME DELAY RELAY

Application: To all continuous-flow pasteurizer systems in which it is desired to run the timing pump and/or other flow-promoting devices during the CIP cycle without the controls required during product processing.

Criteria: When the mode switch on the FDD is moved from “Process” to “CIP”, the FDD shall move immediately to the diverted position. It shall remain in the diverted position for at least ten (10) minutes, with all public health controls required in “Process” mode functioning, before starting its normal cycling in the “CIP” mode. In HTST systems, the booster pump shall be de-energized during the ten (10) minute time delay.

Apparatus: Stopwatch

Method: Determine that the set point on the time delay relay is equal to or greater than ten (10) minutes.

Procedure:

  1. Operate the pasteurizer in forward-flow, with the mode switch on the FDD in the “Process” position, using water above pasteurization temperature. For magnetic flow meter based timing systems, operate the system, at a flow-rate below the Flow-Alarm set point and above the Loss-of-Signal-Alarm set point.

    NOTE: The appropriate temperature elements may be placed in a water or oil bath to simulate the normal pasteurization temperature of the holding tube as an alternative to heating the water in the system above the pasteurization temperature.

  2. Move the mode switch on the FDD to the “CIP” position. The FDD should move immediately to the diverted position. Start the stopwatch when the FDD moves to the diverted position. Check all controls that are required to be in operation when the system is in the “Process” mode and in diverted-flow. For example, in HTST systems, the booster pump must stop running. Separators located between regenerator sections or on the pasteurized side of the system must be effectively valved-out and stuffer pumps for such separators must be de-energized.
  3. Stop the stopwatch when the CIP timer times out. On most systems this is when the FDD moves to the forward position for its initial cycle in the “CIP” mode. At this time the system may be operated without the controls normally required during product processing. For example, the booster pump may start at this time.
  4. Record the results.
  5. Install and seal the enclosure over the time delay relay.

Corrective Action: If the FDD does not remain in the diverted position for at least ten (10) minutes after the mode switch is moved from “Process” to “CIP”, increase the set point on the time delay relay and repeat this test procedure. All public health controls required when the system is in “Process” mode and in diverted-flow must be functional during these ten (10) minutes. If any of the public health controls are not functional during these ten (10) minutes, adjustments or repairs are needed. In HTST systems, if the booster pump runs at any time during the ten (10) minute delay, the booster pump wiring is in need of repair.
 

5.9 LEAK-DETECT VALVE FLUSH - TIME DELAY

Application: The minimum one (1) second delay applies to HTST continuous-flow pasteurizers in which space between the divert and leak-detect valve is not self-draining in the diverted-flow position.

The maximum of five (5) seconds for this delay is not applicable if:

  1. The minimum acceptable holding time in diverted-flow can be achieved without the use of a restriction in the divert line; or
  2. The timing system is magnetic flow meter based.

Criteria: The leak-detect valve will be flushed for at least one (1) second and not more that five (5) seconds after the divert valve moves to the forward-flow position and before the leak-detect valve moves to the forward position.

Apparatus: Stop watch

Method: Observe the movement of the divert and leak-detect valves to the forward-flow position and measure the time interval between the movement of the two (2) valves.

Procedure:

  1. Move the FDD from the diverted-flow position to the forward-flow position either by:
    1. Raising the temperature above the cut-in set point; or
    2. Operating the HTST pasteurizer above the cut-in temperature in manual divert mode and then releasing the manual divert.
  2. When the divert valve begins to move to the forward-flow position, start the watch.
  3. When the detect valve begins to move to the forward-flow position, stop the watch.
  4. Record the elapsed time.
  5. If the elapsed time is at or above one (1) second and at or below five (5) seconds, seal the time delay.

Corrective Action: If the elapsed time is less than one (1) second or greater than five (5) seconds, appropriate changes to the system or system controls must be made.
 

back to top

TEST 6.
LEAK-PROTECTOR VALVE

Reference: Item 16p (A) and (E)

Application: To all batch (vat) pasteurizer outlet valves and to all batch (vat) pasteurizer inlet valves, which are not disconnected and removed during holding, cooling and emptying periods.

Frequency: Upon installation; and at least once each three (3) months thereafter.

Criteria: No leakage of milk or milk product past the valve seat in any closed position.

Apparatus: No supplementary materials required.

Method: By observing when the piping is disconnected from the valve outlet whether or not leakage past the valve seat occurs when pressure is exerted against the upstream face of the valve.

Procedure:

  1. During normal operation, while milk or milk product pressure is exerted against the valve inlet, fully close the valve and disconnect the outlet piping.

    NOTE: Care must be taken to avoid contamination of the valves or the piping.

  2. Observe whether or not any milk or milk product is leaking past the valve seat into the valve outlet.
  3. In the case of plug-type valves, turn the valve to the just-closed position, and examine the leakage into the valve outlet.
  4. Reconnect the outlet piping.
  5. Record the identity of the valve and findings for the office record.

Corrective Action: If leakage past the valve seat should occur in any closed position, the valve plug should be re-ground, gaskets replaced, or any other necessary steps shall be taken to prevent leakage.
 

TEST 7.
INDICATING THERMOMETERS ON PIPELINES - THERMOMETRIC RESPONSE

Reference: Item 16p (B) and (E)

Application: To all continuous-flow pasteurizers, except those in which the FDD is located downstream of the regenerator and/or cooler section.

Frequency: Upon installation; once each three (3) months thereafter; and whenever the seal on a digital thermometer has been broken.

Criteria: Four (4) seconds under specified conditions.

Apparatus:

  1. Stopwatch;
  2. The indicating thermometer previously tested against a known accurate thermometer;
  3. Water bath and agitator; and
  4. Suitable means of heating the water bath.

Method: By measuring the time required for the reading of the thermometer being tested to increase 7°C (12°F) through a specified temperature range. This range must include the pasteurization temperature. The temperature used in the water bath will depend upon the scale range of the thermometer to be tested.

Procedure:

  1. Immerse the indicating thermometer in the water bath, heated to a temperature at least 11°C (19°F) higher than the minimum scale reading on the indicating thermometer. The bath temperature should be 4°C (7°F) higher than the maximum required pasteurization temperature for which the thermometer is used.
  2. Immerse the indicating thermometer in a bucket of cold water for several seconds to cool it.

    NOTE: Continuous agitation of the water baths during the performance of Procedures 3, 4 and 5 is required. The elapsed time between the end of Procedure 1 and the beginning of Procedure 3 should not exceed fifteen (15) seconds, unless a constant temperature bath is used to prevent the hot water bath from cooling significantly.

  3. Insert the indicating thermometer into a hot water bath to the proper bulb immersion depth.
  4. Start the stopwatch when the indicating thermometer reads 11°C (19°F) below the bath temperature.
  5. Stop the stopwatch when the indicating thermometer reads 4°C (7°F) below the bath temperature.
  6. Record the thermometric response time for the office record.

For Example: For a thermometer used at pasteurization temperature set points of 71.7°C (161°F) and 74.4°C (166°F), a water bath at a temperature of 78.3°C (173°F) could be used. 10.6°C (19°F) lower than a 78.3°C (173°F) water bath would be 67.8°C (154°F); 3.9°C (7°F) lower than a 78.3°C (173°F) water bath would be 74.4°C (166°F). Hence, after immersing the thermometer that has been previously cooled, in the 78.3°C (173°F) bath, the stopwatch is started when the thermometer reads 67.8°C (154°F) and stopped when it reads 74.3°C (166°F).

NOTE: The test included the pasteurization temperature set points of 71.7°C (161°F) and 74.4°C (166°F). If the pasteurization temperature set points had been 71.7°C (161°F) and 79.4°C (175°F), it would not have been possible to include both set points within a 6.7°C (12°F) span. With these set points the test would have to be done separately for each set point.

Corrective Action: If the response time exceeds four (4) seconds, the thermometer should be replaced or returned for repair.
 

TEST 8.
RECORDER/CONTROLLER - THERMOMETRIC RESPONSE

Reference: Item 16p.(B and E)

Application: To all continuous-flow pasteurizers, except those in which the FDD is located at the end of the cooler section.

Frequency: Upon installation and at least once each three (3) months thereafter.

Criteria: Five (5) seconds, under specified conditions.

Apparatus:

  1. Stopwatch;
  2. The indicating thermometer previously tested against a known accurate thermometer;
  3. Water bath and agitator; and
  4. Suitable means of heating the water bath.

Method: Measure the time interval between the instant when the recording thermometer reads 7°C (12°F) below the cut-in temperature and the moment of cut-in by the recorder/controller. This measurement is made when the sensing element is immersed in a rapidly agitated water bath maintained at 4°C (7°F) above the cut-in temperature.

Procedure:

  1. Check and, if necessary, adjust the pen-arm setting of the recording thermometer in the proper reference to agree with the indicating thermometer reading at the pasteurization temperature.
  2. Determine the cut-in temperature of the recorder/controller, either while in normal operation or by using a water bath. (Refer to Test 10)
  3. Remove the sensing element and allow it to cool to room temperature.
  4. Heat the water bath to 4°C (7°F) above the cut-in temperature, while vigorously agitating the bath to insure a uniform temperature.
  5. Immerse the recorder/controller bulb in the bath. Continue agitation during Procedures 6 and 7 below.
  6. Start the stopwatch when the recording thermometer reaches a temperature of 7°C (12°F) below the cut-in temperature.
  7. Stop the stopwatch when the recorder/controller cuts in.
  8. Re-seal the regulatory controls as necessary and record the thermometric response time for office record.

