3
Table 2. Valve Cover Bolt Torque
Valve Size Torque (ft-lbs)
2”-2.5” 1/2" 75
3” 7/16" 50
4” 1/2" 75
6” 5/8" 150
8” 5/8" 150
10” 7/8" 400
12”-20” 7/8” 400
24” 1” 500
30” 1 1/8” 600
36” 1 1/4” 900
42” 1 1/2" 1,400
48” 1 1/2” 1,400
TROUBLESHOOTING
Several problems and solutions are presented
below to assist you in troubleshooting the valve
assembly in an efficient manner.
Leakage at Bottom Actuator: Remove line
pressure and exercise actuator. If leak persists,
replace seals in actuator; see the Backflow
Actuator Seal Replacement Procedure on page
4.
Leakage at Cover or Flanges: Tighten bolts,
replace cover seal.
Valve Leaks when Closed: Inspect disc for
damage and replace. Inspect metal seating
surface and clean if necessary.
Valve Does not Open: Check for obstruction in
valve or pipeline; see Disassembly procedure on
page 4. Operating pressure may be less than
cracking pressure. If less than 0.5 psig, review
application with factory.
Valve Slams Closed: Add additional accelerator.
DISASSEMBLY
The valve can be disassembled without removing
it from the pipeline. Or for convenience, the valve
can be removed from the line. All work on the
valve should be performed by a skilled mechanic
with proper tools and a power hoist for larger
valves. Disassembly may be required to inspect
the disc for wear or the valve for deposits.
1. Relieve pressure and drain the pipeline. Refer
to Figure 2 on page 2. Remove the cover bolts
(5) on the top cover.
2. Pry cover (2) loose and lift off valve body. 14”
and larger valves have tapped holes in cover
for lifting eyes.
3. Remove disc (3) and inspect for cracks, tears
or damage in rubber sealing surface.
4. Clean and inspect parts. Replace worn parts
as necessary and lubricate parts with FDA
grease such as Lubriko #CW-606.
RE-ASSEMBLY
All parts must be cleaned. Gasket surfaces should
be cleaned with a stiff wire brush in the direction of
the serrations or machine marks. Worn parts,
gaskets and seals should be replaced during
reassembly.
1. Lay disc (3) over seat with beaded seating
surface directed down.
2. Lay disc accelerator (13) over center of disc
hinge. If two accelerators are provided, stack
them over the center of the disc hinge.
3. Lay cover gasket (4) and cover (2) over bolt
holes and disc hinge. Where o-ring seal is
provided, place o-ring into body groove. O-ring
may be held in place with compatible grease
for re-assembly. Food grade grease should be
used for standard Buna-N o-rings. For EPDM
o-rings, silicone grease should be used.
4. Insert lubricated bolts (5) noting that the bolts in
the hinge area are longer than the other cover
bolts.
5. Cover bolts should be tightened to the following
specifications during assembly.
WARNING
The line must be drained before removing
the cover or pressure may be released
causing bodily harm.
(8 Seiten)
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