Dairy Establishment Inspection Manual – Chapter 18
C. Flow Diversion Device

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Test 10: Leakage Past Valve Seat(s)

Application:

To all Flow Diversion Devices used with HTST pasteurizers and HHST systems which use a dual stem valve assembly.

Frequency:

Upon installation and at least once every 6 months thereafter.

Criteria:

Raw milk must not leak past the Flow Diversion Device into pasteurized milk channels.

Apparatus:

Suitable tools for disassembly of Flow Diversion Device and sanitary piping.

Method:

Observe the valve seat(s) of the Flow Diversion Device for leakage.

Procedure:

  1. While operating the system with water, place the Flow Diversion Device in the diverted flow position.
  2. Disconnect the forward flow piping of a single stem device and verify that the valve seat does not leak. On a dual stem device, remove the leak detect pipe or observe carefully through the sight glass.
  3. Check the leak escape ports of a single stem device to ensure that they are open.
  4. Record results.

Corrective Action:

If leakage is noted, device must be dismantled and defective gaskets replaced or other suitable repairs made.

Test 11: Operation of Valve Stem(s)

Application:

To all Flow Diversion Devices used with HTST pasteurizers where a stem packing nut is used.

Frequency:

Upon installation and at least once every 6 months thereafter.

Criteria:

The Flow Diversion Device valve stem(s) move(s) freely when the stuffing box nut is fully tightened.

Apparatus:

Suitable tools for disassembly of Flow Diversion Device and sanitary piping.

Method:

Observe Flow Diversion Device valve stem(s) for ease of movement.

Procedure:

  1. Tighten the stuffing box nut as much as possible.
  2. Operate the HTST and place the Flow Diversion Device in forward and diverted flow several times.
  3. Observe that the Flow Diversion Device valve stem(s) move(s) with ease.
  4. Record results.

Corrective Action:

If valve action is sluggish, suitable adjustment or repair shall be made to permit stem to act freely in all positions, with packing nut, when used fully tightened.

Figure 2 - Valve Body Sub Assembly
Figure - Valve Body Sub Assembly. Description follows.
Description of image - This diagram shows the parts of the Valve Body Sub-Assembly.

It consists of:

  • 4" nut
  • Leak Detector Spring
  • Leak Detector O-Ring
  • Leak Detector Poppet
  • Upper Valve Body
  • Paper Gasket
  • Plunger Nut
  • Small Rubber Ring (2 ⅛" outer diameter (O.D.))
  • Ring Separating Disc
  • Large Rubber Ring (3 ¾" O.D.)

Reference: Milk Pasteurization Controls and Tests (Red cow book), 8th Edition, 2003.

Test 12: Device Assembly, Single Stem Device

Application:

To all single stem Flow Diversion Devices used with HTST pasteurizers.

Frequency:

Upon installation, at least once every 6 months thereafter and whenever the microswitch is re-set or replaced.

Criteria:

The Flow Control Device and all other flow promoting devices located between the constant level tank and the vacuum breaker stop or are isolated from the system when the Flow Diversion Device is improperly assembled.

Apparatus:

Sanitary fitting wrench.

Method:

Observe function of Flow Control Device when Flow Diversion Device is improperly assembled.

Procedure:

  1. With the system in operation with cold water and the Flow Diversion Device in diverted position unscrew by one-half turn, the 13H hex nut which holds the top of the valve to the valve body. This should de-energize the Flow Control Device and all other flow promoters. This test should be run with no piping connected to the forward flow port of the Flow Diversion Device since there can be sufficient force from the piping to keep the forward flow port tightly clamped even though the hex nut is loosened.
  2. With the system in operation with cold water and Flow Diversion Device in diverted position, remove the connecting key located at the base of the valve stem. The Flow Control Device and all other flow promoters should be de-energized.
  3. Record results.

Corrective Action:

If Flow Control Device fails to respond as indicated, immediate checks of the device assembly and wiring are required to locate and correct the cause.

contents

Test 13: Device Assembly, Dual Stem Device

Application:

To all dual stem Flow Diversion Devices used with HTST and HHST pasteurizers.

