Model 350XL, 350AXL LEAD-FREE*

Double Check Valve Assembly (2-1/2", 3", 4" & 6")

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company

Model 450XL

(Patent No. 5,913,331)

Double Check Valve Assembly (2-1/2" & 3")

*This product contains a weighted average lead content less than 0.25% for wetted surfaces, and is no-lead law compliant.



Installation  Testing  Maintenance Instructions

INSTALLATION INSTRUCTIONS PLACING THE DEVICE IN SERVICE

CAUTION: Installation of Backflow Preventers must be performed by qualified, licensed personnel. The installer should be sure the proper device has been selected for the particular installation. Faulty installation could result in an improperly functioning device.

WILKINS Model 350XL/450XL Series Assemblies are for use on potable water lines where a health hazard does not exist in the event of a backflow situation.

Damage to the device could result wherever water hammer and/or water thermal expansion could create excessive line pressure. Where this could occur, shock arrestors, check valves and/or pressure relief valves should be installed downstream of the device.

1. Start with both shut-off valves closed.

Slowly open the inlet shut-off valve until the backflow preventer is completely pressurized.

2. When the unit has been pressurized, vent any trapped air by slightly opening each of the four test cocks.

3. Slowly open the downstream shut-off valve. The Model 350XL/450XL Series Assembly is now in service.

If installation is in a pit or vault, the Backflow Preventer must never be submerged in water because this could cause a cross-connection. Make sure that the pit or vault always remains dry by providing ample drainage.

1. Before installing a Model 350XL/450XL Series Backflow Preventer, flush the line thoroughly to remove all debris, chips and other foreign matter. If required, a strainer should be placed upstream of the Backflow Preventer. CAUTION: Do not use a strainer in seldom used emergency waterlines such as fire lines.

2. Provide adequate space around the installed unit so that the test cocks will be accessible for testing and servicing.

3. Install valve at least 12 inches above surrounding flood level.

4. Always consult local codes for installation methods, approvals and guidance.

4. After the Model 350XL/450XL Series has been properly installed, test the device

(see “TEST PROCEDURES”). If the device fails the test, remove the first and second check valves and thoroughly flush the device. Clean rubber and seats of all debris and place unit back in service.

PROTECTIVE

ENCLOSURE PROTECTIVE

ENCLOSURE

12" MIN.

30" MAX.

DIRECTION OF FLOW

DIRECTION OF FLOW

OUTDOOR INSTALLATION

Model 450XL (2 1/2” & 3”)

OUTDOOR INSTALLATION

The Model 350XL/450XL Series Backflow Preventer may be installed outdoors only if the device is protected against freezing conditions. Exposure to freezing c onditions will result in improper function or damage to the device. The installation location must be kept above 32°F. All the basic installation instructions apply.

OUTDOOR INSTALLATION

Model 350XL

INDOOR INSTALLATION

Indoor installation is preferred in areas that are subject to freezing conditions. All the basic installation instructions apply to such installations.

Proposition 65 Warning This product contains chemicals known to the State of California to cause cancer and birth defects or other reproductive harm.

a

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WILKINS, a ZURN Company

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

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Testing Procedures

MODEL 350XL/450XL SERIES ASSEMBLY

Equipment Required: Differential pressure gauge test kit.

TEST NO. 1 - TIGHTNESS OF #1 CHECK VALVE

REQUIREMENT:

The static pressure drop across check valve #1 shall be at least

1.0 psid. If test cock #3 is not at the highest point of the check valve body, then a vertical tube must be installed on test cock #3 so that it rises to the top of the check valve body.

PROCEDURE:

1. Slowly open all 4 test cocks to remove any foreign material

and attach fittings.

2. Attach hose from the high side of the test kit to the #2 test cock.

3. Open test cock #2 and bleed all air from the hose and gauge

by opening the high side bleed needle valve. Close high side

bleed needle valve. If a tube is attached to test cock #3, open

test cock #3 to fill the tube. Close test cock #3. Close #2

shut-off valve then close the #1 shut-off valve.

4. Hold gauge at same level as test cock #3 or water level in

tube. Slowly open test cock #3. Record the static pressure

drop across check 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.

Note: If you are using the duplex gauge method to test the valve, you may see both needles drop simultaneously during test due to disc compression. The high side needle should eventually hold

2 psi below low side needle if check in not fouled.

#3 TEST COCK

#2 TEST COCK

#4 TEST COCK

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 that it rises to the top of the check valve body.

PROCEDURE:

1. Attach hose from the high side of the test kit to the #3 test cock.

2. Open test cock #3 and bleed all air from the hose and gauge

by opening the high side bleed needle valve. Close high

side bleed needle valve. If a tube is attached to test cock

#4, open test cock #4 to fill the tube. Close test cock #4.

Close #1 shut-off valve.

3. Hold gauge at same level as test cock #4 or water level in

tube. Slowly open test cock #4. Record the static pressure

drop across check valve #2 after gauge reading stabilizes and

water stops running out of test cock #4.

4. Close all test cocks, slowly open shut-off valve #1 & #2 and

remove test equipment.

