6
Servicing the Relief Valve
Sizes: 2
1
⁄
2
" – 10"
CAUTION
!
Use the clearance recommendations referenced below for servicing
relief valve assemblies according to valve size. Figure 6 shows the
differences between the assemblies by valve size.
1. Remove the relief valve cover bolts. Series 909/LF909-FS is
designed so that when the bolts are loosened by
1
⁄
2
" all the relief
valve spring load is retained by the bottom plug spring module.
Verify this before removing all the bolts.
2. Remove the cover and diaphragm. The relief valve piston
assembly can be lifted straight up and out.
3. Replace the wiper seal and piston O-ring and apply grease to
the O-ring.
4. To replace the relief valve disc, hold the upper guide fin and
unscrew the diaphragm pressure plate. If necessary, lightly tap
the cast webs and the pressure plate to loosen. Replace with
a new disc holder assembly and O-ring. The disc rubber is
molded into the disc holder and supplied as a disc holder
assembly.
5. Inspect the bottom plug and spring assembly. During normal
field service there is no need to remove this assembly other than
inspection. Unscrew the assembly with a large pipe wrench.
CAUTION
!
The spring is retained on the bottom plug and is highly loaded. NO
attempt should be made in the field to disassemble the bottom plug
and spring piston assembly. For replacement, a complete bottom
plug assembly must be obtained from the factory.
For further details contact your technical sales representative.
CLEARANCE REQUIRED FOR SERVICING
Valve Size
Clearance
2
1
⁄
2
" – 3"
11"
4"
14"
6"
16"
8"
21"
10"
21"
Relief Module
Adapter O-ring
Diaphragm
Relief Valve Disc
Relief Valve Piston
Assembly
Piston O-Ring
Seat
O-ring
Sizes
2
1
⁄
2
" – 3"
Diaphragm
Sizes
8", 10"
Relief Valve Assembly
Seat
O-ring
Plug & Spring Piston
Assembly
Adapter O-ring
Diaphragm
Sizes 4", 6"
8"M1, 10"M1
Relief Valve Piston
Assembly
Piston seal
Seat
O-ring
Plug &
Spring Piston
Assembly
Adapter O-ring
Clearance Recommended for Servicing
Clearance
Figure 6.
Relief Valve Assemblies by Valve Size
Relief valve with
integrated flood sensor
Relief Valve
Flood Sensor
Activation Module
Air Gap
Module Cable
