Samson 3248-1, Монтаж и эксплуатация

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1 Design and principle of
operation
The Type 3248 Cryogenic Valve can be
combined with either a Type 3271 or a
Type 3277 Pneumatic Actuator with integral
positioner attachment.
The globe-pattern or angle-pattern valve
body is designed for welding in vacuum-in-
sulated pipelines or for installation in
cold-box applications.
The cryogenic extension bonnet consists of a
metal bellows located directly above the
valve body and the insulating section above
the bellows seal.
The test connection (4.4) allows the pressure
to be monitored in order to check for leak-
age of the metal bellows.
The process medium flows through the valve
in the direction indicated by the arrow. The
position of the plug (3) is determined by
changes in the signal pressure acting on the
actuator diaphragm.
The stem connector (7) connects the plug
stem (6) with attached plug (3) and actuator
stem (8.1).
The plug stem is sealed by the metal bellows
and the backup stuffing box (4) with
spring-loaded PTFE-carbon V-ring packing
(4.2).
Fail-safe position:
Depending on how the springs (8.3) are ar-
ranged in the actuator, the control valve as-
sumes two different fail-safe positions:
Actuator stem extends
:
When the pressure is relieved or the supply
air fails, the actuator springs move the actu-
ator stem downwards and close the valve.
Actuator stem retracts:
When the pressure is relieved or the supply
air fails, the actuator springs move the actu-
ator stem upwards and open the valve.
4
EB 8093 EN
Design and principle of operation
Legend to Fig. 2
1
Valve body
1.1 Cryogenic extension bonnet
1.3 Nuts
2 Seat
3 Plug
4.1 Spring
4.2 Packing
4.3 Washer
4.4 Test connection
5 Valve bonnet
5.1 Guide bushing
5.2 Threaded bushing
5.3 Nuts
5.4 Travel scale indicator
5.5 Seal
6 Plug stem
6.1 Stem connector nut
6.2 Lock nut
6.3 Plug stem extension with metal bellows
6.3a and 6.3b with split extension bonnet
6.4 Bellows nut
6.5 Bellows flange
6.6 Guide bushing
(not with NPS 4 and 6/Class 150 - 300,
version with split plug stem extension)
6.7 Nut(s)
6.8 Washers
7 Stem connector
8 Actuator
8.1 Actuator stem
8.2 Annular nut
8.3 Springs
8.4 Rollng diaphragm
9 Loading pressure connection
10 Venting plug