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KEYSTONE SWING CHECK VALVE
Figures 809 to 815 installation and maintenance instructions
FIGURE 2.
Components
FIGURE 3.
Seat types
Item no. Part name
1Body
2Disc
3Stem
4Spring
5O-ring seat (not shown)
6Washer
7Washer
8Washer
9Washer
10 Pipe plug
11 Not shown
Seat Replacement Procedures
Identify the type of seat. See Figure 3 for
drawings of the different seat types.
If the valve has an integral O-ring seat, proceed
to Step 1 below. If the valve has replaceable
O-ring or replaceable metal-to-metal seat,
it is obsolete and no replacement seats are
available. A new valve must be purchased. If the
valve has an integral metal-to-metal seat, the
seat is not repairable because it is machined
directly into the body.
1. Cut the O-ring and pry it out of the dovetail
groove. Take care not to damage dovetail
groove. Throw the old seat away.
2. Lubricate the new O-ring with silicone oil.
3. Place the O-ring in the dovetail groove that
is machined into the body.
4. Verify that the O-ring is not twisted or
pinched.
Figure 809 & 810
integral O-ring seat
Figure 810
replaceable O-ring
seat (obsolete)
Figure 810
replaceable metal to
metal seat (obsolete)
Figure 809 & 810
integral hard seat
Symptom Possible Cause Resolution
Valve slamming 1. The valve usually slams as a result of air trapped
downstream of the valve.
Bleed the air traps.
Valve bouncing at closure 1. The disc may bounce due to column separation
upstream of the valve
Add a vacuum breaker.
Valve leaking 1. Check for foreign material caught in the seat.
2. Damaged seat seal.
Remove the material from the seat area.
Replace seat seal.
Maintenance Procedure
The maintenance requirements of the
Figure 809 to 815 are minimal. No
lubrication is required. In the event a part
requires replacement, following are the
valve disassembly/-assembly instructions
referencing Figure 2.
1. Place the bottom of the valve in a vise.
Protect the valve faces by using wooden (or
other suitable material) spacers between
vise faces and valve faces.
2. Remove the pipe plug (10).
3. While holding the disc (2) in place, pull the
stem (3) out of the body (1).
4. Remove the washer (6 to 9 depending on the
valve) and spring (4).
5. Set the disc aside.
6. If seat (11) replacement is required, proceed
to seat replacement procedure.
7. Replace worn parts.
8. Place the washers (6 to 9), spring (4) and
disc (2) into the valve body as shown in the
SMO drawing. Run the stem into the body
through the first set of washers, first arm of
disc, spring, second arm of disc and last set
of washers.
9. Seal the pipe plug threads with PTFE tape
and install the plug.
10. Push the disc completely open several times
by hand to ensure the disc is not binding and
to verify proper seating.
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