Val-Matic 14 and Larger Wafer and Lug Style Dual Disc Check Valve - Manual (Page 6)

MAINTENANCE
Dual Disc
®
Check Valves require no scheduled
lubrication of maintenance.
INSPECTION: Periodic inspection for leakage can
be performed by listening for leakage noise from the
valve while the pump is shut down. If leakage is
heard, drain the pipeline, remove the valve, and
inspect the seating surfaces for wear or damage. If
the resilient seat is damaged, replace the valve or
return the valve to the factory for refurbishing.
TROUBLESHOOTING
Several problems and solutions are presented below
to assist you in trouble shooting the valve assembly
in an efficient manner.
• Valve Chatters or Vibrates: Verify that velocity is
at least 4 feet per second (consult the factory for
air service). A partially open valve will wear
prematurely. Verify that there are three diameters
of straight pipe upstream.
• Valve Leakage: Check gaskets and flange bolt
torque for flange leakage. Drain line, remove
valve, and inspect seating surfaces.
• Valve Does Not Pass Flow: Check flow arrow
direction on valve body. Verify that downstream
isolation valve is open and there is no line
blockage downstream.
• Valve Slams: Remove valve and inspect spring.
Heavier springs can be furnished for severe high-
head applications. Consult factory if the valve is
installed in a vertical pipe with the flow downward.
DISASSEMBLY
The valve should be removed from the pipeline for
disassembly. All work on the valve should be
performed by a skilled mechanic with proper tools.
Refer to Figure 2.
5
WARNING: The line must be drained before
removing the valve or pressure
may be released causing injury.
1. Remove the valve from the pipeline. 10” and
larger valves have threaded holes for insertion of
an eye bolt. Lay valve on flat surface or bench
with the flow arrow facing upwards.
2. Remove the threaded pin retainers (8) and the
rubber spheres (9). 36” and larger valves have a
thrust collar (4B) which must be removed prior to
driving out the pins.
3. Drive out the pins (4 and 5) with a round bar or
punch while pressing down on the spring (3) to
prevent it from unwinding. Valve 18” and larger
have 2 springs and require extreme care to
prevent rapid uncoiling of the spring during
disassembly. Restrain the spring with boards and
clamps during disassembly.
4. Lift discs (2) from body. Inspect pins and seating
surfaces for wear. The shaft diameter is normally
about 1/16” smaller in diameter than the hole in
the disc lugs. Some minor dents and discoloration
are normal. Wear areas in the resilient seat will
cause leakage and require valve replacement or
refurbishing at the factory.
5. Remove spring (3) and check for wear or cracks.
6. Remove bearings (6) and inspect for wear.
REASSEMBLY
All parts must be clean and the 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 body on flat surface with arrow facing
upwards. Carefully place the two discs with the
machined sealing surfaces down on the body
sealing surface. Align the disc lugs with the pin
holes in the body.
2. Insert the disc hinge pin into the hole on one side
of the body, but not through the disc lugs. Install a
thrust bearing (6) between the inside diameter of
the body and the disc lug. Push the disc hinge pin
further to engage the first disc lug.
3. Install the second thrust bearing (6) between the
first and second disc lugs and push the pin further
to engage the second disc lug.
4. While holding the torsion spring (3) with one of the
ends facing you, wind the rear tab 180 degrees in
a clockwise direction and then press the spring
between the two sets of disc lugs. Engage the pin
further to retain the spring and the third disc lug.
The legs of the spring should apply a downward
force on the discs.
NOTE: 18” and larger valves have 2 springs and
require extreme care to prevent rapid recoiling of
the springs. Restrain the spring during assembly
with boards and clamps.