Watts 994-FS Serie Manual De Instalación & Mantenimiento página 9

Troubleshooting
PROBLEM
Assembly discharges from differential relief valve during
no flow condition
Assembly discharges from differential relief valve during
a flow condition
Differential pressure relief valve does not open during test
Pressure relief valve does not close
CAUSE
Fouled first check
Fluctuating inlet pressure
Outlet pressure higher than inlet pressure and leak in
check valve #2
Leak through diaphragm or around flange bolt holes of
relief valve
Pressure relief valve does not close
Check valve #1 wedged open
O-ring displaced from groove in check #1
Pressure relief valve does not close
Fluctuating line pressure
Differential pressure across check valve #1 stays above
2.0 psi due to leaking outlet gate valve
Weak or broken relief valve spring
Shutoff seat tube bound in body
Plugged hydraulic hose
Debris on sealing surface
Plugged hydraulic hose
Damaged seat or rubber shutoff disc
Ruptured diaphragm
Wrinkled or improperly installed diaphragm
SOLUTION
Disassemble and clean check valve #1
Control supply line water pressure
Install a soft-seated, spring-loaded check valve upstream
of the assembly
Disassemble and clean check valve #2 and identify cause
of backpressure
Service relief valve
See problem 'Pressure relief valve does not close'
Disassemble and clean check valve #1
Disassemble and replace
See problem 'Pressure relief valve does not close'
Install pressure sustaining check upstream of backflow
Repair shutoff valves
Disassemble and replace relief valve spring
Disassemble and repair
Disassemble and repair
Remove relief valve and clean
Disassemble and clean
Remove relief valve assembly and replace
Disassemble and replace diaphragm
Disassemble and properly position diaphragm
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