Corrective Action: If the response time exceeds five (5) seconds, the recorder/controller should be repaired.
 

back to top

TEST 9.
REGENERATOR PRESSURE CONTROLS

Reference: Item 16p (D) and (E)

9.1 PRESSURE SWITCHES

Used to control the operation of the booster pump.

Application: To all pressure switches controlling the operation of a booster pump on HTST pasteurizer systems employing regenerators.

Frequency: Upon installation; each three (3) months thereafter; after any change in the booster pump or the switch circuit; and/or whenever the pressure switch seal is broken.

Criteria: The booster pump shall not operate unless there is at least a 6.9 kPa (1 pound) pressure differential on the pasteurized milk or milk product side of the regenerator.

Apparatus: Sanitary pressure gauge and pneumatic testing device, for checking and adjusting pressure switch settings.

Sanitary pressure gauge and pneumatic testing device, for checking and adjusting pressure switch settings.
A simple pneumatic testing device may be made from a discarded 50 millimeters (2 inches)-7BX sanitary tee, with two (2) additional 13H nuts, one (1) of which is provided with a 16A cap, drilled and tapped for a 13 millimeters (½ inch) galvanized iron nipple for the air connection. A hose connection is made to a compressed air source in the milk plant by means of a snap-on fitting. The air pressure can be controlled by pressure-reducing valve (range 0-60 psi) followed by a 13 millimeters (½ inch) globe-type bleeder valve connected into the side outlet of a 13 millimeters (½ inch) tee installed between the pressure-reducing valve and the testing device. The pressure switch to be tested is disconnected from the pasteurizer and connected to another of the outlets of the sanitary tee, and the pressure gauge is connected to the third outlet of the sanitary tee. By careful manipulation of the air pressure reducing valve and the air bleeder valve, the air pressure in the testing device may be regulated slowly and precisely. In operating the device, care should be taken to avoid exposing the pressure switch and the sanitary pressure gauge to excessive pressure that may cause damage. This may be done by first closing off the air pressure regulating valve and opening fully the bleeder valve; these may then be manipulated slowly to bring the air pressure in the testing device within the desired range. A test light of proper voltage should be placed in-series with the pressure switch contact and in parallel with the electrical load, booster pump starter, so the actuation point may be readily determined.

Method: Check and make the adjustment of pressure switch to prevent the operation of the booster pump, unless the pressure of the pasteurized milk or milk product side of the regenerator is greater by at least 6.9 kPa (1 psi) than any pressure that may be generated on the raw side.

Procedure:

  1. Determine the maximum pressure of the booster pump.
    1. Install the sanitary pressure gauge in a tee at the discharge of the booster pump;
    2. Operate the pasteurizer with water; with the FDD in forward-flow; the timing pump operating at the minimum speed possible; and the booster pump operating at its rated speed. If vacuum equipment is located between the raw outlet from the regenerator and the timing pump, it should be bypassed while this determination is made.
    3. Note the maximum pressure indicated by the pressure gauge under these conditions.
  2. Check and set the pressure switch.
    1. Install a sanitary pressure gauge of known accuracy on the pneumatic testing device to which the pressure switch sensing-element should also be connected.
    2. Remove the seal and cover to expose the adjustment mechanism on the pressure switch.
    3. Operate the testing device and determine the pressure gauge reading at the cut-in point of the pressure switch which will light the test lamp. If the switch is short circuited, the lamp will be lighted before air pressure is applied.
    4. The cut-in point should be adjusted, if necessary, so as to occur at a pressure gauge reading at least 6.9 kPa (1 psi) greater than the maximum booster pump operating pressure, as determined under Section 1 of this procedure. Where adjustment is necessary, refer to the manufacturer's instructions for the adjusting procedures. After adjustment, recheck the actuation point and readjust if necessary.
    5. Replace the cover, seal the pressure switch and restore the sensing element to its original location.
    6. Record the maximum booster pump pressure developed and the pressure switch setting for the office record.
       

9.2 DIFFERENTIAL PRESSURE CONTROLLER

Application: Test 9.2.1 applies to all differential pressure controllers used to control the operation of booster pumps on HTST systems or used to control the operation of FDDs on HHST and HTST Pasteurization systems with the FDD located downstream of the pasteurized regenerator and/or final cooler and aseptic processing systems.
Test 9.2.2 applies only to HTST systems with the FDD located immediately following the holding tube.

Test 9.2.3 applies to the testing of continuous flow pasteurization systems in which the differential pressure controller is used to control the operation of the FDD. Test 9.2.3 also applies to aseptic processing systems in which the differential pressure controller is used to control the FDD, milk or milk product divert system, milk or milk product divert valve or other acceptable control system.

Frequency: Upon installation; each three (3) months thereafter; and whenever the differential pressure controller is adjusted or repaired.

Criteria: The booster pump shall not operate, or the pasteurizer shall not operate in forward- flow, unless the milk or milk product pressure in the pasteurized side of the regenerator is at least 6.9 kPa (1 psi) greater than the milk or milk product pressure in the raw side of the regenerator. When the differential pressure controller is used to control the FDD on HHST or aseptic processing systems, and improper pressure occurs in the regenerator, the FDD shall move to the diverted-flow position and remain in diverted-flow until the proper pressures are re-established in the regenerator and all milk or milk product-contact surfaces between the holding tube and FDD have been held at or above the required pasteurization or aseptic processing temperature, continuously and simultaneously for at least the required time.

Apparatus: A sanitary pressure gauge and a pneumatic testing device, described in PRESSURE SWITCHES can be used for checking and adjusting the differential pressure switch setting. (Refer to Test 9.1)

Method: The differential pressure switch is checked and adjusted to prevent the operation of the booster pump, or prevent forward-flow, unless the milk or milk product pressure in the pasteurized, or aseptic, side of the regenerator is at least 6.9 kPa (1 psi) greater than the pressure in the raw side of the regenerator.
 

9.2.1 CALIBRATION OF THE DIFFERENTIAL PRESSURE CONTROLLER PROBES

Procedure:

  1. Loosen the process connection at both pressure sensors and wait for any liquid to drain through the loose connections. Both pointers, or digital displays, should be within 3.5 kPa (0.5 psi) of 0 kPa (0 psi). If not, adjust the pointer(s), or the digital display(s), to read 0 kPa (0 psi).
  2. Remove both sensors from the processor and mount them in a tee, either at the discharge of the booster pump, or connected to the pneumatic testing device. Note the separation between the two (2) pointers or digital displays. The change in elevations of the sensors will have caused some change in the zero readings. Turn on the booster pump switch and depress the test push button to operate the booster pump. If the pneumatic testing device is used in lieu of the booster pump, adjust the air pressure to the normal operating pressure of the booster pump. Note that the pointer, or digital display reading separation is within 6.9 kPa (1 psi) of that observed before the pressure was applied. If not, the instrument requires adjustment or repair.
     
9.2.2 HTST - INTERWIRING OF THE PRESSURE DIFFERENTIAL CONTROLLER WITH THE BOOSTER PUMP

Method: Determine if the booster pump stops when the pressure differential is not properly maintained in the regenerator.

Procedure:

  1. Connect the pasteurized pressure sensor to a testing tee with the other end of the tee capped.

    NOTE: If there is water in the HTST system, ensure that the recorder/controller probe and the pasteurized sensor ports are capped before the timing pump is turned on.

  2. Turn on the timing pump and the booster pump.
  3. Place the recorder/controller probe in hot water, which is above the cut-in temperature.
  4. Turn up the air supply on the tee to provide an adequate pressure differential to start the booster pump.
  5. Decrease the air supply to the testing tee until the pressure is less than 14 kPa (2 psi) of the pressure on the raw milk or milk product pressure sensor. The booster pump should have stopped. Ensure that the FDD remains in the forward-flow position and the timing pump continues to operate.
  6. Reseal the regulatory controls as necessary and record the Test results for the office record.

Corrective Action: If the booster pump fails to stop when the pressure differential is not maintained, have the milk plant maintenance personnel determine and correct the cause.
 

9.2.3 INTERWIRING OF THE PRESSURE DIFFERENTIAL CONTROLLER WITH THE FDD IN AN HHST CONTINUOUS FLOW PASTEURIZATION SYSTEM; OR AN ACCEPTABLE ALTERNATIVE DEVICE, OR SYSTEM IN ASEPTIC PROCESSING EQUIPMENT

Application:

  1. To all differential pressure controllers used to control the operation of FDDs on continuous flow pasteurization systems with the FDD located downstream of the regenerator and/or final cooler, and
  2. To all differential pressure controllers used to control the operation of FDDs, milk or milk product divert systems, milk or milk product divert valve(s) or other acceptable control systems used in aseptic processing equipment.

Apparatus: A sanitary pressure gauge and a pneumatic testing device, described in PRESSURE SWITCHES can be used for checking and adjusting the differential pressure switch setting. (Refer to Test 9.1)

Method: The differential pressure switch is checked and adjusted to prevent forward-flow, unless the milk or milk product pressure in the pasteurized side of the regenerator is at least 6.9 kPa (1 psi) greater than the pressure in the raw milk or milk product side of the regenerator. In the case of milk or milk product-to-water-to-milk or milk product regenerators, protected on the pasteurized or aseptic side, the "water side" of the regenerator shall be considered to be the "raw product side" for purposes of this Test.

