5
Test No.1
Purpose:
To test check valve No. 2 for tightness against reverse
flow.
Requirements:
Valve must be tight against reverse flow under
all pressure differentials. Slowly open the ‘high’ valve A and the
‘vent’ valve C, and keep the ‘low’ valve B closed. Open test
cock No. 4. Indicated pressure differential is expected to de-
crease lightly. If pressure differential continues to decrease (until
the vent opens) check valve No. 2 is reported as ‘leaking.’
Test No. 2
Purpose:
To test shutoff No. 2 for tightness.
Requirements:
After passing test No. 1, continue to Test No. 2
by closing test cock No. 2. The indicated pressure differential is
expected to decrease slightly. If pressure differential continues
to decrease (approach 0 (zero)), shutoff No. 2 is reported to
be ‘leaking.’
Test No. 3
Purpose:
To test check Valve No. 1 for tightness.
Requirements:
Valve must be tight against the reverse flow under
all pressure differentials. Close ‘high’ valve A and open test cock
No. 2. Close test cock No. 4. Disconnect the vent hose at test
cock No. 4. Open valves B and C, bleeding to atmosphere.
Then closing valve B restores the system to a normal static
condition. Observe the pressure differential gauge. If there is a
decrease in the indicated value, check valve No. 1 is reported as
‘leaking.’
Test No. 4
Purpose:
To test operation of pressure differential relief valve.
Requirements:
The pressure differential relief valve must operate
to maintain the ‘zone’ between the two check valves at least 2 psi
less than the supply pressure. Close ‘vent’ valve C. Open ‘high’
valve A. Open the ‘low’ valve B very slowly until the differential
gauge needle starts to drop. Hold the valve at this position and
observe the gauge reading when the first discharge is noted from
the relief valve. Record this as the opening differential pressure of
the relief valve.
Testing Reduced Pressure Zone Assemblies
Ball Type Test Valves
A
C
B
Needle
Valve
High Hose
(Yellow)
Low Hose
(White or Red)
Vent Hose
(Blue)
Test Cock Test Cock Test Cock Test Cock
No. 1
No. 2
No. 3
No. 4
Servicing the Relief Valve
WARNING
!
Before servicing the relief valve, shut down the water system
by closing both the inlet and outlet shutoff valves and relieving
pressure within the assembly by opening the test cocks No. 2,
No. 3, and No. 4.
DO NOT REMOVE SPIDER BUSHING FOR SERVICING
1. Disconnect the hose from the bottom cover plate to the
relief valve.
2. An O-ring seals the relief valve body to the main housing.
Avoid tightening the connection beyond firm hand tightening.
Loosen the relief valve by hand to remove it, then unscrew the
relief valve from the housing.
3. Remove the cover plate of the relief valve by detaching the
four connecting screws.
4. Remove the rubber diaphragm from the relief valve. Notice
how the diaphragm is configured to reinstall it in the same
manner. The hard rubber tab in the diaphragm fits into a similar
socket in the head of the piston. (See Figure A.)
Figure A
Figure B
5. Hold the relief valve in both hands with the threaded end
up and both thumbs on the head of the piston. Push up on
the piston until the piston shaft with the attached E-clip is
exposed. Remove the E-clip. (See Figure B.)
6. Remove the piston and spring from the relief valve housing and
thoroughly clean all parts including the diaphragm. Inspect all
rubber parts and replace any that are damaged.
7. Reverse the order of these steps to reassemble the parts
and housing.
NOTICE
The differential gauge needle MUST drop slowly. Close test cocks
No. 2 and No. 3. Use the vent hose to relieve pressure from the test
kit by opening valves A, B, and C. Remove all test equipment then
open shutoff No. 2.
