User Guide

Check Differential Across 2 to 3 psid Leak in #1 or #2 check valve
#1 Check Valve 6 to 8 psid and steady Malfunctioning pressure relief valve
2 to 7 psid and fl uctuating Inlet pressure fl uctuating
Symptom #1 Reading: Problem:
Troubleshooting Guide
Check Differential Across 2 to 3 psid #1 check valve held open
#1 Check Valve 6 to 8 psid and steady Malfunctioning pressure relief valve
Symptom #2 Reading: Problem:
A) Close Gate Valve #2 If discharge stops Leak in #2 check valve
If discharge does not stop Go to “B”
B) Open #4 test cock to produce a fl ow If discharge stops Leak in #1 check valve
greater than differential relief valve If discharge does not stop Malfunctioning pressure relief valve
discharge
With Differential Pressure Gauge
Symptom #1 and #2 Result: Problem:
Without Differential Pressure Gauge
Symptom #1 Cause: Solution:
Symptom #2 Cause: Solution:
Intermittent discharge from relief
valve during NO FLOW conditions.
With the symptom, the pressure drop
across the #1 check valve would be
varying from about 2 to 7 psid
A. Inlet line pressure variations
causing relief valve to discharge
B. Pressure surges (water hammer) causing
relief valve to discharge as pressure wave
passes through the zone
Eliminate or reduce pressure variations
by installing a soft seated, spring loaded
check on upstream side of device
Eliminate or reduce pressure surges
Continuous discharge from relief valve
during NO FLOW conditions (Discharge
stops with water fl ow)
With this symptom, the pressure drop
across the #1 check valve would be
2 to 3 psid. If a fl ow of water (more
than discharge) is created through
the valve, the pressure drop should
increase to approximately 7 PSI
A. Debris fouling #1 check valve
B. Outlet pressure higher than
inlet pressure and debris
fouling #2 check valve
C. Spring stem not moving freely
D. Damaged seat or seat disc
E. Leakage at seal under the seat ring
F. Large diaphragm damaged and leaking.
Inspect and clean
Inspect and clean
Inspect for dirt or other foreign material
Inspect and replace
Inspect and replace seal
Inspect and replace if required
Symptom #3 Cause: Solution:
Continuous discharge from relief valve
during FLOW and NO FLOW conditions
With this symptom, the pressure drop
across the #1 check valve would be
7 psid or more at all times
A. Seat disc dislodged from cavity in
the main stem (this can be caused by
pressure surges during initial fi lling of
system lines)
B. Debris fouling the relief valve seat
C. Debris blocking the relief valve
sensing passage
D. Dirt or scale jamming main stem
E. Leakage at main stem, small
diaphragm damaged and leaking.
Reposition disc in main stem cavity.
Repressurize system slowly
Inspect and clean
Inspect and clean
Inspect and clean, or replace
Inspect and clean, or replace
4
MAINTENANCE MANUAL MODELS 860 & 880V 2
1
/2" – 10"
IOM-F-860_880V.indd 4 7/11/08 10:45:27 AM