Procedure:

  1. Wire the test lamp in series with the signal from the pressure differential switch to the FDD.
  2. Calibrate the pressure switch and probes. (Use Test 9.2.1.)
  3. Adjust the pressure on the pressure switch sensors to their normal operating pressures, with the pasteurized or aseptic pressure at least 14 kPa (2 psi) higher than the raw product pressure.
    1. The test lamp should be lit. If not, increase the pasteurized or aseptic pressure, or lower the raw product pressure, until the test light is lit.
    2. Gradually lower the pasteurized or aseptic side, or raise the raw product pressure until the test light turns off.
    3. The test light should turn off when the pasteurized or aseptic pressure is at least 14 kPa (2 psi) higher than the raw product pressure.
    4. Note the differential pressure at the point the light turns off.
    5. Gradually raise the pasteurized or aseptic pressure, or lower the raw product pressure, until the test light turns on.
    6. The test light should not turn on until the pasteurized or aseptic pressure is at least 14 kPa (2 psi) higher than the raw product pressure. Note the differential pressure at the point the light turns off.

      NOTE: This test may be completed using a pneumatic testing device capable of producing differential pressures on the probes. This device should be capable of being operated, and be operated, in a manner so as to duplicate the conditions described above.
      4. Seal the instrument and record the Test results for the office record.

  4. Seal the instrument and record the Test results for the office record.
     

9.3 ADDITIONAL HTST TESTS FOR BOOSTER PUMPS - INTERWIRING

Application: To all booster pumps used for HTST systems where the FDD is located immediately after the holding tube.

Criteria: The booster pump shall be wired so it cannot operate if the FDD is in the diverted position or if the timing pump is not in operation.

Apparatus:

  1. A sanitary pressure gauge and pneumatic testing device as described in Test 9.1 Pressure Switches;
  2. Water bath and agitator; and
  3. Suitable means of heating the water bath.
     
9.3.1 BOOSTER PUMPS - INTERWIRED WITH FDD

Method: Determine if the booster pump stops by dropping the temperature and causing the FDD to divert.

Procedure:

  1. Connect the pasteurized pressure sensor to a testing tee with the other end of the tee capped.

    NOTE: If there is water in the HTST system, ensure that the recorder/controller probe and the pasteurized sensor ports are capped before the timing pump is turned on.

  2. Turn on the timing pump and the booster pump.
  3. Place the recorder/controller probe in hot water, which is above the cut-in temperature.
  4. Turn up the air supply on the tee to provide an adequate pressure differential to start the booster pump.
  5. Remove the recorder/controller probe from the hot water.
  6. When the FDD moves to the diverted-flow position, the booster pump must stop. Ensure that the pressure differential remains adequate and the timing pump continues to operate.
  7. Reseal the regulatory controls as necessary and record the Test results for the office records.

Corrective Action: If the booster pump fails to stop when the FDD is in the diverted-flow position, have the milk plant maintenance personnel check the wiring and correct the cause.
 

9.3.2 BOOSTER PUMPS - INTERWIRED WITH THE TIMING PUMP

Method: Determine if the booster pump stops when the timing pump is off.

Procedure:

  1. Connect the pasteurized pressure sensor to a testing tee with the other end of the tee capped.

    NOTE: If there is water in the HTST system, ensure that the recorder/controller probe and the pasteurized sensor ports are capped before the timing pump is turned on.

  2. Turn on the timing pump and the booster pump.
  3. Place the recorder/controller probe in hot water, which is above the cut-in temperature.
  4. Turn up the air supply on the tee to provide an adequate pressure differential to start the booster pump. The booster pump should start running.
  5. Turn off the timing pump. The booster pump must stop. Ensure that the pressure differential remains adequate and the FDD remains in the forward-flow position.
  6. Reseal the regulatory controls as necessary and record the Test results for the office record.

Corrective Action: If the booster pump fails to stop when the timing pump has been turned off, have the milk plant maintenance personnel determine and correct the cause.
 

back to top

TEST 10.
MILK OR MILK PRODUCT-FLOW CONTROLS AND MILK OR MILK PRODUCT TEMPERATURE AT CUT-IN AND CUT-OUT

References: Item 16p (B), (C) and E)

Milk or milk product-flow controls shall be tested for milk or milk product temperature at cut-in and cut-out by one (1) of the following applicable tests at the frequency prescribed:
 

10.1 HTST PASTEURIZERS

Application: All recorder/controllers used in connection with HTST pasteurizers, except those in which the FDD is located at the end of the cooler section.

Frequency: Upon installation; at least once each three (3) months thereafter by the Regulatory Agency, or HACCP qualified industry person, acceptable to the Regulatory Agency, qualified under Item 16p(E)2; daily by the milk plant operator; or when a regulatory seal has been broken.

Criteria: No forward-flow until the pasteurization temperature has been reached. Flow diverted before the temperature drops below the minimum pasteurization temperature.

Apparatus: No supplemental materials needed.

Method: By observing the actual temperature of the indicating thermometer at the instant forward-flow starts (cut-in) and stops (cut-out).

Procedure:

  1. Cut-in temperature:
    1. While milk, milk product or water is completely flooding the sensing element of the recorder/controller and the indicating thermometer, increase the heat gradually so as to raise the temperature of the milk, milk product or water at a rate not exceeding 0.5°C (1°F) every thirty (30) seconds. If a water bath is used in place of milk, milk product or water flowing through the system, the water bath shall be adequately agitated during this Test.
    2. Observe the indicating thermometer reading at the moment forward-flow starts, i.e., the FDD moves. Observe that the frequency pen reading is synchronized with the recording pen on the same reference arc.
    3. Record the indicating thermometer reading on the recording thermometer chart and initial. The Regulatory Agency shall record Test findings.
  2. Cut-out temperature:
    1. After the cut-in temperature has been determined, and while the milk, milk product or water is above the cut-in temperature, allow the milk, milk product or water to cool slowly at a rate not exceeding 0.5°C (1°F) per thirty (30) seconds. Observe the indicating thermometer reading at the instant forward-flow stops.
    2. Re-seal the regulatory controls as necessary and record the indicating thermometer reading on the recording thermometer chart and initial.

Corrective Action: Should the reading be below the minimum pasteurization temperature, the cut-in and cut-out mechanism and/or the differential temperature mechanism should be adjusted to obtain proper cut-in and cut-out temperatures by repeated tests. When compliance is achieved, seal the recorder/controller mechanism.
 

10.2 PASTEURIZERS AND ASEPTIC PROCESSING SYSTEMS USING INDIRECT HEATING

Application: All HHST and HTST pasteurizers with the FDD located downstream of the regenerator and/or final cooler and aseptic processing systems using indirect heating. When testing aseptic processing systems, the "milk or milk product divert system", or “milk or milk product divert valve" or "acceptable control system" may be substituted for the “FDD" when it is referenced in this Test.

Frequency: Upon installation; every three (3) months thereafter; and whenever the thermal controller seal is broken.

Criteria: The pasteurizer or aseptic processor shall not operate in forward-flow unless the pasteurization or aseptic processing temperature has been achieved. The milk or milk product flow shall be diverted at a temperature lower than the chosen pasteurization or aseptic processing standard.

Apparatus: No supplemental materials needed.

Method: The cut-in and cut-out temperatures are determined by observing the actual temperature in the constant temperature bath at which the two (2) sensing elements signal forward-flow (cut-in) and diverted-flow (cut-out).

Procedure:

  1. Wire the test lamp in series with the control contacts of the holding tube sensing element. Immerse this sensing element in the constant temperature bath. Raise the bath temperature at a rate not exceeding 0.5°C (1°F) every thirty (30) seconds. Observe the temperature reading at the cut-in temperature. Record the temperature for the office record.
  2. After the cut-in temperature has been determined and while the bath is above the cut-in temperature, allow the bath to cool slowly at a rate not exceeding 0.5°C (1°F) per thirty (30) seconds. Observe the temperature reading on the thermal-limit-controller when the test lamp goes out, cut-out temperature. Determine that the cut-out temperature, on the thermal-limit-controller is equivalent to or greater than the chosen pasteurization or aseptic processing standard. Where adjustment is necessary, refer to the manufacturer's instructions. After adjustment, repeat the procedure above, and when the results are satisfactory, record the results for the office records.
  3. Repeat the procedure for the FDD sensing element. When proper cut-out temperature has been verified for both sensing elements, seal the thermal-limit-controller system.
     

10.3 HHST PASTEURIZERS AND ASEPTIC PROCESSING SYSTEMS USING DIRECT HEATING

Application: All HHST and HTST pasteurizers with the FDD located downstream of the regenerator and/or final cooler and aseptic processing systems using direct heating. When testing aseptic processing systems, the "milk or milk product divert system" or "milk or milk product divert valve" or "acceptable control system" may be substituted for the "FDD" when it is referenced in this Test.

Frequency: Upon installation; every three (3) months thereafter; and whenever the thermal-limit-controller seal is broken.

