6
Servicing the Relief Valve
1. The relief valve may be serviced while on or off the backflow
preventer valve.
2.
NOTICE
DO NOT USE A PIPE WRENCH TO REMOVE THE RE LIEF VALVE
ASSEMBLY FROM THE BACKFLOW PREVENTER.
3. Shut down water system.
Relief Valve Disassembly
1. Disconnect the relief valve hose from the elbow in the bottom
flange cover at the swivel hose connection. Do not remove the
el bow.
2. If the valve is to be removed from the backflow preventer for
service, place a screw driver blade or flat bar across the edges
of two of the hex head screws in the bottom flange cover and
turn counter-clock wise to loosen the relief valve assembly. (See
Figure 2 page 4)
3. Remove the four bottom bolts from the bottom of the relief valve
assembly with a
5
⁄
16
” socket or open-end wrench. Remove the
bottom flange cover.
4. Remove the piston assembly & sleeve from the relief valve body
by placing your index fingers through the slots in the side of the
body and pressing down on the top of the disc retainer in the top
of the piston as sem bly. (See Figure
7.)
5. Pull the piston assembly free of the body by grasping the sleeve
and pulling down.
6. Grip the sleeve and the piston assembly by the head of the hex
head bolt. Pull up on the sleeve to extend the diaphragm. Slide
the sleeve (item #26) completely off of the diaphragm and in-
spect the diaphragm for tears, holes or excessive wrinkles. If the
diaphragm is dam aged, or der a new piston/diaphragm assembly.
Relief Valve Reassembly
1. Thoroughly clean all inside surfaces of the relief valve body.
2. Inspect the relief valve body seat surface located at the top edge
of the three discharge slots near the top of the body by rubbing
the end of the index finger around the entire seat surface; access
the seat sur face through the slots or the bottom of the body. The
seat must be free of nicks. If nicks are discovered, remove the
body & install a new relief valve assembly.
3. Position the diaphragm on the piston assembly so that it is fac ing
up as shown in Figure 8.
4. Now fold the top (ribbed) edge of the diaphragm inward, grasp
the sleeve with the
ribbed edge up
and slide the sleeve down
over the piston assembly as shown in Figure 8.
5. While still holding the sleeve, slide it up over the diaphragm
and, using your thumb & index finger, position the bead of the
diaphragm so that it wraps over the outside of the rib on the top
of the sleeve so that the sleeve is held by the diaphragm. Now
place the pis ton as sem bly on a flat, firm surface with diaphragm
facing up as shown in Figure 9.
6. Cup your hand slightly to form an air trap and force the sleeve
down over the piston assembly with a rapid slap (hard) on the
open end of the diaphragm with your cupped hand. The trapped
air in the di a phragm will force the diaphragm between the inside
of the sleeve and the out side of the piston. Ensure that the dia-
phragm is fully seat ed.
If di a phragm is wrinkled, repeat previous
step.
7. Slide the piston assembly and sleeve into the relief valve body
with the hex head bolt entering the flanged end of the body first.
Slide the piston assembly in until the diaphragm lip is smoothly
seated in the ma chined groove in the flanged end of the body.
By running your in dex finger around the outside of the diaphragm
bead, you will ensure it is seated smoothly
item #
part description
Qty.
21
Relief Valve Body
1
22
Rubber Shutoff Disc
1
23
Piston Diaphragm Assembly
1
24
Hex Head Bolt
4
25
Disc Retainer
1
26
Sleeve
1
27
Bottom Bolt
1
28
Bottom Flange (w st. elbow)
1
29
Bottom st. elbow
1
30
O-ring disc
1
PARTS TABLE #2
Figure 6
27
21
22
23
24
25
26
28
29
30
Figure 7
Figure 8
Figure 9
8. Position the bottom flange cover on the bottom of the relief valve
body and secure by hand tightening the four bottom bolts.
9. Now tighten the four bottom bolts to approximately 15 ft.-lbs.
with a
5
/
16
" socket or open-end wrench.
10. Reattach the relief valve hose to the elbow in the bottom flange
cover.
