7
MAINTENANCE MANUAL MODELS 825Y, 825YA, 825, 825D, 825YD & 826YD
Troubleshooting Procedure
Troubleshooting Guide
With Differential Pressure Gauge
SYMPTOM NO. 1:
CHECK DIFFERENTIAL ACROSS NO. 1 CHECK VALVE
READING
PROBLEM
2 to 3 PSID
Leak in No. 1 or
No. 2 check valve
6 to 8 PSID and steady
Malfunctioning pressure relief valve
2 to 7 PSID fl uctuating
Inlet pressure fl uctuating
With Differential Pressure Gauge
SYMPTOM NO. 2:
CHECK DIFFERENTIAL ACROSS NO. 1 CHECK VALVE
READING
PROBLEM
2 to 3 PSID
Leak in No. 1 or
No. 2 check valve
6 to 8 PSID and steady
Malfunctioning pressure relief valve
Without Differential Pressure Gauge
SYMPTOMS NO. 1 AND NO. 2:
A) Close Gate Valve No. 2
RESULT
PROBLEM
If discharge stops
Leak in No. 2 check valve
If discharge does not stop
Go to "B"
B) Open No. 4 testcock to produce a fl ow greater than
differential relief valve discharge
RESULT
PROBLEM
If discharge stops
Leak in No. 1 check valve
If discharge does not stop
Malfunctioning pressure relief valve
SYMPTOM:
CAUSE:
SOLUTION:
1. Continuous discharge from relief valve during
NO-FLOW condition (discharge stops with water
fl ow).
With this symptom, the pressure drop across the
No. 1 check valve would be 2 to 3 PSID.
If a fl ow of water (more than the discharge) is
created through the valve, the pressure drop
should increase to approximately 7 PSID.
a. Debris fouling No. 1 check valve.
a. Inspect and clean.
b. Outlet pressure higher than inlet pressure and
debris fouling No. 2 check valve.
b. Inspect and clean.
c. Disc holder/stem not moving freely in guide(s).
c. Inspect for dirt or other foreign material.
d. Damaged seat or seat disc.
d. Inspect and replace. Seat disc can
be reversed.
e. Leakage at o-ring on the seat ring or disc holder/
stem (825, 825D, 825YD).
e. Inspect and replace o-ring.
f. Leakage under seat disc due to dirt or damage disc
holder or disc.
f. Inspect and replace or repair.
g. Leakage through diaphragm due to stretched holes
or cut (825 & 835YD).
g. Inspect and replace diaphragm.
2. Intermittent discharge from relief valve during
NO-FLOW condition. With this symptom, the
pressure drop across the No. 1 check valve would
be varying from about 2 to 7 PSID.
a. Inlet line pressure variations causing relief valve
to discharge:
a. Elimate or reduce pressure variations.
b. Pressure surges (water hammer) causing relief
valve to discharge as pressure wave passes
through "ZONE."
b. Eliminate or reduce pressure surges.
3. Continuous discharge from relief valve during
FLOW and NO-FLOW conditions.
With this symptom, the pressure drop across the
No. 1 check valve would be 7 PSID or more at all
times.
a. Seat disc dislodged from cavity in the in the main
stem (this can be caused by pressure surges
during initial fi ling of system lines.)
a. Reposition disc in main stem cavity. Repressurize
system slowly.
b. Debris fouling the relief valve seat.
b. Inspect and clean.
c. Debris fouling the relief valve seat passage.
c. Inspect and clean.
d. Dirt or scaling jamming main stem or spring
button.
d. Inspect and clean or replace.
e. Leakage at main stem or o-ring/diaphram.
e. Inspect and clean or replace o-ring and/or main
stem.
f. Jammed main stem due to excessive torque on
center bolt (825 and 825D).
f. Do not exceed 15 inch-pound torque on main stem
center bolt.
