Design And Principle Of Operation - Samson 3277 Mounting And Operating Instructions

Design and principle of operation

1 Design and principle of operation
Type 3277 Pneumatic Actuators with an ef-
fective diaphragm area of 240, 350 or
2
700 cm are primarily mounted to control
valves from the Series 240, 250 and 280.
Type 3277-5 with a die-cast aluminum case
and an effective diaphragm area of
2
120 cm , is mounted to Type 3510 and
Series 240 Control Valves.
The actuator is made up of two diaphragm
cases, a rolling diaphragm and springs.
The lower diaphragm case is permanently
fixed to the yoke which allows the direct at-
tachment of either a pneumatic or electro-
pneumatic positioner or a limit switch.
Actuators with manual override (Fig. 5) ad-
ditionally have a handwheel mounted on
the diaphragm case. The handwheel moves
Assembly, start-up and operation of the device may only be performed by
trained and experienced personnel familiar with this product.
According to these mounting and operating instructions, trained personnel is
referred to individuals who are able to judge the work they are assigned to
and recognize possible hazards due to their specialized training, their know-
ledge and experience as well as their knowledge of the relevant standards.
Any hazards which could be caused by the signal pressure and moving parts
of the actuator are to be prevented by means of appropriate measures.
Proper shipping and appropriate storage are assumed.
2
EB 8311 EN
the actuator stem over a spindle after the
locking mechanism (lock nut) has been
disengaged. In addition, the actuator can
be equipped in a special version with a
mechanically adjustable travel stop.
The signal pressure creates a force at the
diaphragm surface which is balanced by
the springs (6) arranged in the actuator.
The number of springs and their com-
pression determine the bench range (signal
pressure range) while taking the rated travel
into account which is directly proportional
to the signal pressure. A maximum of 30
springs can be installed, partly fitted inside
one another.
The stem connector (16) connects the actua-
tor stem (2) with the plug stem of the control
valve.