Criteria: The pasteurizer or aseptic processor shall not operate in forward-flow unless the pasteurization or aseptic processing temperature has been achieved. The milk or milk product flow shall be diverted at a temperature lower than the chosen pasteurization or aseptic processing standard.

Apparatus: No supplemental materials needed.

Method: The cut-in and cut-out temperatures are determined by observing the actual temperature in the constant temperature bath at which each of the three (3) sensing elements signals forward-flow (cut-in) and diverted-flow (cut-out).

Procedure:

  1. Wire the test lamp in series with the control contacts of the holding tube sensing element. Immerse this sensing element in the constant temperature bath. Raise the bath temperature at a rate not exceeding 0.5°C (1°F) every thirty (30) seconds. Observe the temperature reading on the thermal-limit-controller when the test lamp lights, cut-in temperature. Record the temperature for the office record.
  2. After the cut-in temperature has been determined and while the bath is above the cut-in temperature, allow the bath to cool slowly at a rate not exceeding 0.5°C (1°F) per thirty (30) seconds. Observe the temperature reading on the thermal-limit-controller when the test lamp goes out, cut-out temperature. Determine that the cut-out temperature, on the thermal-limit- controller, is equivalent to or greater than the chose pasteurization or aseptic processing standard. Where adjustment is necessary, refer to the manufacturer's instructions. After adjustment, repeat the procedure above and when the results are satisfactory, record the results for the office record.
  3. Repeat the procedure for the other two (2) sensing elements, i.e., the vacuum chamber and the FDD. Rewire the test lamp in series with the control contacts from each sensing element, respectively. When proper cut-out temperatures have been verified for all three (3) sensing elements, seal the thermal-limit-controller system.
     

back to top

TEST 11.
CONTINUOUS-FLOW HOLDING TUBES - HOLDING TIME

Reference: Item 16p (B), (C) and (E)

Continuous-flow holding tubes shall be tested for holding times by one (1) of the following applicable tests:
 

11.1 HTST PASTEURIZERS
(Except for magnetic flow meter based timing systems)

Application: To all HTST pasteurizers employing a holding time of fifteen (15) seconds or longer.

Frequency: Upon installation; semi-annually thereafter; whenever the seal on the speed setting is broken; any alteration is made affecting the holding time, the velocity of the flow, such as the replacement of the pump, motor, belt, drive or driven pulleys, or a decrease in the number of HTST plates or the capacity of holding tube; or whenever a check of the capacity of the holding tube indicates a speedup.

Criteria: Every particle of milk or milk product shall be held for at least fifteen (15) seconds in both the forward and diverted-flow positions.

Apparatus:

  1. Electrical conductivity measuring device, which is capable of detecting change in conductivity and equipped with standard electrodes;
  2. Table salt (sodium chloride);
  3. A suitable apparatus for injecting the salt solution (50 ml syringe); and
  4. An accurate timing device.

Method: The holding time is determined by timing the interval for an added trace substance to pass through the holding tube. Although the time interval of the fastest particle of milk is desired, the conductivity test is made with water. The results found with water are converted to the milk flow time, by formulation, since a pump may not deliver the same amount of milk as it does water.

Procedure:

  1. Examine the entire system to insure that all flow-promoting equipment is operating at maximum capacity and all flow-impeding equipment is so adjusted or bypassed as to provide the minimum of resistance to the flow. There shall be no leakage on the suction side of the timing pump.
  2. Adjust the variable speed pump to its maximum capacity, preferably with a new belt and full size impellers. Check the homogenizer for seals, and/or gears or pulley identification. Check the AC variable speed timing pump control box for seals. For systems that employ a liquid ingredient injection (slurry) system as described in Appendix H., the slurry pump must be energized and running at its maximum speed and the slurry supply tank must be completely filled with water.
  3. Install one (1) electrode at the inlet to the holding tube and the other electrode in the holding tube outlet.
  4. Operate the pasteurizer, using water at pasteurization temperature, with the FDD in the forward-flow position.
  5. Quickly inject saturated sodium chloride solution into the holding tube inlet.
  6. The timer should start when it detects a change in conductivity and the beginning of the holding tube.
  7. The timer should stop when it detects a change in conductivity and the end of the holding tube.
  8. Record the results.
  9. Repeat the test six (6) or more times, until six successive results are within 0.5 seconds of each other. The average of these six (6) tests is the holding time for water in forward-flow. When consistent readings cannot be obtained, purge the equipment, check instruments and connections and check for air leakage on the suction side. Repeat this Test. Should consistent readings not be obtained, use the fastest time as the holding time for water.
  10. Repeat Procedures 4 through 9 for the holding time on water in diverted-flow. For all gear driven timing pumps; or for those homogenizers used as timing pumps, when the measured holding time for water is less than 120% of the legal holding time, complete Procedures 11, 12 and 13. For those homogenizers used as timing pumps, when the measured holding time for water is 120% or more of the legal holding time, Procedure 11 is optional and 12 and 13 are not required.
  11. With the pump at the same speed and all other equipment adjusted as in Procedure 1, time the filling of a 38 liter (10 gallon) can with a measured weight of water, using the discharge outlet with the same head pressure as in normal operation. Average the time of several trials. Since flow rates of the large capacity units make it very difficult to check by filling a 38 liter (10 gallon) can, it is suggested, that a calibrated tank of considerable size be used.
  12. Repeat Procedure 11 using milk.
  13. Compute the holding time for milk from one (1) of the following formulas, either by volume or by weight. Compute separately for forward-flow and diverted-flow. Re-seal the regulatory controls as necessary.

    BY VOLUME:

    The holding time for milk is equal to the holding time for water; times the quotient of the time it takes to deliver a volume of milk; divided by the time it takes to deliver the same volume of water.

    Tm = Tw (Vm / Vw)

    Where:

    Tm = Adjusted product holding time for milk.

    Tw = Holding time for water, the salt test results.

    Vw = Time, usually in seconds, that it takes to pump a volume of water.

    Vm = Time, usually in seconds, that it takes to pump the same volume of milk.

    BY WEIGHT (Using specific gravity):

    The holding time for milk is equal to the specific gravity of milk; times the holding time for water; times the quotient of the time it takes to deliver a measured weight of milk; divided by the time it takes to deliver the same weight of water.

    Tm = 1.032 x Tw (Wm / Ww)

    Where:

    1.032 = The specific gravity of milk.

    Tm = Adjusted product holding time for milk.

    Tw = Holding time for water, the salt test results.

    Wm = Time, usually in seconds, that it takes to pump a measured weight of milk.

    Ww = Time, usually in seconds, that it takes to pump the same measured weight of water.

  14. Record the results for the office record.

Corrective Action: When the computed holding time for milk is less than that required, either in forward-flow or diverted-flow, the speed of the timing pump shall be reduced or an adjustment made in the holding tube and the timing test repeated until a satisfactory holding time is achieved. Should an orifice be used to correct the holding time in diverted-flow, there should be no excessive pressure exerted on the underside of the valve seat of the FDD. Governors shall be sealed on motors that do not provide a constant speed as provided in Item 16p(B)5.b.
 

11.2A MAGNETIC FLOW METER BASED TIMING SYSTEMS CONTINUOUS FLOW - HOLDING TIME

Application: To all HTST pasteurizers with a magnetic flow meter based timing system, used in lieu of a timing pump.

Frequency: Upon installation; semiannually thereafter; whenever a seal on the flow alarm is broken; any alteration is made affecting the holding time, the velocity of the flow or the capacity of holding tube; or whenever a check of the capacity indicates a speed up.

Criteria: Every particle of milk or milk product shall be held for at least a minimum holding time in both the forward and diverted-flow positions.

Apparatus:

  1. Electrical conductivity measuring device, which is capable of detecting change in conductivity and equipped with standard electrodes;
  2. Table salt (sodium chloride);
  3. A suitable apparatus for injecting the salt solution (50 ml syringe);
  4. An accurate timing device.

Method: The holding time is determined by timing the interval for an added trace substance to pass through the holding tube.

Procedure:

  1. Examine the entire system to ensure that all flow-promoting equipment is operating at maximum capacity and all flow-impeding equipment is so adjusted or bypassed as to provide the minimum resistance to the flow.
  2. Adjust the set point on the flow alarm to its highest possible setting.
  3. Adjust the set point on the flow recorder/controller to a flow rate estimated to yield an acceptable holding time.
  4. Install one (1) electrode at the inlet to the holding tube and the other electrode at the holding tube outlet.
  5. Operate the pasteurizer, using water, above the pasteurization temperature, with the FDD in forward-flow.
  6. Quickly inject the saturated sodium chloride solution into the holding tube inlet.
  7. The timer should start when it detects a change in conductivity and the beginning of the holding tube.
  8. The timer should stop when it detects a change in conductivity and the end of the holding tube.
  9. Record the results.
  10. Repeat the test six (6) or more times, until six (6) successive results are within 0.5 seconds of each other. The average of these six (6) tests is the holding time for water in forward-flow. When consistent readings cannot be obtained, purge the equipment, check the instruments and connections; and check for air leakage on the suction side of the pump, located at the constant-level tank. Repeat this Test. If six (6) consecutive readings cannot be achieved within 0.5 seconds of each other, the pasteurizing system is in need of repair.
  11. With the flow recorder/controller at the same set point as in Procedure 3, time the filling of a 38 liter (10 gallon) can with a measured volume of water using the discharge outlet, with the same head pressure as in normal operation. Average the time of several trials. Since the flow rates of the large capacity units make it very difficult to check by filling a 38 liter (10 gallon) can, it is suggested that a calibrated tank of considerable size be used. This procedure is not a required Test; it is at the option of the Regulatory Agency.
  12. Re-seal the regulatory controls as necessary and record this result for the office record.

