Ames Fire & Waterworks 5000RPDA Reduced Pressure Detector Assemblies - Manual (Page 6)

6
TROUBLESHOOTING GUIDE
SERIES 2000DCA AND 3000DCDC
PROBLEM CAUSE SOLUTION
Check valve fails to hold minimum Debris on seating area eliminate debris
leaking gate valve (this is determined repair or replace
separately during the test procedure)
damaged seat disassemble and replace
damaged clapper plate disassemble and replace
broken spring disassemble and replace
CHECK VALVE DISC COMPRESSION (When Using A Duplex Pressure Gauge)
During the ‘initial test’, both the high and low side gauges may drop at the same rate, in which case the check valve would normally be
assessed as leaking. However, after both gauges have fallen approximately 10 – 15psi or more, the high side gauge fi nally drops and
holds the required 2psi below the low side gauge. Even though both gauges originally fell together, the check valve is holding tight. The
reason for this is that the check valve disc is compressing as a backpressure is created. As the high (upstream) pressure is bled off to
drop the 2psi, the downstream pressure begins to push harder on the backside of the check valve. So as the seat imbeds further into the
elastomer disc, the volume on the backside of the check valve increases. With an increase in volume there is a corresponding decrease in
pressure. So as the high side gauge is lowered, the disc compression causes a lowering on the low side gauge too. Once the disc stops
compressing, then the high side gauge will drop below the low side gauge and the check valve will show as holding tight.
SERIES 4000RP AND 5000RPDA
PROBLEM CAUSE SOLUTION
A. Assembly discharged from Fouled fi rst check Disassemble and clean No.
differential relief valve during 1 check valve
a no-fl ow condition
Fluctuating inlet pressure Control supply line water pressure
Outlet pressure higher than inlet Disassemble clean #2
pressure & leak in No. 2 check valve check valve & identify cause of back
pressure
Leak thru diaphragm or around Service relief valve
fl ange Bolt holes of relief valve (page 8)
Pressure relief valve-does not close See problem D (pg. 6)
B. Assembly discharges from No. 1 check valve Disassemble and clean No. 1
differential relief valve during wedged open check valve
a fl ow condition
O-ring displaced from groove Disassemble and replace
in relief valve
Pressure relief valve - See problem D (pg. 6)
does not close