Samson 3277 Mounting And Operating Instructions page 2

Design and principle of operation
1 Design
operation
The Type 3277 Pneumatic Actuators with an
effective diaphragm area of 240, 350 or
700 cm² 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
120 cm², is mounted to Type 3510 and Se-
ries 240 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 attach-
ment of either a pneumatic or electropneu-
matic positioner or a limit switch.
Actuators with manual override (Fig. 5) ad-
ditionally have a handwheel mounted on the
diaphragm case. The handwheel moves the
4
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
knowledge and experience as well as their knowledge of the relevant
standards.
4
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.
4
Proper shipping and appropriate storage are assumed.
2
EB 8311 EN
and principle
actuator stem over a spindle after the lock-
of
ing mechanism (lock nut) has been disen-
gaged. In addition, the actuator can be
equipped in a special version with a me-
chanically adjustable travel stop.
The signal pressure creates a force at the di-
aphragm surface which is balanced by the
springs (6) arranged in the actuator. The
number of springs and their compression
determine the bench range (signal pressure
range) while taking the rated travel into ac-
count which is directly proportional to the
signal pressure. A maximum of 30 springs
can be installed, partly fitted inside one an-
other.
The stem connector (16) connects the actua-
tor stem (2) with the plug stem of the control
valve.