Frequency:

Upon installation, at least once every 6 months thereafter and when microswitch is re-set or replaced.

Criteria:

The Flow Control Device and all other flow promoters stops or by-passed when the Flow Diversion Device is improperly assembled.

Apparatus:

Tools to dismantle Flow Diversion Device.

Method:

Observe function of Flow Control Device and all other flow promoters when Flow Diversion Device is improperly assembled.

Procedure A:

  1. While the pasteurizer is not operating, with the Flow Diversion Device in diverted flow, remove one actuator clamp.
  2. Move the Flow Diversion Device to the forward flow position using the "Inspect" position of the selector switch and disconnect stem from actuator.
  3. Move the Flow Diversion Device to the diverted flow position using the "Process" position of the selector switch and turn on the Flow Control Device. The Flow Control Device and all other flow promoters should not run or bypassed.
  4. Reassemble the Flow Diversion Device by moving it to the forward flow position and reconnecting the stem to the actuator.
  5. Move the Flow Diversion Device to the diverted flow position and replace the actuator clamp.
  6. Repeat the procedure for the other actuator.
  7. Record results.

Procedure B:

  1. With the Flow Diversion Device in the diverted flow position, move the microswitch away from the contact groove in the valve stem. Observe that the Flow Control Device and all other flow promoting devices are stopped or by-passed.
  2. Record results.

Procedure C:

  1. With the pasteurizer system in forward flow, insert a nut into the diversion valve quick exhaust port.
  2. Reduce the processing temperature below the cut-out temperature.
  3. Observe that the diversion valve does not immediately move to the fully diverted position, that all flow promoters stop and separator is by-passed.
  4. Repeat the test for leak detect valve.
  5. Record the results.

Procedure D: (For systems with a Magnetic Flow Meter System used as a Flow Control Device)

  1. With the pasteurizer system in forward flow, insert a nut into the diversion valve quick exhaust port.
  2. Activate the high flow alarm.
  3. Observe that the diversion valve does not immediately move to the fully diverted position, that all flow promoters stop and separator is by-passed.
  4. Activate the low flow alarm or loss of signal alarm.
  5. Observe that the diversion valve does not immediately move to the fully diverted position, that all flow promoters stop and separator is by-passed.
  6. Repeat the test for leak detect valve.
  7. Record the results

Corrective Action:

If Flow Control Device fails to respond as indicated, an immediate check of the device assembly and wiring is required to locate and correct the cause.

Figure 3 - Value Exploded View
Figure - Value Exploded View. Description follows.
Description of image - Valve Exploded View

This schematic is a dual stem diversion device, exploded view. It shows the different parts of a dual stem flow diversion device, broken apart into the lower body, upper body, microswitch along with the control panel. The components include:

  1. Lower body - divert valve
  2. Valve plug assembly
  3. "O" Ring - Valve plug stem
  4. Clamp - body
  5. Gasket - body
  6. Body Assembly - valve
  7. Clamp - actuator
  8. Connector - hose
  9. Quick exhaust valve
  10. Nipple - pipe
  11. Actuator Assembly (complete)
  12. Upper body valve
  13. Actuator assembly
  14. "O" Ring - Base plate to housing
  15. Cable assembly
  16. Nut - Cable grommet
  17. Grommet - cable
  18. Acorn nut
  19. Washer
  20. Housing - microswitch
  21. Screw - cover bracket
  22. Lockwasher - cover bracket
  23. Screw - Microswitch bracket
  24. Bracket cover
  25. Loop clamp
  26. Screw - Loop clamp
  27. Screw - Microswitch Adjusting
  28. Spring
  29. Bracket - Microswitch
  30. Bracket - Microswitch Adjusting
  31. Block - Microswitch mounting
  32. Microswitch
  33. Washer
  34. Screw - microswitch
  35. Control panel (complete)

Reference: Milk Pasteurization Controls and Tests (Red cow book), 8th Edition, 2003.