Corrective Action: When the computed holding time for milk is less than that required, the set point on the flow recorder/controller shall be decreased, or an adjustment made in the holding tube, and the timing test repeated until a satisfactory holding time is achieved.
 

back to top

11.2B CONTINUOUS-FLOW HOLDING TUBES - FLOW ALARM

Application: To all continuous-flow pasteurization and aseptic processing systems using a magnetic flow meter based timing system to replace a timing pump. When testing aseptic processing systems, the "milk or milk product divert system" or "milk or milk product divert valve" or "acceptable control system" may be substituted for the "FDD" when it is referenced in this Test.

Frequency: Upon installation; semiannually thereafter; whenever the seal on the flow alarm is broken; any alteration is made affecting the holding time, the velocity of the flow or the capacity of holding tube; or whenever a check of the capacity indicates a speedup.

Criteria: When flow rate equals or exceeds the value at which the holding time was measured, the flow alarm shall cause the FDD to assume the diverted position, even though the temperature of the milk or milk product in the holding tube is above the pasteurization or aseptic processing temperature.

Apparatus: None

Method: Adjust the set point of the flow alarm so that flow is diverted when the flow rate equals or exceeds the value at which the holding time was measured or calculated. (Refer to Procedure 3 or 4 of this Test)

Procedure:

  1. Operate the pasteurizer or aseptic processing equipment in forward-flow, at the flow rate at which holding time was measured, using water above the pasteurization or aseptic processing temperature.

    NOTE: The appropriate temperature elements may be placed in a water or oil bath to simulate the normal pasteurization or aseptic processing temperature of the holding tube as an alternative to heating the water in the system above the pasteurization or aseptic processing temperature. Observation and recording of this temperature should be done as described in Procedures 3 and 4 below.

  2. Adjust the set point on the flow alarm slowly downward until the frequency pen on the flow recorder/controller indicates that flow has been diverted.

    NOTE: When performing this Test on systems that operate above the boiling point of water, be sure that the system is cooling to avoid the possibility of serious burns.

  3. Observe that the FDD moved to the diverted position, while water passing through the holding tube remained above the pasteurization or aseptic processing temperature.
  4. Re-seal the regulatory controls as necessary and record the set point of the flow alarm; the occurrence of flow-diversion; and the temperature of the water in the holding tube, for the office record.

Corrective Action: If the FDD does not move to the diverted position, when the frequency pen of the recorder/controller indicates a diversion, a modification or repair of the control wiring is required.
 

11.2C CONTINUOUS-FLOW HOLDING TUBES - LOW FLOW/LOSS-OF-SIGNAL ALARM

Application: To all continuous-flow pasteurization and aseptic processing systems using a magnetic flow meter based timing system to replace a timing pump. When testing aseptic processing systems, the "milk or milk product divert system" or "milk or milk product divert valve" or "acceptable control system" may be substituted for the "FDD" when it is referenced in this Test.

Frequency: Upon installation; semiannually thereafter; whenever the seal on the flow alarm is broken; or any alteration is made affecting the holding time.

Criteria: Forward-flow occurs only when flow rates are above the loss-of-signal alarm set point.

Apparatus: None

Method: By observing the actions of the frequency pens on the recorder/controller and the position of the FDD.

Procedure:

  1. Operate the pasteurizer or aseptic processing equipment in forward-flow, at a flow rate below the flow alarm set point and above the low flow/loss-of-signal alarm set point, using water.
  2. Disrupt power to the magnetic flow meter or decrease the flow through the flow meter below the low flow/loss-of-signal alarm set point. Observe that the FDD and both the safety thermal limit recorder/controller frequency pen and the flow rate frequency pen assume the diverted-flow position.
  3. Re-seal the regulatory controls as necessary and record the results for the office record.

Corrective Action: If the valve does not divert or the pens do not move, adjustment of the low flow/loss-of-signal alarm or a modification or repair of the control wiring is required.
 

11.2D CONTINUOUS-FLOW HOLDING TUBES - FLOW CUT-IN AND CUT-OUT

Application: To all HTST pasteurizers using a magnetic flow meter based timing system to replace a timing pump.

Frequency: Upon installation; semiannually thereafter; whenever the seal on the flow alarm is broken; any alteration is made affecting the holding time, the velocity of the flow or the capacity of holding tube; or whenever a check of the capacity indicates a speedup.

Criteria: Forward-flow occurs only when flow rates are below the flow alarm set point and above the low flow/loss-of-signal alarm set point.

Apparatus: None

Method: By observing the recorder/controller readings along with the action of the frequency pen on the recorder/controller.

Procedure:

  1. Operate the pasteurizer in forward-flow, at a flow rate below the flow alarm set point and above the low flow/loss-of-signal alarm set point, using water above the pasteurization temperature.
  2. Using the flow recorder/controller, increase the flow rate slowly until the frequency pen on the recorder/controller indicates a flow diversion, flow cut-out point. The FDD will also assume the diverted position. Observe the reading of flow rate from the recorder/controller at the instant flow cut-out occurs, as indicated by the frequency pen.
  3. With the pasteurizer operating on water, above the pasteurization temperature, and with the FDD diverted because of excessive flow rate, slowly decrease the flow rate until the frequency pen on the flow recorder/controller indicates the start of a forward-flow movement, flow cut-in point. Because of the time delay relay described in Test 11.2, the FDD will not move immediately to the forward-flow position. Observe the reading from the recorder/controller at the instant flow cut-in occurs, as indicated by the frequency pen.
  4. Re-seal the regulatory controls as necessary and record the results for the office record.

Corrective Action: If the cut-in or cut-out point occurs at a flow rate equal to or greater than the value at which holding time was measured, adjust the flow alarm to a lower set point and repeat the Test.
 

back to top

11.2E CONTINUOUS-FLOW HOLDING TUBES - TIME DELAY RELAY

Application: To all HTST pasteurizers using a magnetic flow meter based timing system to replace a timing pump.

Frequency: Upon installation; semiannually thereafter; whenever the seal on the flow alarm is broken; any alteration is made affecting the holding time, the velocity of the flow or the capacity of the holding tube; or whenever a check of the capacity indicates a speedup.

Criteria: Following the flow cut-in, as described in Test 11.2D, forward-flow shall not occur until all milk or milk product in the holding tube has been held at or above pasteurization temperature for at least the minimum holding time.

Apparatus: Stopwatch

Method: Set the time delay equal to or greater than the minimum holding time.

Procedure:

  1. Operate the pasteurizer in forward-flow, at a flow rate below the flow alarm set point and above the low flow/loss-of-signal alarm set point, using water above the pasteurization temperature.
  2. Using the flow recorder/controller, increase the flow rate slowly until the frequency pen on the flow recorder/controller indicates a diversion movement and the FDD moves to the diverted position. There shall be no time delay between the movements of the frequency pen and the FDD.
  3. With the pasteurizer operating on water, above the pasteurization temperature, with the FDD diverted because of excessive flow rate, slowly decrease the flow rate.
  4. Start the stopwatch the instant the frequency pen on the flow recorder/controller indicates the start of a forward-flow movement.
  5. Stop the stopwatch the instant the FDD starts to move to the forward-flow position.
  6. Record the results for the office record.
  7. Install and seal the enclosure over the time delay relay.

Corrective Action: If the time delay is less than the minimum holding time, increase the time setting on the time delay and repeat Test 11.2E.
 

11.2F HIGH FLOW ALARM RESPONSE TIME

Application: To all continuous-flow pasteurization and aseptic processing systems using a magnetic flow meter based timing system to replace a timing pump. When testing aseptic processing systems, the "milk or milk product divert system" or "milk or milk product divert valve" or "acceptable control system" may be substituted for the "FDD" when it is referenced in this Test. Frequency: Upon installation; semiannually thereafter; whenever the seal on the flow alarm is broken; any alteration is made affecting the holding time, the velocity of the flow or the capacity of the holding tube; or whenever a check of the capacity indicates a speedup. Criteria: When flow rate equals or exceeds the value at which the holding time was measured, the flow alarm shall cause the FDD to assume the diverted position within one (1) second.

Apparatus: Stopwatch.

Method: Rapidly increase the flow rate to exceed the high flow alarm and verify that the FDD shifts to the diverted position within one (1) second.

Procedure:

  1. Operate the pasteurizer or aseptic processing equipment in forward-flow, at a flow rate 25% below the high flow alarm as determined in Test 11.2B (Procedure 2).
  2. Mark the recorder chart with the high flow alarm set point.

    NOTE: The appropriate temperature elements may be placed in a water or oil bath to simulate the normal pasteurization or aseptic processing temperature of the holding tube as an alternative to heating the water in the system above the pasteurization or aseptic processing temperature. Observation and recording of this temperature should be done as described in Procedures 3 and 4 below.

  3. Increase the system flow rate as rapidly as practical to a point above the high flow alarm set point.

    NOTE: When performing this Test on systems that operate above the boiling point of water, be sure that the system is cooling to avoid the possibility of serious burns.