SPECIFICATIONS

Maximum working water pressure: 175 PSI

Maximum working water temperature: 140°F

Hydrostatic test pressure: 350 PSI

End connections: Flanged ANSI B16.1 Class 125

Grooved AWWA C606

CHECK ASSEMBLY

O-RING (SEAT)

SEAT ASSEMBLY

(2-1/2” - 3”)

#1 TEST COCK

O-RING

WASHER

SEAL RING

SEAL RETAINER

#1 SHUT-OFF

VALVE

HIGH SIDE BLEED

NEEDLE VALVE

LOW SIDE BLEED

NEEDLE VALVE

#2 SHUT-OFF

VALVE

LOW SIDE HOSE

O-RING (SEAT)

NUT

HIGH SIDE HOSE SEAT ASSEMBLY

VENT HOSE

O-RING

(BOLT)

WASHER

2

Pipe size

2-1/2"

3"

4"

6"

8"

10"

Capacity thru Schedule 40 Pipe (GPM)

5 ft/sec

75

115

198

450

780

1129

7.5 ft/sec 10 ft/sec 15 ft/sec

112

173

298

675

1169

1843

149

230

397

900

1559

2458

224

346

595

1351

2339

3687

Repair Kits

SIZE

2-1/2" - 3"

4"

6"

SEAL RING

SEAL RETAINER

CHECK HANDLE

BOLT

4” - 6”

MODEL 350XL RUBBER ONLY

RK212-350

RK4-350

RK6-350 a

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company

WILKINS, a ZURN Company

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

Maintenance Instructions

All Model 350XL/450XL Series Backflow Preventers must be inspected and maintained by licensed personnel at least once a year or more frequently as specified by local codes. Replacement 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”).

NOTE: If any portion of the seat assembly is damaged or missing or if the seating surface is damaged in any way, do not attempt to field repair it. Contact your local WILKINS representative for assistance.

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 and gasket from the grooved coupling 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. (2-1/2 – 3” Models) Remove the #2 retainer and check in the same manner as the #1.

GASKET

7. (4 – 6” Models) 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.

8. 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” illustration). Separate the seal retainer from the assembly to expose the seal ring.

9. 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. (2 1/2” & 3” Models)

Tighten check assembly nut between 20-25 ft/lbs of torque. Inspect seat o-ring and replace if cut or damaged in any way.

10. Inspect valve cavity and seating areas. Flush with water to remove any debris.

11. (Reassembly, 2-1/2 – 3” Models) Lubricate the #2 check o-ring, install in the body and close the #4 test cock to hold it in place. Install the plastic retainer by inserting one end into the body groove and then sliding your hand around the face of the retainer, pushing it into the groove as you go. The retainer will “snap” into place when fully seated. Install #1 check and retainer in the same way.

12. (Reassembly, 4 – 6” Models) 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 as described above in the 2-1/2 – 3”

Models Reassembly section.

13. 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.

#1 CHECK ASSEMBLY

#1 RETAINER

#2 CHECK ASSEMBLY

FIGURE 1

Troubleshooting

PROBLEM

1. LEAKING CHECK VALVES

2. LOW OR NO FLOW

FIGURE 2

#2 PLATE RETAINER (4” & 6”)

(PLASTIC RETAINER MODELS 21/2” & 3”)

FIGURE 3

POSSIBLE CAUSES

1. Debris on seat or seal ring

2. Damaged seat area

3. Damaged seat o-ring

CORRECTIVE ACTION

1. Clean seat area

2. Replace check assembly

2. Replace seat o-ring

4. Damaged bolt o-ring (s) on check retainer 4.

Replace o-ring (s)

1. Device installed backwards

2. Gate valves not fully open

3. Low supply pressure

1. Verify flow direction arrow

2. Turn handles counterclockwise

3. Attach pressure gauge to test cock #1 and verify pressure a

®

company

WILKINS, a ZURN Company

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

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Performance Characteristics

15

0 6.3

12.6

MODEL 350XL 2 1/2", 3" & 4" (STANDARD & METRIC)

18.9

FLOW RATES (l/s)

25.2

31.5

37.8

See spec sheet BF-450XL-212&3

for flow curves

44.1

50.4

104

3" (80mm)

2-1/2" (65mm)

4" (100mm)

10 69

5 35

0

0 100

15

0.0

10

5

0

0

15

0.0

10

5

0

0

15

0.0

10

25.2

400

200 300 400

FLOW RATES (GPM)

500

MODEL 350XL 6" & 8" (STANDARD & METRIC)

50.4

FLOW RATES (l/s)

75.6

100.8

600 700 800

0

6" (150mm)

126.0

8" (200mm)

151.2

104

69

35

63.0

800 1200

FLOW RATES (GPM)

1600

MODEL 350XL 10" & 12" (STANDARD & METRIC)

FLOW RATES (l/s)

126.0

189.0

10" (250mm)

2000

1000

63.1

2000

FLOW RATES (GPM)

MODEL 350AXL 4" & 6" (STANDARD & METRIC)

FLOW RATES (l/s)

126.2

3000

189.3

4" (100mm)

6" (150mm)

2400

0

12" (300mm)

252.0

104

69

35

4000

0

252.4

104

69

5 35

0

0 400 800

FLOW RATES (GPM)

⃟ Rated Flow (established by approval agencies)

1200 1600

0

Proper performance is dependent upon licensed, qualified personnel performing regular, periodic 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.

IS350XL&450XL (REV. 9/09)

WILKINS, a ZURN Company

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

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