List: Dual Stem Flow Diversion Device Tri-Clover Model 262-121
Key Description

  1. Lower Body - Divert Valve
  2. Valve Plug Assembly
  3. "O" Ring - Valve Plug Stem
  4. Clamp - Body
  5. Gasket - Body
  6. Body Assembly - Valve
  7. Clamp - Actuator
  8. Connector - Hose
  9. Quick Exhaust Valve
  10. Nipple - Pipe
  11. Actuator Assembly (Complete)
  12. Upper Body - Valve
  13. Actuator Assembly
  14. "O" Ring - Base Plate To Housing
  15. Cable Assembly
  16. Nut - Cable Grommet
  17. Grommet - Cable
  18. Acorn Nut
  19. Washer
  20. Housing - Microswitch
  21. Screw - Cover Bracket
  22. Lockwasher - Cover Bracket
  23. Screw - Microswitch Bracket
  24. Bracket - Cover
  25. Loop Clamp
  26. Screw - Loop Clamp
  27. Screw - Microswitch Adjusting
  28. Spring
  29. Bracket - Microswitch
  30. Bracket - Microswitch Adjusting
  31. Block - Microswitch Mounting
  32. Microswitch
  33. Washer
  34. Screw - Microswitch
  35. Control Panel (Complete)

Test 14: Manual Diversion

Application:

HTST system with a booster pump.

Frequency:

Upon installation and at least once every 6 months thereafter.

Criteria:

When Flow Diversion Device is manually diverted, booster pump stops, frequency pen records a diverted flow position, green light goes out, red light comes on and pressure differential is maintained.

Apparatus:

None.

Method:

Observe the response of the system to manual diversion.

Procedure:

  1. With HTST system in operation and the Flow Diversion Device in the forward flow position, press the manual diversion button. Observe that the flow diversion valve assumes the divert position, and the booster pump stops. The frequency pen should record a diverted flow position, and the green light goes out while the red light comes on. The pressure differential between raw and pasteurized milk in the regenerator should be maintained.
  2. Activate the manual button while operating the HTST system at its maximum operating pressure. Confirm that the spring tension of the Flow Diversion Device is capable of diverting the system at maximum operating pressure.
  3. Operate the HTST system in forward flow and activate the manual divert button until the raw side pressure reaches zero (0) psi. Release the manual divert button and observe that the pressure differential between raw and pasteurized milk in the regenerator is maintained.
  4. Record the results.

Corrective Action:

If the above described actions do not occur when procedures 1,2 and 3 are performed, or the necessary pressure differential between raw and pasteurized milk is not maintained, the assembly and wiring of the HTST system must be immediately reviewed and the indicated deficiencies corrected or proper adjustments made.

Test 15: Response Time

Application:

To all Flow Diversion Devices used with HTST pasteurizer and HHST systems which use a dual stem valve assembly.

Frequency:

Upon installation and at least once every 6 months thereafter.

Criteria:

The Flow Diversion Device moves from the fully forward to the fully diverted position in no more than one second.

Apparatus:

  1. Stopwatch.
  2. Water, oil or other suitable media bath.

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 Flow Diversion Device takes the fully diverted flow position.

Procedure:

  1. Place the temperature sensing probe of the Safety Thermal Limit Recorder into the water, oil or other suitable media bath.
  2. With water, oil or other suitable media bath at a temperature above cut-out temperature, allow the water, oil or other suitable media to cool gradually. At the moment the cut-out mechanism is activated, start the watch and the moment the Flow Diversion Device takes the fully diverted position, stop the watch. On a dual stem device, both valves should move simultaneously.
  3. Record results. The response time interval must not exceed one second.

Corrective Action:

Should response time exceed 1 second, immediate corrective action must be taken.

Test 16: Valve Flush Time Delay

Application:

To all dual stem flow diversion devices in which product may be pocketed between the two valve seats while the valve is in diverted flow position (applicable to HTST only).

Frequency:

  1. Upon installation and at least once every 6 months thereafter.
  2. Whenever the seal on the time delay relay is broken.

