9
Problem
Cause
Solution
A. Assembly discharges from
Fouled first check
Disassemble and clean No. 1
differential relief valve during
check valve
no flow condition.
Fluctuating inlet pressure
Control supply line water pressure.
Install a spring-loaded soft seated
check valve upstream of the back-
flow prevention assembly.
Outlet pressure higher than inlet
Disassemble, clean #2 check valve
pressure & leak in No. 2 check valve
& identify cause of back pressure
Leak through diaphragm
Service relief valve
Pressure relief valve does not close
See problem D
B. Assembly discharges from
Pressure relief valve does not close
See problem D
differential relief valve during a
flow condition.
C. Differential pressure relief valve
Differential pressure across No. 1
Repair shutoff valves
does not open during test
check valve stays above 2.0 psi
due to leaking outlet gate valve
Weak or broken relief valve spring
Disassemble and replace relief
valve spring
Plugged hydraulic hose
Disassemble and repair
D. Pressure relief valve
Debris on sealing surface
Remove relief valve and clean
does not close
Plugged hydraulic hose
Disassemble and clean
Damaged seat or rubber shutoff disc
Remove relief valve assembly and
replace
Ruptured diaphragm
Disassemble and replace diaphragm
Trouble Shooting Guide
Содержание 995 Series
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