  4. Start the stopwatch when the flow rate recorder pen exceeds the high flow alarm set point.
  5. Stop the stopwatch when the FDD has moved to the diverted position.
  6. Record the elapsed time for the office record.

Corrective Action: If the response time exceeds one (1) second, immediate corrective action must be taken.
 

11.3 CALCULATED HOLD FOR INDIRECT HEATING

Application: To all HHST pasteurizers using indirect heating.

Frequency: When installed; semiannually thereafter; whenever the seal on the speed setting is broken; whenever any alteration is made affecting the holding time, the velocity of the flow, i.e., replacement of the pump, motor, belt, driver or driven pulley, decrease in number of heat-exchange plates or the capacity of holding tube; and whenever a check of the capacity indicates a speedup.

Criteria: Every particle of milk or milk product shall be held for the minimum holding time in both the forward and diverted-flow positions.

Apparatus: No supplemental materials needed.

Method: Fully developed laminar flow is assumed and holding tube length is calculated. An experimental determination of the pumping rate is required; this is accomplished by determining the time required for the pasteurizer to fill a vessel of known volume; converting these data by division to obtain flow rate in gallons per second; and multiplying this value by the proper value in Table 14 to determine the required holding tube length. Holding tube lengths for HHST pasteurizers with indirect heating for a pumping rate of 1 gallon/second are:

Table 14. Holding Tube Length - HHST Pasteurizers - Indirect Heating
Holding
Time
(sec.)
Tubing Size (inches)
22 ½3
Holding Tube Length (inches)
1.0 sec.168.0105.071.4
0.5 sec.84.052.435.7
0.1 sec.16.810.57.14
0.05 sec.8.45.243.57
0.01 sec.1.681.05.714

Procedure:

  1. Examine the entire system to ensure that all flow-promoting equipment is operating at maximum capacity and all flow-impeding equipment is so adjusted or bypassed to provide the minimum resistance to the flow. Remove in-line filters; make sure the booster pump is operating; and that vacuum equipment in the system is operating at the maximum vacuum. Also, before the Tests are begun, operate the pasteurizer at maximum flow for a sufficient time to purge the air from the system, about fifteen (15) minutes, and tighten the pipe connections on the suction side of the timing pump, tight enough to exclude the entrance of air. With the pasteurizer operating on water, adjust the timing pump to its maximum capacity, preferably with a new belt and full-size impellers.
  2. Determine that no flow exists in the diverted line, and measure the time required to deliver a known volume of water at the discharge of the pasteurizer in forward-flow. Repeat the Test determine that the measurements are consistent.
  3. Repeat Procedures 1 and 2 in diverted-flow by collecting the effluent at the discharge of the divert line.
  4. Select the greatest flow rate, the shortest delivery time for the known volume; and calculate the flow rate in gallons per second by dividing the known volume by the time required to collect the known volume. Multiply this value with the appropriate value in Table 14 to determine the required holding tube length.
  5. The holding tube may include fittings. The centerline length of the fitting is treated as an equivalent length of straight pipe. The centerline distance may be measured by forming a flexible steel tape along the centerline of the fitting. Determine the total length of the holding tube by adding the equivalent lengths of the fittings to the measured lengths of straight pipe. Record the number and type of fittings, the number and length of straight pipe and the holding tube configuration for the office record. If the temperature sensor is located at the beginning of the holding tube, the holding tube shall be protected against heat loss by material that is impervious to water.
  6. Re-seal the regulatory controls as necessary.

Alternate Procedure for Measuring Flow Rate: For pasteurizers of large capacity, the method of measuring flow rate at the discharge of the pasteurizer is inconvenient. The following alternate Test procedure may be used. Remove the divert line from the constant-level tank and turn off the milk or milk product pump feeding the constant-level tank. Suspend a sanitary dipstick in the constant-level tank and operate the pasteurizer at maximum capacity. Record the time required for the water level to move between two (2) graduations on the dipstick. The volume of water is calculated from the dimensions of the constant-level tank and the drop in water level. Flow rate is determined as follows: Divide the volume of water removed from the constant-level tank by the time, in seconds, required to remove it. Then use Table 14 to calculate the required holding tube length.

Alternate Procedures for Determination of Holding Tube Length for Non-Standard Pipe Size: The holding tube length may be accurately calculated from the following equation:

L = 588 Qt / D2

Where:

  • L = Holding tube length (inches)
  • Q = Pumping rate (gallons per second)
  • t = Holding time standard (seconds)
  • D = Inside diameter of holding tube (inches)

Table 15 provides internal pipe diameters for piping in HHST holding tubes with nominal external diameters of 2.0, 2.5, 3.0 and 4.0 inches.

NOTE: Internal diameters, for holding tubes designed for high pressure and for holding tubes with piping sizes not listed in Table 15, must be individually determined and the minimum length calculated using the above formula.

Table 15. Dimension for Standard Stainless Steel Sanitary Tubing1
Nominal External Diameter2Internal Diameter2
2.01.870
2.52.370
3.02.870
4.03.834

1 Abstracted from Table 6.1 “Pipe and Heat Exchanger Tube Dimensions”, Fundamentals of Food Process Engineering, 1979, R. T. Toledo, AVI Press
2 Measurements are in inches.

After the minimum required holding tube length is obtained from the calculation above, the length of the holding tube is measured to determine that it is at least as long as the calculated length. The holding tube may include fittings or, for the shorter holding times, may be a fitting. The centerline length of the fitting is treated as an equivalent length of straight pipe. The centerline distance may be measured by forming a flexible steel tape along the centerline of the fitting.

Corrective Action: If the length of the holding tube is shorter than the calculated length, reseal the timing pump at a slower maximum speed, or lengthen the holding tube, or both, and repeat this Procedure.
 

back to top

11.4 CALCULATED HOLD FOR DIRECT HEATING

Application: To all HHST pasteurizers using direct contact heating.

Frequency: When installed; semiannually thereafter; whenever the seal on the speed setting is broken; whenever any alteration is made affecting the holding time, the velocity of the flow, i.e., replacement of pump, motor, belt, driver or driven pulley, or a decrease in the number of heat exchange plates; or the capacity of the holding tube; and whenever a check of the capacity indicates a speedup.

Criteria: Every particle of milk or milk product shall be held for the minimum holding time in both forward and diverted-flow positions.

Apparatus: No supplemental materials needed.

Method: Fully developed laminar flow and a temperature increase by steam injection of 67°C (120°F) are assumed, the processor chooses the temperature-time standard and the required holding tube length is calculated from an experimental determination of the pumping rate.

Procedure:

  1. Examine the entire system to ensure that all flow-promoting equipment is operating at maximum capacity and all flow-impeding equipment is so adjusted or bypassed as to provide the minimum resistance to the flow. Remove in-line filters; make certain booster pumps are operating; and that vacuum equipment in the system is operating at maximum vacuum. Also, before the tests are begun, operate the pasteurizer at maximum flow for a sufficient time to purge the air from the system, about fifteen (15) minutes, and tighten the pipe connections on the suction side of the timing pump to exclude the entrance of air. With the pasteurizer operating on water, adjust the timing pump to its maximum capacity.
  2. Determine that no flow exists in the diverted line, and measure the time required to deliver a known volume of water at the discharge of the pasteurizer in forward-flow. Repeat the Test to determine that the measurements are consistent.
  3. Repeat Procedures 1 and 2 in diverted-flow by collecting the effluent at the discharge of the divert line.
  4. Select the greatest flow rate, the shortest delivery time for the known volume, and calculate the flow rate in gallons per second, by dividing the known volume, by the time required to collect the known volume. Multiply this value, with the appropriate value in Table 15 to determine the required holding tube length. Holding tube lengths for direct contact heating pasteurizers with a pumping rate of 1 gallon/second are:

    Table 16. Holding Tube Length, HHST Pasteurizers, Direct Heating
    Holding
    time
    (sec.)
    Tubing Size (inches)
    22 ½3
    Holding tube length (inches)
    1188.0118.080.0
    0.594.059.040.0
    0.118.811.88.0
    0.059.405.904.0
    0.011.881.180.8
  5. The holding tube may include fittings. The centerline length of the fitting is treated as an equivalent length of straight pipe. The centerline distance may be measured by forming a flexible steel tape along the centerline of the fitting. Determine the total length of the holding tube by adding the equivalent lengths of the fittings to the measured lengths of straight pipe. If the actual holding tube length is equivalent to or greater than the required holding tube length, record the number and type of fittings, the number and length of straight pipes and the holding tube configuration, for the office record. Make sure that the holding tube slopes upward at least 6.35 millimeters (0.25 inch) per foot. If the temperature sensor is located at the beginning of the holding tube, the holding tube shall also be protected against heat loss by material that is impervious to water.
  6. Re-seal the regulatory controls as necessary.

Alternate Procedure for Measuring Flow Rate: For pasteurizers of large capacity, the method of measuring flow rate at the discharge of the pasteurizer is inconvenient. The following alternate Test procedure may be used. Remove the divert line from the constant-level tank and turn off the milk or milk product pump feeding the constant-level tank. Suspend a sanitary dipstick in the constant-level tank and operate the pasteurizer at maximum capacity. Record the time required for the water level to move between two graduations on the dipstick. The volume of water is calculated from the dimensions of the constant-level tank and the drop in water level. Flow rate is determined as follows: Divide the volume of water, in gallons, removed from the constant- level tank by the time, in seconds, required to remove it. Then use Table 16 to calculate the required holding tube length.