Criteria:

There shall be a flush of the transitional cavity between the two valves of at least one (1) second. If a restrictor is installed in the divert line, the delay shall be no longer than three (3) seconds. The maximum three seconds of delay is not applicable when the timing system is magnetic flow meter based.

Apparatus:

Stopwatch.

Method:

When the flow diversion device moves from the diverted flow position to the forward flow position, the cavity located between the two valve bodies shall receive an adequate flush to remove stale product, but this flush should not compromise the required hold time.

Procedure:

  1. Operate the pasteurizer in diverted flow position.
  2. Raise the temperature to a point above the cut-in temperature.
  3. At the instant the divert (first) valve begins to move into its "forward flow" position, start the stopwatch.
  4. At the instant the leak detect valve begins to move, stop the stopwatch.
  5. Record the result and adjust the time delay relay if necessary (and seal the time delay relay or its enclosure).

Corrective Action:

Should the valve flush time be less than one (1) second and greater than three (3) seconds in restrictor installed divert line, immediate corrective action must be taken.

Test 17: Time Delay Interlock With Flow Control Device

Application:

To dual stem Flow Diversion Devices with a manual forward flow switch (inspect position on the mode switch) (applicable to HTST and HHST pasteurizers).

Frequency:

Upon installation and at least once every 6 months thereafter.

Criteria:

To verify that the system cannot enter a manually induced forward flow position while the Flow Control Device is running or any flow promoting device located between the constant level tank and the vacuum breaker is active.

Apparatus:

None.

Method:

Determine that the Flow Diversion Device does not assume a manually induced forward flow position while Flow Control Device is running or any flow promoting device located between the constant level tank and the vacuum breaker is active.

Procedure:

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

  1. The Flow Diversion Device immediately moves to the diverted flow position and the Flow Control Device is turned off.
  2. The Flow Diversion Device remains in the diverted flow position while the Flow Control Device is running down.
  3. All flow promoting devices are either de-energized or by-passed.
  4. After the Flow Control Device stops running, the Flow Diversion Device assumes the forward flow position. All flow promoting devices remain de-energized or by-passed.
  5. Record results and seal the timer or enclosure.

Corrective Action:

If the above sequence of events does not occur, either a timer adjustment or wiring change is required.

Test 18: CIP Time Delay Relay

Application:

To all HTST and HHST pasteurizer systems in which it is desired to run the Flow Control Device and/or other flow promoting device during the CIP cycle.

Frequency:

  1. Upon installation and at least once every 6 months thereafter.
  2. Whenever the seal on the time delay relay is broken.

Criteria:

When the mode switch on the Flow Diversion Device is moved from "Process Product" to "CIP", the Flow Diversion Device shall move immediately to the diverted position and remain in the diverted position for at least 10 minutes before starting its normal cycling in the CIP mode. In HTST systems the booster pump shall be turned off and shall not run during the 10 minute time delay.

Apparatus:

Stopwatch.

Method:

Adjust the set point on the time delay relay equal to or greater than 10 minutes.

Procedure:

  1. Operate pasteurizer in forward flow with the mode switch on the Flow Diversion Device in the "Process Product" position, at a flow rate below the value at which holding time was measured, using water above pasteurization temperature.
  2. Move the mode switch on the Flow Diversion Device to the "CIP" position. The Flow Diversion Device shall move immediately to the diverted position and the booster pump shall stop running.
  3. Start the stopwatch when the Flow Diversion Device moves to the diverted position.
  4. Stop the stopwatch when the Flow Diversion Device moves to the forward flow position for its initial cycle in the CIP mode or when the booster pump starts.
  5. Record results. The time delay must be at least 10 minutes.

Corrective Action:

If the Flow Diversion Device does not remain in the diverted position for at least 10 minutes after the mode switch is moved from "Process Product" to "CIP", increase the set point on the time delay relay and repeat this test procedure. If the booster pump runs at any time during the 10 minute delay, the booster pump wiring is in need of repair.

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