A I R V A L V E / C E N T E R S E C T I O N D I S A S S E M B L Y
The air valve assembly consists of both the air valve
body and piston and the center block. The unique
design of the air valve relies on differential pressure to
effect the diaphragm shift. It is reliable and simple to
maintain. The bushing in the center block, along with
the diaphragm shaft, provides the “trigger” to tell the
air valve to shift. The following procedure will ensure
that the air valve on your Wilden pump will provide
long-lasting trouble-free service.
Air Valve Body And Piston
Assembly And Disassembly:
The air valve body and piston can be disconnected
from the pump by removing the four socket head cap
screws which attach it to the center block. The piston
in the air valve is aluminum with a dark gray anodized
coating. The piston should move freely and the ports
in the piston should line up with the ports on the face
of the air valve body (see fi gure A). The piston should
also appear to be a dull, dark gray in color. If the piston
appears to be a shiny aluminum color, the air valve is
probably worn beyond working tolerance and should
be replaced.
If the piston does not move freely in the air valve,
the entire air valve should be immersed in a
cleaning solution.
[
NOTE
: Do not force the piston by inserting a metal
object.] This soaking should remove any accumulation
of sludge and grit which is preventing the air valve
piston from moving freely. Also, remove and clean the
air valve screen. If the air valve piston does not move
freely after the above cleaning, the air valve should be
disassembled as follows: remove the snap ring from
the top end of the air valve cylinder and apply an air jet
to the 3/16-inch hole on the opposite end of the air valve
face (see fi gure B).
CAUTION
: The air valve end cap may
come out with considerable force. Hand protection such
as a padded glove or rag should be used to capture the
end cap.
Figure A
Figure B
WIL-11140-E-03
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WILDEN PUMP & ENGINEERING, LLC
