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MAINTENANCE MANUAL MODELS 825Y, 825YA, 825, 825D, 825YD & 826YD
Service Procedures
Relief Valve 825, 825D and 825YD (2
1
/
2
–10")
1a. Relief Valve Disassembly Non-Modular Type
Relief Valve Models 825 and 825D
(See Figures No. 13 and 17)
1. Remove copper tubing from relief valve body.
2. Un-thread the relief valve completely from the check valve body,
leaving the seat ring in the check valve body.
NOTE: If the seat ring is removed with the relief valve, the seat
ring must be un-threaded from the relief valve diaphragm plate,
being careful not to damage the seat ring threads and seating
surface.
3. Remove cover bolts and nuts, diaphragm cover and spacer from
the relief valve assembly.
4. Turn the relief valve upside down, un-thread screw (Item 35)
using a
9
/
16
hex socket, and remove diaphragm assembly, spring
button and spring.
5. Un-thread screw (Item 48) and remove diaphragm washer and
diaphragm from diaphragm button.
6. Push main stem out of bottom of relief valve body.
7. Remove o-ring from body.
2a. Relief Valve Reassembly Non-Modular Type
Relief Valve Model 825 and 825D
(See Figure No. 17)
1. Assemble washer, outer diaphragm, spacer, diaphragm button,
inner diaphragm and washer by securing with capscrews to form
diaphragm assembly. When installing diaphragms, make sure
side of diaphragm marked “button side” (fabric side) is toward
diaphragm button and that diaphragm is not pinched.
2. Lubricate main stem o-ring with FDA approved lubricant. Place
seat disc on main stem and place disc washer on seat disc.
3. Slide main stem bolt through main stem assembly and place
inside relief valve body cavity with main stem bolt protruding.
4. Position spring over bolt and fit diaphragm assembly over spring.
Compress diaphragm assembly into spring until main stem bolt
threads into diaphragm assembly. Secure using a torque wrench.
DO NOT TIGHTEN MAIN STEM BOLT BEYOND 15 INCH-LBS.
OR DISTORTION OF THE MAIN STEM (ITEM 30) WILL OCCUR.
5. Thread seat ring into main valve body and thread relief valve into
seat ring.
6. Reconnect copper tubing to relief valve.
7. Slowly open inlet shut-off valve and bleed air by opening first test
cock #4, then test cocks #3, and #2 and all air bleeds.
8. Slowly open outlet shut-off valve and return the valve to service.
9. Test the assembly to ensure it is operating properly.
3a. Relief Valve Seat Disc Replacement Modular
Type Relief Valve Model 825YD
(See Figure No. 18)
1. Disconnect sensing tubing. Remove relief valve cover (Item 21)
by loosening cover bolts (Item 25) and remove the outer dia-
phragm (Item 26).
2. Grasp the relief valve button (Item 24) with one hand. Insert
fingers into the rectangular relief valve port on the bottom of the
relief valve and apply force to the seat disc. Pull the relief valve
module straight out from the body. DO NOT TWIST.
3. Place the relief valve module on a flat surface. Holding the main
stem with one hand, loosen and remove the lower guide (Item
35) and disc washer (Item 33). Remove the rubber seat disc (Item
32) and turn over or replace as required. Inspect all parts and
clean using clean water. Refer to section 5a on replacing relief
valve diaphragms if this procedure is necessary.
4. Replace the disc washer and lower guide and tighten. Lubricate
the o-ring (Item 31a), with FDA avpproved lubricant. Insert the
relief valve module into relief valve body, using your fingers to
help guide the lower guide into the bushing (Item 36a) on the
relief valve seat ring. Push the module straight in. DO NOT
TWIST.
5. If the relief valve module does not have a center label piece cov-
ering the screw (Item 48), inspect the screw for burrs. If a burr is
visible, remove or cover burr with a piece of flexible tape. This will
protect the surface of the diaphragm.
6. Replace the diaphragm, placing the fabric side against the button.
Work the rolled edge into the space between the module and the
body making sure it is not pinched or buckled.
7. Replace the cover, tighten the cover bolts, and reconnect the
sensing tubing. Return to service and test the assembly to ensure
proper operation.
