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MAINTENANCE MANUAL MODELS 825Y, 825YA, 825, 825D, 825YD & 826YD
Service Procedures 825, 825D and 825YD (4–10")
b.
Inspect seat disc for wear or damage. Replace with new
seat disc or turn used disc over if new disc is not available.
NOTE: The discs are symmetrical. It is usually possible to turn
the disc over and obtain an effective seal.
c.
If the seat disc has been severely cut along the seat disc
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. A
seat disc damaged in this manner should be replaced and
not turned over for reuse.
d.
Remove disc holder from stem.
NOTE: On older Model 825 valves, the disc holder is sealed
to the stem with a sealant. If the seal is broken, the stem
and holder must be cleaned and new sealant applied. Newer
valves, Models 825D and 825YD use an o-ring so a sealant is
not required.
3. Spring Removal (Sizes 4–10")
(See Figures No. 15 & 16)
CAUTION: TO AVOID POSSIBLE INJURY, DO NOT ATTEMPT
TO REMOVE SPRING TENSION WITHOUT THE USE OF
THE SPRING REMOVAL TOOL SHOWN IN FIGURE NO.
20 ON PAGE 30. ON OLDER MODEL 825 VALVES, IT IS
NECESSARY TO REMOVE THE SPRING BEFORE THE
RUBBER SEAT DISC CAN BE REMOVED.
a.
Leave check assembly in body.
b.
Install long studs in body 180 degrees apart.
c.
Place spring removal tool over stud and retain with nuts.
(See Figure No. 20 for dimensions.)
1. Check Valve Disassembly (Sizes 4–10")
(See Figures No. 15 & 16)
a.
Slowly close outlet gate valve then slowly close inlet gate
valve. Bleed residual pressure by opening first the #4 test
cock, then #3, and #2 test cocks. See Figure No. 8 for test
cock locations.
b.
Remove cover bolts and cover. Unscrew bolts uniformly to
avoid binding of the cover. The spring will push the cover
approximately
1
/
2
inch off the top of the valve body.
2. Seat Disc Removal (Sizes 4–10')
CAUTION: The newer model 825 cast iron units have
threaded disc holders with four (4) cast lugs, (6 lugs on 10"
assemblies),
1
/
2
" high located on back side, outside the spring
diameter. If the Model 825 you are servicing does not have
these lugs, SPRING TENSION MUST BE RELEASED BY
USING THE SPRING REMOVAL TOOL BEFORE FURTHER
DISASSEMBLY. DO NOT ATTEMPT TO REMOVE SPRING
TENSION ON OLDER MODEL 825s WITHOUT THE USE
OF THIS TOOL. SEE SPRING REMOVAL INSTRUCTIONS.
Newer Models 825, 825D and 825YD assemblies have the
disc holder threaded on the stem. Therefore, the seat disc can
be removed without releasing spring tension on these newer
models.
a.
Un-thread retaining nut from stem and remove disc washer
and seat disc.
