Installation Guide
Testing Procedures
2
ZURN WILKINS
1747 Commerce Way, Paso Robles, CA 93446 Phone:855-663-9876 Fax:805-238-5766
MODEL 975XL2 REDUCED PRESSURE PRINCIPLE
ASSEMBLY
Equipment Required: Differential pressure gauge test kit.
975XL2 TEST NO. 1
Purpose:
Test #2 check valve for tightness against reverse ow.
Requirement:
The valve must close tight against reverse ow under all pressure
differentials.
Procedure:
1. Attach the "HIGH" hose to test cock #2 and the "LOW" hose
to test cock #3.
2. Close #2 shut-off valve.
3. Open test cocks #2 and #3.
4. Open by-pass valves "C" and "A" and bleed to atmosphere
until all air is expelled.
5. Close by-pass valve "A". Open by-pass valve "B" and bleed
to atmosphere until all air is expelled. Close by-pass valves
"B" and "C".
6. Attach the "VENT" hose to test cock #4.
7. Slowly open by-pass valves "A" and "C" and keep by-pass
valve "B" closed.
8. Open test cock #4.
9. Indicated pressure differential will drop slightly. If pressure
differential does not continue to decrease, the #2 check valve
is considered tight.
975XL2 TEST NO. 2
Purpose:
Test #1 check valve for tightness and record pressure drop across
#1 check valve.
Requirement:
The static pressure drop across #1 check valve shall be greater than
the relief valve opening point (test #1), and at least 5.0 psid.
Procedure:
1. Close by-pass valve "A"
2. Close test cock #4, and disconnect "VENT" hose from test cock
#4.
3. Open by-pass valves "B" and "C" bleeding to atmosphere,
then close by-pass valve "B" restoring the system to normal
static condition.
4. Observe the pressure differential gauge and note this as the
#1 check valve psid.
975XL2 TEST NO. 3
Purpose:
To test operation of the differential relief valve.
Requirement:
The pressure differential relief valve must operate to maintain the
"ZONE" between the two check valves at least 2 PSID less than
the supply pressure.
Procedure:
1. Close by-pass valve "C" and open by-pass valve "A".
2. Open by-pass valve "B" very slowly until differential gauge
needle starts to drop. Hold the valve at this position and
observe the gauge reading at the moment the rst discharge
is noted from the relief valve. Record this as the opening
differential pressure of the relief valve.
#1 TEST COCK
#2 TEST COCK
#3 TEST COCK
#4 TEST COCK
#1 SHUT-OFF
VALVE
VENT HOSE
LOW SIDE HOSE
HIGH SIDE HOSE
BY-PASS
VALVE "B"
BY-PASS
VALVE "C"
BY-PASS
VALVE "A"
#2 SHUT-OFF VALVE
#1 CHECK VALVE
#2 CHECK VALVE
975 XL2
WILKINS
ZURN
175 PSI
180° F
ASSE 1013
VENT
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