YARWAY MODEL 20 PNEUMATIC DIAPHRAGM ACTUATOR
INSTALLATION, OPERATION AND MAINTENANCE INSTRUCTIONS
UNPACKING
The Yarway pneumatic diaphragm actuators
are mostly delivered in combination with
Desuperheaters for use on low-, medium- and
high pressure steam applications and packed
with the greatest care in wooden boxes or
cartons for protection during handling and
transit to site. If it is found, however, that
damage has occurred during shipment, then
this should be reported immediately to your
forwarder or Yarway representative.
Particular care should be taking when
removing the pneumatic diaphragm actuators
(including Desuperheaters) from the packing
and your special attention is required to
check carefully that no damage has occurred
to the actuators, accessories as: pneumatic
positioner, electric/pneumatic positioner,
position transmitter, air filter regulator, booster
relay, lock-in relay, limit switches, solenoid
valves and the standard piping with stainless
steel pipe and fittings.
Warning: the hoisting lug is for the actuator
only, NOT for a total assembly!
VCIOM-03327-EN 16/10
Before installation these instructions must be fully read and understood
PRINCIPLE OF OPERATION
In a direct acting diaphragm actuator,
increasing loading pressure moves the actuator
stem downward, compressing the spring. When
the loading pressure is decreased, the spring
moves the actuator stem upward.
In the event of failure of the loading pressure
or the operating medium pressure to the
controller, the actuator stem moves to the
upward position.
Warning: be certain that the diaphragm casing
pressure does not exceed the limits listed in
the specification table (see table 1).
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