Alternate Procedures for Determination of Holding Tube Length for Non-Standard Pipe Size: The holding-tube length may also be accurately calculated from the following equation:

L = (588 Qt x 1.12) / D2

Where:

  • L = Holding-tube length (inches)
  • Q = Pumping rate (gallons per second)
  • t = Holding time standard (seconds)
  • D = Internal diameter of holding tube (inches).
  • 1.12 = 12% expansion for steam

Table 15 provides internal pipe diameters for piping in HHST holding tubes with nominal external diameters of 2.0, 2.5, 3.0 and 4.0 inches.

NOTE: Internal diameters, for holding tubes designed for high pressure, and for holding tubes with piping sizes not listed in Table 15, must be individually determined and the minimum length calculated using the above formula.

After the minimum required holding tube length is obtained from the calculation above, the length of the holding tube is measured to determine that it is at least as long as the calculated length. The holding tube may include fittings or, for the shorter holding times, may be a fitting. The centerline length of the fitting is treated as an equivalent length of straight pipe. The centerline distance may be measured by forming a flexible steel tape along the centerline of the fitting.

Corrective Action: If the length of the holding tube is shorter than the calculated length, reseal the timing pump at a slower maximum speed, or lengthen the holding tube, or both, and repeat the Procedure.
 

back to top

11.5 HOLDING TIME - STEAM INFUSERS WITH STEAM PRESSURE RELIEF VALVE AND VACUUM CHAMBER ORIFICE USED IN PLACE OF A TIMING PUMP

Application: To all HHST pasteurizers using direct steam infusion heating and using a steam pop-off valve and a vacuum chamber orifice in place of a timing pump.

Frequency: Upon installation; every three (3) months thereafter; or when a regulatory seal has been broken.

Criteria: Every particle of milk or milk product shall be held for the minimum holding time in both forward and diverted-flow positions.

Apparatus: No supplemental materials needed.

Method:

  1. The steam infuser shell or feed line shall be equipped with a pressure relief valve. This pressure relief valve shall be located and sized so that the total pressure inside the infuser can never exceed the set point on this pressure relief valve.
  2. An orifice or restriction, permanently installed in a noticeable fitting, shall be placed in the holding tube just prior to the vacuum chamber. The opening in the orifice or restriction, shall be sized to ensure a minimum milk or milk product residence time at least as long as that specified in the chosen HHST standard.
  3. The size of the opening in the orifice or restriction and the setting of the pressure relief valve shall be determined by trial and error. Once an appropriate maximum flow rate has been determined and a legal minimum holding time has been calculated, both the restriction or orifice and the steam pressure setting on the pressure relief valve shall be sealed so that neither can be changed.
  4. The Regulatory Agency shall keep records of the orifice or restriction size. They shall also keep records of the location, size, setting and manufacturer of the pressure relief valve.

Procedure:

  1. Examine the entire system to ensure that all flow-promoting equipment is operating at maximum capacity and all flow-impeding equipment is so adjusted or bypassed as to provide the minimum resistance to the flow.
  2. The steam pressure in the infuser shall be raised to a level just below the pressure relief point on the valve.
  3. Any back-pressure valves or other variable restrictions in the holding tube shall be normally placed into the fully open position.
  4. All air bleeds to the vacuum chamber shall be closed so that the chamber will be operating under maximum vacuum.
  5. Before the Tests are begun, operate the pasteurizer at maximum flow for a sufficient time to purge the air from the system, about fifteen (15) minutes, and tighten the pipe connections to exclude the entrance of air.
  6. Determine that no flow exists in the diverted line, and measure the time required to deliver a known volume of water at the discharge of the pasteurizer in forward-flow.
  7. Repeat the Test to determine that the measurements are consistent.
  8. Repeat Procedures 1 through 5 in diverted-flow by collecting the effluent at the discharge of the divert line.
  9. Select the greatest flow rate, the shortest delivery time for the known volume, and calculate the flow rate in gallons per second, by dividing the known volume by the time required to collect the known volume.
  10. Multiply this value, gallons per second, with the appropriate value in Table 15 to determine the required holding tube length.
  11. Holding tube lengths for direct contact heating pasteurizers with a pumping rate of 1 gallon/second are specified in Table 15.
  12. The holding tube may include fittings. The centerline length of the fitting is treated as an equivalent length of straight pipe. The centerline distance may be measured by forming a flexible steel tape along the centerline of the fitting. Determine the total length of the holding tube by adding the equivalent lengths of the fittings to the measured lengths of straight pipe.
  13. Make sure that the holding tube slopes upward at least 6.35 millimeters (0.25 inch) per foot.
  14. If the temperature sensor is located at the beginning of the holding tube, the holding tube shall also be protected against heat loss by material that is impervious to water.
  15. If the actual holding tube length is equivalent to or greater than the required holding tube length, record the number and type of fittings, the number and length of straight pipes and the holding tube configuration for the office record.
  16. Re-seal the regulatory controls as necessary.

Corrective Action: If the length of the holding tube is shorter than the calculated length, reseal the timing pump at a slower maximum speed, or lengthen the holding tube, or both, and repeat the Test.
 

TEST 12.
THERMAL-LIMIT-CONTROLLER FOR CONTROL - SEQUENCE LOGIC

References: Items 16p (B) and (E)

Thermal-limit-controllers used with HHST and HTST pasteurizers that have the FDD located downstream from the regenerator and/or cooler and aseptic processing systems shall be tested by one (1) of the following applicable Tests at the frequency prescribed:
 

12.1 PASTEURIZATION AND ASEPTIC PROCESSING -INDIRECT HEATING

Application: To all HHST and HTST pasteurizers that have the FDD located downstream from the regenerator and/or cooler and aseptic processing systems using indirect heating. When testing aseptic processing systems, the "milk or milk product divert system" or "milk or milk product divert valve" or "acceptable control system" may be substituted for the "FDD" when it is referenced in this Test.

Frequency: Upon installation; every three (3) months thereafter; or when a regulatory seal has been broken.

Criteria: The pasteurizer, or aseptic processing equipment, shall not operate in forward-flow until the milk or milk product surfaces downstream from the holding tube have been sanitized, or in the case of aseptic processing equipment, sterilized. Upon start-up, surfaces shall be exposed to fluid at pasteurization temperature, or in the case of aseptic processing equipment, sterilizing temperature, for at least the required pasteurization or sterilization time. If any public health control causes the FDD to assume the diverted flow position due to incorrect temperature, pressure or flow, forward-flow shall not be re-achieved until the milk or milk product-contact surfaces downstream from the holding tube have been re-sanitized, or in the case of aseptic processing equipment, re-sterilized.

Apparatus: A constant temperature bath of water, or oil, and the test lamp from the pneumatic testing device described in Test 9.1 may be used to check the control-sequence logic of the thermal-limit-controller.

Method: The control-sequence logic of the thermal-limit-controller is determined by monitoring the electric signal from the thermal-limit-controller during a series of immersions and removals of the two (2) sensing elements from a bath heated above the cut-in temperature.

Procedure:

  1. Heat the water or oil bath to a constant temperature, a few degrees above the cut-in temperature on the thermal-limit-controller. Wire the test lamp in series with the signal from the thermal-limit-controller to the FDD. Some processors may have time delays built into their control logic in excess of that required for public health reasons. If so equipped, by-pass these timers or account for their effect in delaying forward-flow.
  2. Immerse the sensing element of the FDD in the bath, which is above the cut-in temperature. The test lamp should remain unlighted, i.e., diverted-flow. Leave the sensing element in the bath.
  3. Immerse the sensing element from the holding tube in the bath. The test lamp should light up, i.e., forward-flow after a minimum time delay of one (1) second for continuous-flow pasteurization systems. For aseptic processing systems no delay is required if the filed process includes a documented sterilization period.
  4. Remove the sensing element of the FDD from the bath. The test lamp should remain lighted, i.e., forward-flow.
  5. Remove the holding tube sensing element from the bath. The test lamp should turn off immediately, i.e., diverted-flow.
  6. Re-immerse the sensing element of the holding tube in the bath. The test lamp should remain unlighted, i.e., diverted-flow.
  7. Re-seal the regulatory controls as necessary.

Corrective Action: If the control-sequence logic of the thermal-limit-controller does not follow these Procedures, the instrument shall be reconfigured to conform to this logic.
 

back to top

12.2 PASTEURIZATION AND ASEPTIC PROCESSING-
DIRECT HEATING

Application: To all HHST and HTST pasteurizers that have the FDD located downstream from the regenerator and/or cooler and aseptic processing systems using direct contact heating. When testing aseptic processing systems, the "milk or milk product divert system" or "milk or milk product divert valve" or "acceptable control system" may be substituted for the "FDD" when it is referenced in this Test.

Frequency: Upon installation; every three (3) months thereafter; or when a regulatory seal has been broken.

