How To Install A Wilkins Backflow Preventer
INSTALLATION & MAINTENANCEMODEL 375 65-250mm
INSTALLATION INSTRUCTIONS
Caution: Installation of Backflow Preventers must be performed past qualified, licensed personnel. The installer should exist sure the proper device has been selected for the particular installation. Faulty installation could effect in an improperly functioning device.
- ZURN WILKINS Model 375 Serial Reduced Force per unit area Principle assemblies are for use on drinkable water lines where a health hazard exists in the event of a backflow state of affairs
- Damage to the device could result wherever water hammer and/or water thermal expansion could create excessive line pressure level. Where this could occur, stupor arrestors, check valves and/or pressure relief valves should be installed downstream of the device.
- If installation is in a pit or vault, the Backflow Preventer must never be submerged in water considering this could cause across-connection. Make sure that the pit or vault always remains dry by providing aplenty drainage.
i. Before installing a Model 375 Backflow Preventer, flush the line thoroughly to remove all droppings, fries and other foreign matter. If required, a strainer should be placed upstream of the Backflow Preventer.
Circumspection: Do not apply a strainer in seldom
two. Provide acceptable infinite around the installed unit of measurement so that the test cocks volition be accessible for testing and servicing.
three. Install valve at least 300mm above surrounding flood level.
4. Always consult local codes for installation methods, approvals and guidance.
5. Resilient seated shutoff valves are required to be installed on both the inlet and outlet of the device to make field testing possible.
PLACING THE DEVICE IN SERVICE
1. Outset with both shut-off valves airtight. Slowly open the inlet shut-off valve until the backflow preventer is completely pressurized. A cursory discharge from the relief valve may occur while the device is pressurizing. The belch should end by the fourth dimension the close-off valve is fully open. If the discharge does not stop, refer to "MAINTENANCE INSTRUCTIONS" for repair procedures.
2. When the unit has been pressurized, vent any trapped air by slightly opening each of the four exam cocks
3. Slowly open the downstream shut-off valve. The G Model 375Series Reduced Pressure Principle device is now in service.
4. If spitting or intermittent discharges from the relief valve are noted, it could be a effect of pressure level fluctuation and/or a water hammer condition in the system. If such weather be, install water pressure reducing valves or h2o hammer daze arrestors in compliance with industry standards equally needed.
5. After the Model 375 has been properly installed, exam the device(come across "TEST PROCEDURES"). If the device fails the exam, remove the first and second check valves and thoroughly flush the device. If the relief valve fails to operate properly, inspect the sensing passage for clogging (see "MAINTENANCE INSTRUCTIONS"). Clean rubber seals of all debris and place unit back in service.
Functioning
STANDARDS COMPLIANCE
- Australian Watermark (AS/NZS 2845.one) Canonical Lic. 1379
- Type Tested AS/NZS 4020 Lic. 20221
OUTDOOR INSTALLATION: The Model 375Backflow Preventer may be installed outdoors only if the device is protected against freezing conditions. Exposure to freezing conditions will result in improper function or damage to the device. The installation location must be kept to a higher place 0°C. All the bones installation instructions apply
WARRANTY: ZURN WILKINS Valves are guaranteed against defects of cloth or workmanship when used for the services recommended. Please refer to the LWG Zurn/ Zurn Wilkins Production Warranty Argument for details.
TESTING PROCEDURES
TEST NO. 1 - RELIEF VALVE OPENING POINT
REQUIREMENT: The differential pressure relief valve must operate to maintain the zone between the two check valves at least 14kPa less than the supply pressure.
Procedure:
1. Flush water through test cocks #1, #ii (open #2 slowly), #3 and#4 past opening and closing each examination cock i at a time, to eliminate foreign material.
2. Install advisable fittings to exam cocks. Attach hose from the high side of the differential pressure gauge to the #2 test cock and then attach hose from the low side of the estimate to the #3 test cock. Open up examination cock #3 slowly then bleed all air from the hose and gauge by opening the low side bleed needle valve.
3. Maintain the low side bleed needle valve in the open position while test cock #2 is opened slowly. Open the loftier side drain needle valve to bleed all air from the hose and gauge. Shut the high side bleed needle valve, so close the low side bleed needle valve subsequently the approximate reading has reached the upper finish of the scale.
4. Close the #2 shut-off valve. If the gauge reading drops to the low finish of the judge calibration and the differential pressure relief valve discharges continuously, then the #1 bank check valve is leaking. If this occurs, Tests #i, #two and #3 cannot be com- pleted (See USC Maintenance Guide). Nonetheless, should the estimate reading remain higher up the differential pressure relief valve opening point, the nob serve the guess reading. This is the credible pressure drop across the #1 check valve.
5. Open the high side control needle valve approximately one turn, and and then open the low side command needle valve no more than1/4 turn to by-laissez passer water from the #ii exam erect to the #3 test cock. Observe the differential pressure reading as it slowly drops to the relief valve opening indicate. Record this opening point value when the first discharge of water is detected. Close the depression side needle valve.
TEST NO. two - TIGHTNESS OF #2 Cheque VALVE
REQUIREMENT: The #2 check valve shall be tight against backpressure
Procedure:
one. Maintain the #2 shut-off valve in the airtight position (from Test#one). Vent all air through the vent hose by opening the vent needle valve. Close the vent needle valve only (The high side control needle valve is to remain open.).
