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VALVE CONSTRUCTION
The standard Figure 939 Sewage Air & Vacuum
Valve has a cast iron body and cover, 316
stainless steel float, plug, seat and internal
mechanism and a rubber seat. Refer to the List
of Materials submitted for the order if non-
standard materials were provided.
Refer to Page 5 for details of construction and
parts location.
The Figure 939 has a 10 to 200 PSI working
pressure range.
The valve has an inlet connection at the bottom
where the valve attaches to the system and a
outlet connection at the top through which air
leaves and enters the valve.
WARNING
Removing the valve from the line or
disassembling the valve while there is pressure
in the valve body may result in injury or damage
to the valve
PREVENTIVE MAINTENANCE
Figure 939 Sewage Air Vacuum Valves require
no scheduled lubrication or adjustment.
A periodic visual inspection should be performed
to ensure the outlet piping is not obstructed and
to verify there is no fluid leakage.
Depending on the nature of the fluid, sewage air
valves may become clogged with sediment or
grease and require periodic cleaning. To
facilitate such cleaning GA Industries air valves
with an
“F” at the end of the Figure Number
(e.g., 939F)
were supplied with “backflushing
attachments.” Refer to the backflushing
instructions on Page 4 of this manual for
additional information.
TESTING
Valve operation can be easily tested. Close the
inlet isolation valve and remove or loosen the
pipe plug nearest the inlet to drain the water
from the valve. The float should drop as the
water leaves the valve. NOTE: A manual valve
can be installed in place of the pipe plug to
facilitate testing (valves are included with
backflushing attachments).
Replace or tighten the pipe plug and slowly open
the inlet isolating valve. After expelling air, the
valve should close and seal tightly.
TROUBLESHOOTING
•
Valve Does Not Close / Fluid Leakage
Verify debris has not collected on the seat
preventing tight closure
Verify rubber seat and/or seating surfaces
are not damaged
Verify float has buoyancy
Verify internal mechanism operates freely
without binding or sticking
Verify the pressure at the valve inlet it at
least 10 PSI
•
Valve Does Not Open
Verify debris in the valve is not
preventing the float from freely falling
when fluid is drained from valve
Verify internal mechanism operates freely
without binding or sticking
DISASSEMBLY
While small valves may be more easily serviced
by removing it from the line, all valves can be
serviced while the body remains connected to
the pipeline. A skilled technician with proper
tools should perform all work. No special tools
are required.
Disassemble the valve only as far as needed to
replace damaged or worn parts.
First ensure there is no pressure within the
valve. Remove the cover bolts (11) and lift off
cover (2) with internal mechanism attached. It
may be necessary to pry the cover off. Be
careful not to damage or lose the O-ring (8)
unless it
’s being replaced.
Using a chain or strap wrench, unscrew the
cage (3) from the cover (2) being careful not to
lose the seat O-ring (10) unless it
’s being
replaced.
Unscrew float ball (12) from float rod (9). It may
be necessary to apply heat as these parts are
secured with Loctite.
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