Design And Principle Of Operation - Samson 42-36 Mounting And Operating Instructions

3 Design and principle of oper-
ation
Î See Fig. 3-1 and Fig. 3-2
Type 42-36 · The flow regulator is used to
limit the flow rate in the pipeline. The set
point is adjusted at the restriction.
The regulator basically consists of a
Type 2423 Valve with seat, plug and set
point adjuster as well as a Type 2426 Actua-
tor (closing) with operating diaphragm.
Valve and actuator are delivered separately
and must be fastened together on site using
a coupling nut.
Type 42-36 DoT · This version can also con-
trol or limit the temperature by mounting a
double adapter with thermostat. Read the
mounting and operating instructions:
u EB 3019 for double adapter DoT
and
u EB 2231 for Type 2231 to 2234 Control
Thermostats
The medium flows through the valve in the
direction indicated by the arrow. The areas
released by the restriction (1.4) and the
valve plug (3) determine the flow rate.
In fully balanced valves, the forces acting on
the valve plug created by the upstream and
downstream pressures are balanced by a
balancing bellows (5) or balancing dia-
phragm (5.1) (DN 65 to 250, balanced by a
diaphragm).
EB 3015 EN

Design and principle of operation

Regulators balanced by a bellows or a
diaphragm only differ in the pressure
balancing principle applied. Valves
balanced by a diaphragm have a balancing
diaphragm (5.1) instead of the balancing
bellows (5). The downstream pressure p
on the bottom of the diaphragm and the
upstream pressure p
diaphragm. As a result, the forces created
by the upstream and downstream pressures
acting on the plug are balanced out.
The pressure upstream of the restriction (1.4)
is transferred over the control line (18) to the
bottom diaphragm chamber and the
pressure downstream of the restriction (1.4)
is transferred through the hollow plug stem
(7) past the diaphragm stem (6) to the top
diaphragm chamber of the actuator. This
differential pressure creates a positioning
force at the operating diaphragm (12),
which moves the valve plug depending on
the force of the differential pressure springs
(14). For example, if the flow rate increases,
the differential pressure (at the restriction)
increases as well. The actuator and plug
stems move in the closing direction, causing
the flow rate to decrease until it reaches the
set point adjusted at the restriction (1.4).
When the flow rate starts to drop, the
described procedure is reversed.
on the top of the
1
acts
2
3-1