Design And Principle Of Operation - Samson 2479 Mounting And Operating Instructions

3 Design and principle of oper-
ation
Î See Fig. 3-1 and Fig. 3-2
The regulator consists of the Type 2479
Valve with restriction, seat and plug and the
closing actuator with operating diaphragm
as well as the Type 2430 Control Thermo-
stat with set point adjuster, capillary tube
and temperature sensor.
The regulator is used to maintain the differ-
ential pressure and temperature to their ad-
justed set points. The flow rate can be limited
by the restriction (1.2) integrated in the valve
body.
Versions for safety equipment are additional-
ly equipped with a Type 2403 Safety Ther-
mostat (as safety temperature monitor DPR/
TR/STM) or with a Type 2439 Safety Tem-
perature Limiter (as safety temperature limit-
er DPR/TR/STL). See documents listed under
'Referenced documentation' in the 'Safety in-
structions and measures' section.
The medium flows through the valve in the
direction indicated by the arrow on the valve
body. The flow rate is determined by the ar-
ea released by the plug (3) and the adjust-
able restriction (1.2).
The high pressure of the plant (flow pipe) is
transmitted to the high-pressure side of the
actuator through the control line (11) mount-
ed on site. The low pressure downstream of
the restriction acts on the low-pressure side
of the operating diaphragm (6.1) through a
hole in the plug.
EB 3132-3 EN

Design and principle of operation

The differential pressure generated across
the restriction is converted into a positioning
force by the operating diaphragm. This force
is used to move the plug depending on the
force of the set point spring (5).
The temperature of the medium creates a
pressure in the temperature sensor. This pres-
sure is transferred to an operating bellows
(23) through a capillary tube (24) where it is
converted into a positioning force. This force
moves the plug (3) over the pin of the oper-
ating element (8), dependent on the force of
the spring (21) loaded by the set point ad-
juster (22).
The largest signal is always used to control
the regulator.
The valve closes as the controlled variable
rises.
3-1