11
MAINTENANCE MANUAL MODELS 825Y, 825YA, 825, 825D, 825YD & 826YD
Service Procedure 825Y and YA (
3
/
4
–2")
2. Check Valve Seat Replacement Model 825Y
(
3
/
4
–2") (See Figure No. 11)
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
install new, or turn used disc over if new seat disc is not
available.
NOTE: The seat 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 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 Valve Reassembly Model 825Y (
3
/
4
–2")
(See Figure No. 11)
a.
Position the disc in the cleaned holder and retain with disc
washer and screw. CAUTION: DO NOT OVERTIGHTEN
SCREW, SECURE WITH APPROXIMATELY 12 INCH-LBS.
b.
Position the spring around the centering ring of the disc
holder and reinsert the disc holder assembly into the check
body.
NOTE: Ensure the heavy check spring is installed in the No. 1
check valve or the valve will not operate properly and a con-
tinuous discharge may occur.
c.
Apply a thin coating of FDA approved lubricant on the o-ring
in the cap and thread cap onto the check valve body using
the appropriate sized wrench.
1. Check Valve Inspection/Repair Model 825Y
(¾
–2") (See Figure No. 11)
a.
Close inlet and outlet shut-off valves. Bleed residual pres-
sure by opening first the #4 test cock, then the #3 and #2
test cocks. See Figure No. 7 for test cock locations
b. Unscrew Cap using appropriate size wrench.
CAUTION: Cap is spring loaded. First check spring force on
3
/
4
" to 1
1
/
2
" is 10 lb. First check spring force on 1
1
/
2
" to 2" is
28 lb. Retain cap with appropriate amount of hand force to
avoid injury. Second check spring force is approximately
1
/
4
of
the first check spring.
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 an appro-
priate size reamer or a thin blade knife.
3
/
4
–1
1
/
4
" cap —
5
/
8
"
(.6250) reamer 1
1
/
2
–2" cap—
7
/
8
" (.8750) reamer.
e.
Check disc holder and stem movement in the guide to
ensure they move freely. Debris can inhibit proper move-
ment.
