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SEAT ASSEMBL

Y

SEAL RING

O-RING

(BOLT)

SEAL RETAINER

WASHER

BOLT

CHECK HANDLE

 

O-RING (SEAT

)

Maintenance Instructions

WILKINS, a ZURN  company

1747 Commerce Way, Paso Robles, CA 93446 Phone:805/238-7100 Fax:805/238-5766

3

a              company

®

®

CHECK  ASSEMBLY

All Model 450 Double Check Valve Backflow Preventers must be 

inspected and maintained by licensed personnel at least once 

a year or more frequently as specified by local codes. Replace

-

ment of worn or damaged parts must only be made with genuine 

“WILKINS” parts.

GENERAL MAINTENANCE

1. Clean all parts thoroughly with water after disassembly.

2. Carefully inspect rubber seal rings and o-rings for damage.   

3. Test unit after reassembly for proper operation (refer to 

  “TESTING PROCEDURES”).

SERVICING CHECK VALVES

1. Close the outlet and then the inlet shut-off valves.

2. Open No. 2, 3 and 4 test cocks to release internal pressure.   

  Leave them open during check removal and reinstallation.

3. Loosen and remove the two nuts, bolts, gasket and grooved  

  coupling from around the access cover.

4. If the valve has a wire retainer on the #1 check assembly,    

   pinch together the exposed ends, pull toward the #2 check 

  and remove from valve.

5. If the valve has a plastic retainer on the #1 check, grasp one  

  of the  exposed ends, push down and then pull toward the #2  

  check. The retainer should “spiral” out of the groove around   

  the check.

6. Remove the #2 check by locating one of the two spring-loaded

  plate retainers around the face of the check. Pinch the sides

  of the spring together and rotate the plates out of the body   

  groove one at a time. Remove the 2

nd

 retainer the same way.

7. 

Always service the checks one at a time to avoid mixing

  

 

parts.

 Start by removing the hardware and o-rings from the 

  back of the check assembly (See “Check Assembly” illustra-  

  tion). Separate the seal retainer from the assembly to expose   

  the seal ring.

8. Inspect the seal ring for cuts or embedded debris. If the reverse  

     side of the seal is unused, the seal ring can be inverted and   

  used temporarily until a new seal is obtained. Inspect seat    

  o-ring and replace if cut or damaged in any way.

9. Inspect valve cavity and seating areas. Flush with water to

  remove any debris.

10.Reassembly: Lubricate the #2 check o-ring, install in the body          

     and close the #4 test cock. Install the #2 check retainers 

     into the body groove one plate at a time, squeezing the  

 

    spring ends together to clear the stops on the face of the seat. 

    Lubricate and install the #1 check, close the #2 test cock and  

    install:

    (A) wire retainer by pinching the ends together, placing the    

    lower edge of the ring into the body groove below the check 

    and rotating the top of the ring into the notch above the check.

    (B) plastic retainer by inserting the end with short tab into the  

    notch above the check, sliding your hand around the face of   

     the retainer pushing it into the groove as you go. Retainer    

    should “snap” into place.

11.Lubricate the outside surface of the grooved coupling gasket 

    Reassemble access cover and grooved coupling, making        

     sure the ends of the coupling touch each other. Close any    
    remaining open test cocks and place valve back in service.

SPECIFICATIONS

Maximum working water pressure: 

175 PSI

Maximum working water temperature:  140°F
Hydrostatic test pressure:    

350 PSI

End connections:   

 

Grooved AWWA C606

Capacity thru Schedule 40 Pipe

Pipe size 5 ft/sec 7.5 ft/sec 10 ft/sec 15 ft/sec

2 1/2"

75

112

149

224

3"

115

173

230

346

4"

198

298

397

595

6"

450

675

900

1351

8"

780

1169

1559

2339

10"

1229

1843

2458

3687

FIGURE 1

FIGURE 2

FIGURE 3

WIRE RETAINER

#1 CHECK ASSEMBL

Y

ACCESS COVER

GROOVED COUPLING

          

ASSEMBL

Y

#1 CHECK

ASSEMBLY

STEM

PLATE RETAINER

#2 CHECK ASSEMBLY

Summary of Contents for WILKINS 450

Page 1: ...e adequate space around the installed unit so that the test cocks will be accessible for testing and servicing 3 Install valve at least 6 inches above surrounding flood level 4 Always consult local codes for installation methods approvals and guidance PLACING THE DEVICE IN SERVICE 1 Start with both shut off valves closed Slowly open the inlet shut off valve until the backflow preventer is complete...

Page 2: ...valve 1 after gauge reading stabilizes and water stops running out of test cock 3 5 Close all test cocks open shut off valve 1 and remove test equipment TEST NO 2 TIGHTNESS OF 2 CHECK VALVE REQUIREMENT The static pressure drop across check valve 2 shall be at least 1 0 psid If test cock 4 is not at the highest point of the check valve body then a vertical tube must be installed on test cock 4 so t...

Page 3: ...he back of the check assembly See Check Assembly illustra tion Separate the seal retainer from the assembly to expose the seal ring 8 Inspect the seal ring for cuts or embedded debris If the reverse side of the seal is unused the seal ring can be inverted and used temporarily until a new seal is obtained Inspect seat o ring and replace if cut or damaged in any way 9 Inspect valve cavity and seatin...

Page 4: ...c testing according to WILKINS specifications and prevailing governmental industry standards and codes and upon following these installation instructions Failure to do so releases WILKINS of any liability that it might otherwise have with respect to that device Such failure could also result in an improperly functioning device PROBLEM POSSIBLE CAUSES CORRECTIVE ACTION 1 LEAKING CHECK VALVES 1 Debr...

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