INST2018_Model350_65-250 Rev. 11/18
ZURN.COM.AU
ZURN WILKINS BACKFLOW
Double Check Valve Assembly
INSTALLATION & MAINTENANCE
MODEL 350 65-250mm
TESTING PROCEDURES
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.
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.
EQUIPMENT REQUIRED: Differential pressure gauge test kit.
VENT HOSE
LOW SIDE HOSE
HIGH SIDE HOSE
LOW SIDE BLEED
NEEDLE VALVE
#1 TEST COCK
#4 TEST COCK
#3 TEST COCK
#2 TEST COCK
#2 SHUT-OFF
VALVE
#1 SHUT-OFF
VALVE
HIGH SIDE BLEED
NEEDLE VALVE
