9
1 . Bypass Check Valve Inspection/Repair Series 805YB
3
⁄
4
" .
a . Close inlet and outlet shutoff valves . Bleed residual pressure by
opening first the #4 test cock, then the #3 and #2 test cocks .
b . Unscrew cap using appropriate size wrench . NOTE: Cap is spring
loaded .
c . Remove the spring and disc holder assembly .
d . Inspect guiding bore of the cap and poppet stem for any buildup of
calcium or other mineral deposits . If this condition exists, it may be
removed with the careful use of a
5
⁄
8
" ( .6250) reamer or a thin blade
knife .
e . Check disc holder and stem movement in the guide to insure they
move freely . Debris can inhibit proper movement .
2 . Check Valve Seat Disc Replacement Series 805YB (
3
⁄
4
") .
a . Hold disc holder assembly in one hand and remove screw and disc
washer .
CAUTION:
The use of pliers or other tools may damage the guiding
surfaces and require unnecessary replacement .
Do not scratch or mark sealing or guiding surfaces .
b . Inspect seat disc for wear or cuts . Remove old seat disc and
replace . Disc may be turned over for temporary repair until a new
disc is available .
c . If the seat disc has been severely cut along the seat ring diameter,
the assembly is being subjected to extremely high back pressure
from thermal water expansion, water hammer or other causes of
excessive water pressure . Seat discs damaged in such a manner
should be replaced and not turned over to be reused .
3 . Check Seat Ring Replacement
a . The seat rings are threaded into the body with an O-ring seal
against the body . Remove only if the sealing edge is damaged .
Using an inside pipe wrench (1-inch IPS size), grip the inside surface
of the seat ring and loosen the part .
b . Unscrew the seat ring/O-ring and discard .
c . Using lubricant supplied with the repair kit, apply a thin coating of
lubricant to the O-ring surface and position the O-ring on the seat
ring .
d . Thread the seat ring/O-ring into the body until the O-ring is com-
pressed and the seat ring contacts the body . DO NOT TORQUE
BEYOND "HAND TIGHT" .
4 . Check Valve Reassembly Series 805YB (
3
⁄
4
") .
a . Position the disc in the cleaned holder and retain with disc washer
and screw .
b . Position the spring around the centering ring of the disc holder
and reinsert the disc holder assembly into the check body .
c . Apply a thin coating of petroleum jelly (food grade) on the O-ring
in the cap and thread cap onto the check valve body using the
appropriate sized wrench .
d . Close the #4, #3, and #2 test cocks and slowly open first the inlet
and then outlet shutoff valves and return the assembly to service .
e . Test the assembly to insure it is operating properly .
MAINTENANCE MANUAL SERIES 850, 856, 870V & 876V 2
1
⁄
2
"- 10" (65 – 250mm)
Service Procedures for Series 805YB —
3
⁄
4
" Bypass