2. Attach the vent hose from the gauge to the #4 exam cock, and so open up the #iv test cock. Bleed water from the zone past opening the low side drain needle valve on the gauge order to re-establish the normal reduced pressure within the zone. Once the guess reading reaches a value above the #1 bank check valve pressure drop, close the depression side bleed needle valve.
three. Open the vent needle valve. If the indicated differential pressure reading remains steady then the #ii cheque valve is reported as "closed tight." Get to Test #iii. If the differential pressure reading falls to the relief valve opening signal, drain water through the low side bleed needle valve until the gauge reading reaches a value above the #1 bank check valve pressure drop. If the judge reading settles above the relief valve opening betoken, record the #2 check valve every bit "closed tight," and proceed to Exam #3. If the differential pressure reading falls to the relief valve opening indicate over again, then the #2 check valve is noted as "leaking," and Test #3 cannot be completed. If the differential pressure reading drops, but stabilizes above the relief valve opening indicate, the #2check valve tin can notwithstanding be reported as "closed tight."
NOTE: Due to disc compression, you may need to drain off h2o through depression side bleed needle valve several times before the approximate reading volition settle in a higher place relief valve opening point.
TEST NO. iii - TIGHTNESS OF #ane CHECK VALVE
REQUIREMENT: The static pressure drop across #one check valve shall exist greater than the relief valve opening indicate (test #1), and at least 35kPa
PROCEDURE:
1. With the vent hose connected to test erect #4 as in stride 3 of Test #ii, bleed water from the zone through the depression side bleed needle valve on the gauge until the reading exceeds the #1check valve pressure driblet. Close the low side bleed needle valve. After the gauge reading settles, the steady state differential pressure reading indicated (reading is not falling on the judge) is the bodily static (i.e., no menses) force per unit area drop across check valve #1 and is to be recorded as such.
ii.Close all test cocks, slowly open shutoff valve #ii and remove equipment.
CHECK Assembly
SERVICING Check VALVES
A ratchet wrench, 17mm deep socket, and a 100mm long extension are recommended for removing check assemblies.
1. Close inlet and outlet shut-off valves.
2. Open up No. 2, No. three and No. four test cocks to release pressure from valve.
3. Loosen & remove the grooved coupling effectually the access embrace. Remove cover. Place towel or cardboard over relief valve port in body to prevent parts from falling into relief valve.
4. To service only the #one check assembly, remove the 6 bolts, washers and o-rings from the back of the #i bank check assembly. Separate the retainer and the seal ring from the check associates and proceed to step #viii.
5. To service both checks or the #2 check, the #1 cheque assembly must start be removed. Remove the 4 nuts and washers retaining the #one check assembly. Remove the #ane check associates from the body.
6. To remove the #2 check assembly, remove the seven nuts, washers and the #two bank check retaining ring. Grasp the bank check assembly past the stem and remove from valve.
7. Remove all 6 bolts, washers and o-rings from the check assembly (See "Check Assembly" illustration). Split retainer from cheque associates to betrayal seal ring for inspection.
8. Audit the condom seal ring for cuts or embedded droppings. If the opposite side of the seal ring is unused, it is possible to invert the seal ring. This would be considered a temporary solution to fixing a fouled bank check and should be replaced with a new seal band as soon as possible.
nine. Audit valve cavity and seating areas. Remove any droppings.
10. Reverse the above procedures to reinstall check assemblies. Lubricate seat o-rings to hold them in place while reinstalling seat. Place washers on studs and tighten retaining nuts evenly.
11. Remove towel or paper-thin covering from relief valve port. Reinstall admission cover and grooved coupling.
Note: If any portion of the seat assembly is damaged or missing or if the seat sealing rib is damaged in any mode, do not attempt to field repair it. Contact The states for aid.
GENERAL MAINTENANCE
1. Clean all parts thoroughly with h2o later disassembly.2. Carefully audit prophylactic seal rings and o-rings for harm.3. Test unit after reassembly for proper operation (refer to "TESTING PROCEDURES").
RELIEF VALVE ASSEMBLY
SERVICING CHECK VALVES cont'd
TROUBLESHOOTING
(" Why is my backflow preventer leaking: ")
PROBLEM #1
SUDDEN OR RAPID SPITTING
POSSIBLE CAUSES
one. Drop in inlet force per unit area
2. Sudden increment in downstream pressure due to water hammer from quick closing close-off valve.
Corrective ACTION
ane. Install an in-line spring loaded check valve or force per unit area reducing valve upstream of Backflow Preventer.
2. Install an in-line spring loaded check valve or pressure reducing valve downstream of Backflow Preventer.
PROBLEM #2
Calorie-free OR INTERMITTENT DRIP
POSSIBLE CAUSES
ane. Slightly fouled #1 check.
2. Slightly fouled relief valve seat.
CORRECTIVE ACTION
i. Clean #ane check and/or turn cheque valve seal ring over or replace.
ii. Clean relief valve seat and/or turn relief valve seal ring over or supervene upon.
Problem #iii
CONTINUOUS DISCHARGE
POSSIBLE CAUSES
1. Fouled #i check and/or #two bank check.
2. Fouled relief valve seat.
CORRECTIVE Activity
ane. Make clean check valves and/or turn check valve seal ring over or replace.
ii. Make clean relief valve seat and/or turn relief valve seal ring over or replace.
For more data or additional support please contact us.
Source: https://www.deeco.co.nz/support/wilkins-backflow-preventers-model-375-installation-maintenance
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