Samson 3372 Mounting and operating instructions - Ation
8
EB 8313-3 EN
Design and principle of operation
2 Design and principle of oper-
ation
TheType 3372ElectropneumaticActuatoris
mainly used for attachment to Series V2001
Valves:
−
Type 3321 Globe Valve
−
Type 3323 Three-way Valve
−
Type 3531GlobeValveforHeatTransfer
Oil
−
Type 3535Three-wayValveforHeat
Transfer Oil
The actuator mainly consists of two dia-
phragm cases (1 and 2) with a diaphragm
(4) and internal springs (10). The actuator is
connected to the valve bonnet by a rod-type
yoke.TheType 3725ElectropneumaticPosi-
tioner is attached to the rod (33) with the
largest diameter using a support element
(61). This positioner converts the control sig-
nal received from a control system (4 to
20 mAreferencevariable)intoaproportion-
al pressure signal.
The signal pressure (p
st
, S port) creates a
force at the diaphragm surface which is op-
posed by the compression springs (10) in the
actuator. The number of springs and their
compression determine the bench range (sig-
nal pressure range). The travel is always pro-
portional to the signal pressure.
The stem connector connects the actuator
stem (7) to the plug stem of the mounted
valve.
2.1 Versions
2.1.1 Type 3372 (120 cm²)
−
Actuator with die-cast aluminum housing
−
Standard use for attachment to
Type 3321andType 3323Valvesin
DN 15to50aswellasType 3531and
Type 3535ValvesinDN 15to80(corre-
spondstoFormBinTable 1).
Optionally,theactuatorcanbefittedwitha
mechanically adjustable travel stop or a
manual override.
2.1.2 Type 3372 (350 cm²)
−
Actuator with sheet steel housing (see
Fig. 1)
−
Standard use for attachment to
Type 3321ValvesinDN 65to100as
wellasType 3323ValvesinDN 65to
100for15or30 mmtravel(corresponds
toFormCinTable 1).
Thisactuatorversioncannotbefittedwitha
manual override or travel stop.