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3 Design and principle of oper-
ation
Î See Fig. 3-1 and Fig. 3-2
The differential pressure regulators basically
consist of the valve body (1) with balanced
plug (3) as well as a closing actuator with an
operating diaphragm.
In Type 45-1 and Type 45-3, the set point
spring (8) installed into the valve determines
the set point. Whereas, in Type 45-2 and
Type 45-4, the set point can be adjusted by
the set point springs (8) in the actuator.
The regulators are designed to maintain a
constant differential pressure between the
high-pressure and low-pressure lines to an
adjustable set point. The valve closes when
the differential pressure exceeds the adjusted
set point.
Types 45-1 and 45-2 · Installation in the
flow pipe
Type 45-1 · The set point is fixed.
Type 45-2 · The set point can be adjusted as
required within the set point range.
The medium flows through the regulator in
the direction indicated by the arrow. The
pressure in the valve outlet (high pressure) is
transferred to the high-pressure chamber of
the actuator over the attached control line
(11) and the low pressure from the return
flow pipe is transferred to the low-pressure
chamber of the actuator over a control line
(12) to be installed on site. See Fig. 3-3.
EB 3124 EN
Design and principle of operation
Types 45-3 and 45-4 · Installation in the re-
turn flow pipe
Type 45-3 · The set point is fixed.
Type 45-4 · The set point can be adjusted as
required within the set point range.
The pressure upstream of the valve (low pres-
sure) is transferred to the low-pressure cham-
ber of the actuator through the borehole (13)
and the high pressure from the flow pipe is
transferred to the high-pressure chamber of
the actuator over a control line (11) to be in-
stalled on site.
The differential pressure creates a position-
ing force at the operating diaphragm which
moves the valve plug depending on the force
of the set point spring(s) (8/10). See
Fig. 3-3.
Types 45-1 and 45-3
Type 45-3
only
13
11
12
11
8
Fig. 3-1: Functional diagrams of the differential
pressure regulators
1
2
3
4
5
6
7
20
14
3-1
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