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EB 8052-E EN
3-5
Design and principle of operation
Actuator stem retracts (FE)
When the signal pressure is reduced or the
air supply fails, the springs (A10) move the
actuator stem (A7) upward and open the
valve. The valve closes when the signal pres-
sure is increased enough to overcome the
force exerted by the springs.
The actuator's direction of action can be re-
versed, if required. Refer to the mounting
and operating instructions of the pneumatic
actuator:
u
EB 8310-X for Type 3271 and Type 3277
3.2 Versions
Actuators
In these instructions, the preferable combina-
tion with a SAMSON Type 3271 or
Type 3277 Pneumatic Actuator is described.
The pneumatic actuator (with or without
handwheel) can be replaced by another
pneumatic actuator in a different size, but
with the same travel.
Î
Observe the maximum permissible actu-
ator force.
If the travel range of the actuator is larger
than the travel range of the valve, the spring
assembly in the actuator must be preloaded
so that the travel ranges match. See associ
-
ated actuator documentation.
The basic pneumatic actuator can be re
-
placed by a pneumatic actuator with addi-
tional handwheel or by an electric actuator
(see Information Sheet
u
3.3 Accessories
Transport eyelet/swivel hoist
Sprues fitted with a female thread on the
valve body allow the attachment of transport
eyelets or swivel hoists used for lifting the
valve. They are available as accessories:
Accessories
Working load
limit
Material no.
Transport eyelet
M16x20
2000 kg
8325-1254
Swivel hoist
M16x20
1120 kg
8442-1017
Transport eyelet
M20x30
2000 kg
100063433
Lifting tackle
A special lifting tool is available to lift the
valve without actuator (
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3.4 Additional fittings
Strainers
We recommend installing a SAMSON
strainer upstream of the valve. It prevents sol-
id particles in the process medium from
damaging the valve.
Bypass and shut-off valves
We recommend installing a shut-off valve
both upstream of the strainer and down
-
stream of the valve and installing a bypass
Tip
Note
Summary of Contents for 3251-E
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