3
Servicing the First and Second Check Valves
Seat
Seat
O-ring
Disc
Assembly
Spring
Retainer
Caps/
Seat
Cover
Cover O-ring
Retainer
Body
First Check
Second Check
No special tools are required to service the assembly.
1. Remove cover bolts and cover.
2. Remove the retainer from the body bore. The check valve
modules can now be removed from the valve by hand or with
a screwdriver.
3. The check seats are attached to the cage with a bayonet type
locking arrangement. Holding the cage in one hand, push the
seat inward and rotate counterclockwise against the cage.
The seat, spring cage, spring, and disc assembly are now
individual components.
4. Clean and reassemble the disc assembly. Or depending on
its condition, discard or replace with a new assembly from the
repair kit. O-rings should be cleaned or replaced as necessary.
For more information, refer to repair parts price list PL-RP-BPD.
5. Reassemble the check valve modules. Check modules are
installed in the valve body with the seats facing the valve inlet.
The modules must be securely in place before the retainer can
be replaced.
Check Assemblies
Troubleshooting
SYMPTOM
CAUSE
SOLUTION
Check valve fails to hold
1.0 PSID minimum
Debris on check disc sealing surface
Disassemble and clean
Leaking gate valve
Disassemble and clean or repair
Damaged seat disc or seat O-ring
Disassemble and replace
Damaged guide holding check open
Disassemble and clean or replace
Weak or broken spring
Disassemble and replace spring
Chatter during flow conditions
Worn, damaged or defective guide
Disassemble and repair or replace guide
Low flows passing through
mainline valve
Mainline check fouled
Disassemble and clean
Meter strainer plugged
Disassemble and clean
Damaged mainline seat disc or seat
Disassemble and replace
Broken mainline spring
Disassemble and replace