Criteria: The pasteurizer, or aseptic processing equipment, shall not operate in forward-flow until the milk or milk product surfaces downstream from the holding tube have been sanitized, or in the case of aseptic processing equipment, sterilized. Upon start-up, surfaces shall be exposed to fluid at pasteurization temperature, or in the case of aseptic processing equipment, sterilizing temperature for at least the required pasteurization or sterilization time. If the milk or milk product temperature falls below the pasteurization or sterilization standard in the holding tube, forward-flow shall not be re-achieved until the milk or milk product-contact surfaces downstream from the holding tube have been re-sanitized, or in the case of aseptic processing equipment, re-sterilized.

Apparatus: A constant temperature bath of water, or oil, and the test lamp from the pneumatic testing device described in Test 9.1 can be used to check the control-sequence logic of the thermal-limit-controller.

Method: The control-sequence logic of the thermal-limit-controller is determined by monitoring the electric signal from the thermal-limit-controller during a series of immersions and removals of the three (3) sensing elements from a bath heated above the cut-in temperature.

Procedure:

  1. Heat a water or oil bath to a constant temperature, a few degrees above the cut-in temperature on the thermal-limit-controller. Wire the test lamp in series with the signal from the thermal- limit-controller to the FDD. Some processors have time delays built into their control logic, in excess of that required for public health reasons. If so equipped, bypass these timers or account for their effect in delaying forward-flow. Before performing this test, make sure the pressure switches, which must be closed to achieve forward-flow, have also been bypassed.
  2. Immerse the sensing element from the FDD in the bath that is above the cut-in temperature. The test lamp should remain unlighted, i.e., diverted-flow. Remove this sensing element from the bath.
  3. Immerse the sensing element, from the vacuum chamber, in the bath. The test lamp should remain unlighted, i.e., diverted-flow. Remove the sensing element from the bath.
  4. Immerse the two (2) sensing elements located at the vacuum chamber and the FDD, into the bath. The test lamp should remain unlighted, i.e., diverted-flow. Leave the two (2) sensing elements in the bath.
  5. Immerse the third sensing element located at the holding tube, into the bath. The test lamp should light up, i.e., forward-flow, after a minimum time delay of one (1) second for continuous- flow pasteurization systems. For aseptic processing systems no delay is required if the filed process includes a documented sterilization period.
  6. Remove the FDD sensing element from the bath. The test lamp should remain lighted, i.e., forward-flow.
  7. Remove the vacuum chamber sensing element from the bath. The test lamp should remain lighted, i.e., forward-flow.
  8. Remove the remaining, holding tube, sensing element from the bath. The test lamp should turn off, i.e., diverted-flow, immediately.
  9. Re-immerse the holding tube sensing element into the bath. The test lamp should remain unlighted, i.e., diverted-flow.
  10. Re-seal the regulatory controls as necessary.

Corrective Action: If the control-sequence logic of the thermal-limit-controller does not follow these Procedures, the instrument shall be reconfigured to conform to this logic.
 

TEST 13.
SETTING OF CONTROL SWITCHES FOR MILK OR MILK PRODUCT PRESSURE IN THE HOLDING TUBE

Reference: Item 16p (B) and (E)

Application: To all HHST pasteurizers and aseptic processing systems, which are capable of operating with product in forward-flow mode, with less than 518 kPa (75 psig) pressure in the holding tube. When testing aseptic processing systems, the "milk or milk product divert system" or "milk or milk product divert valve" or "acceptable control system" may be substituted for the "FDD" when it is referenced in this Test.

Frequency: Upon installation; every three (3) months thereafter; whenever the pressure switch seal is broken; and whenever the operating temperature is changed.

Criteria: The pasteurizer or aseptic processor shall not operate in forward-flow unless the product pressure in the holding tube is at least 69 kPa (10 psi) above the boiling pressure of the product.

Apparatus: A sanitary pressure gauge and a pneumatic testing device described in Test 9.1 can be used for checking and adjusting the pressure switch setting.

Method: The pressure switch is checked and adjusted so as to prevent forward-flow unless the milk or milk product pressure in the holding tube is at least 69 kPa (10 psi) above the boiling pressure of the milk or milk product.

Procedure:

  1. From Figure 45 determine the pressure switch setting necessary for the operating temperature, not the diversion temperature, being used in the process. Install the sanitary pressure gauge, of known accuracy, and the pressure switch sensing-element on the pneumatic testing device.
  2. Remove the seal and cover to expose the adjustment mechanism on the pressure switch. Place the test lamp in series with the pressure switch contacts or use some other method to monitor the cut-in signal.
  3. Apply air pressure to the sensing element and determine the pressure gauge reading at the cut-in point of the switch, which should turn on the test lamp. If the pressure switch is short circuited, the lamp will be lit before air pressure is applied.
  4. Determine that the cut-in pressure on the switch is equivalent to or greater than the required pressure from Figure 45. If adjustment is necessary, refer to the manufacturer's instructions.
  5. After adjustment, repeat the Test.
  6. When the results are satisfactory, seal the pressure switch setting and record the results for the office record.

For each HHST pasteurizer or aseptic processing system temperature, the milk or milk product pressure switch setting is as follows:
 

Chart of pressure switch settings at sea level (PSGI) for operating temperatures of 190 through 300 degrees F. Pressure switch settings start at 10 PSGI for 190 degrees F through 210 degrees F and then gradually increase up to more than 60 PSGI at 300 degrees F.

Figure 45. Pressure Switch Setting

This pressure setting shall be adjusted upward by the difference between the local normal atmospheric pressure and the atmospheric pressure at sea level.
 

back to top

TEST 14.
SETTING OF CONTROL SWITCHES FOR DIFFERENTIAL PRESSURE ACROSS THE INJECTOR

Reference: Item 16p (B) and (E)

Application: To all continuous flow pasteurizers and aseptic processing systems using direct contact heating. When testing aseptic processing systems, the "milk or milk product divert system" or "milk or milk product divert valve" or "acceptable control system" may be substituted for the "FDD" when it is referenced in this Test.

Frequency: Upon installation; every three (3) months thereafter; and whenever the differential pressure controller seal is broken.

Criteria: The pasteurizer or aseptic processor shall not operate in forward-flow unless the milk or milk product pressure drop across the injector is at least 69 kPa (10 psi).

Apparatus: A sanitary pressure gauge and a pneumatic testing device described in Test 9.1 can be used for checking and adjusting the differential pressure controller.

Method: Adjust the differential pressure switch to prevent forward-flow, unless the differential pressure across the injector is at least 69 kPa (10 psi).

Procedure:

  1. Remove both pressure sensing elements from their original locations on the pasteurizer, or aseptic processor. Install a sanitary pressure gauge of known accuracy and the pressure-sensing element, which is installed prior to the steam injection, on the pneumatic testing device.
  2. Leave the other pressure sensing element open to the atmosphere, but at the same height as the sensing element connected to the pneumatic testing device.
  3. Wire the test lamp in series with the differential controller microswitch or use the method provided by the instrument manufacturer to monitor the cut-in signal.
  4. Apply air pressure to the sensing element and determine, from the test lamp, the pressure gauge reading at the cut-in point of the differential pressure switch.
  5. The differential pressure cut-in on the controller shall be at least 69 kPa (10 psi). If adjustment is necessary, refer to the manufacturer's instructions.
  6. After adjustment, repeat the Test.
  7. When the results are satisfactory, seal the instrument and record the results for the office record.
     

TEST 15.
ELECTRO MAGNETIC INTERFERENCE FROM HAND-HELD COMMUNICATION DEVICES

Application: To all electronic controls used to assure compliance with public health safeguards on continuous flow pasteurization and aseptic processing equipment that are installed in milk plants where hand-held communication devices are used.

Frequency: Upon installation; alteration of the electronic controls; every three (3) months thereafter; and whenever the type or wattage of the hand-held communication device(s) used in that facility is changed. Once a hand-held communication device has been shown to cause a given electronic control device to react adversely, the Test does not have to be repeated every three (3) months using that specific hand-held communication device on the adversely affected electronic control device. If the electronic control device is altered or there is a change in the hand-held communication device used, the electronic control device would be required to be tested.

Criteria: The use of hand-held devices shall have no adverse effect on the public health safeguards.

Apparatus: One (1) hand-held device representing each make and model used in the facility. The device must be operating at maximum output, fully charged.

Method: By observing the actual effect of the hand-held communication device, it can be determined if that device can be used near that equipment without compromising a public health safeguard.

Procedure:

  1. Position the hand-held communication device 30.5 centimeters (12 inches) in front of the electronic control where the public health safeguard resides.
  2. Place the communication device in the "send" mode for five (5) seconds and observe the effect on the public health safeguards. There should be no adverse effect. An adverse effect is any change that may adversely affect a public health safeguard.
  3. If applicable, repeat the Test with the operator access door open
  4. Repeat the above Test for each hand-held communication device identified in the Apparatus Section.
  5. Repeat the Test for each electronic control used to regulate a pasteurization or aseptic processing public health safeguard.

For Example: For temperature set point, operate the pasteurizer or aseptic processor on water in diverted-flow in the "Product" mode, at a steady temperature within 3°C (5°F) of the lowest cut-in temperature. In this example, an adverse effect is defined as forward-flow movement of the FDD or any artificial increase in temperature.

Corrective Action: Have the facility check for shielding, grounding and other installation concerns and retest. Until a solution, acceptable to the Regulatory Agency, can be found that does not adversely affect the public health safeguards, the hand-held device may not be used in the area of the public health safeguards.
 

back to top