Advertisement
Testing Double Check Valve Assemblies
Test Check Valve No. 1
1. Ensure shutoff No. 1 is open, and shutoff No. 2 is closed.
2. Connect the high side hose to test cock No. 3, the low side
to test cock No. 2, and open both test cock No. 2 and test
cock No. 3.
3. Open valve C, then open A to bleed air from the high side.
Close valve A, then open B to bleed low side. Close valve B.
4. Connect the vent hose loosely to test cock No. 1. Open
valve A to vent air from the vent hose. Tighten the vent hose
at test cock No. 1, and open test cock No. 1.
5:. Close shutoff No. 1. Slowly loosen the hose at test cock No.
2 until the differential gauge rises to 2psi and retighten the
hose. If the differential reading does not decrease, record the
check valves as "tight."
Test Check Valve No. 2
1. Move the high side hose to test cock No. 4, the low side
to test cock No. 3, and open both test cock No. 3 and test
cock No. 4. Remove the vent hose from test cock No. 1,
and open shutoff No. 1.
2. Open valve C, then open valve A to bleed air from the high
side. Close valve A, then open valve B to bleed the low side.
Close valve B.
3:. Connect the vent hose loosely to test cock No. 1. Open
valve A to vent air from the vent hose. Tighten the vent hose
at test cock No. 1, and open test cock No. 1.
4. Close shutoff No. 1, then slowly loosen the hose at test
cock No. 3 until the differential gauge rises to 2psi and
retighten the hose. If the differential reading does not
decrease, record the check as tight. Remove all the hoses
and restore the valve to original working condition.
WARNING
!
The assembly will fail both the first and second check valve tests
above, if shutoff No. 2 leaks excessively. To test for a leaky No.
2 shutoff, use the following procedure.
Test for Leaky No. 2 shutoff
1. Connect the high side to test cock No. 1, the low side to test
cock No. 4. Open test cock No. 1 and test cock No. 4. Close
shutoffs No. 1 and No. 2.
2. Close valve C. Open valve A, next open valve B 1/2 turn, then
loosen the hose at test cock No. 4 to remove air. Retighten
the hose.
3. If the differential gauge rises above 0 (zero), there is excessive
leakage at shutoff No. 2. The shutoff must be replaced to test
the assembly.
Ball Type Test Valves
A
High Hose
(Yellow)
Low Hose
(White or Red)
Test Cock
Test Cock
No. 1
No. 2
C
B
Needle
Valve
Vent Hose
(Blue)
Test Cock
Test Cock
No.3
No.4
5
Advertisement
