14 EB 2517 EN
Design and principle of operation
1 Valve body
2 Seat
3 Plug
4 Balancing bellows
5 Plug stem
5.1 Bellows
6 Set point adjuster
7 Set point springs
7.1 Spring plate
7.2 Nut
7.3 Cap screw
7.4 Needlebearingandaxialdisk
8 Crossbeam
8.1
Stud bolt
(view drawn turned by 90°)
8.2 Nuts for stud bolts
8.3 Tapped holes
9 Fastening nuts
10 Diaphragm actuator/bellows actuator
11 Actuator stem
12 Operating diaphragm
12.1 Operating bellows
13 Diaphragm plate
14 Diaphragm plate nut
15 Nuts and bolts
16
ControllineconnectionG¼
(with screw joint with restriction when used
with steam)
17
Control line (to be provided on site)
(available as control line kit for direct
pressure tapping at the body uT2595)
18 Compensation chamber
19 Filler plug
3 Design and principle of oper-
ation
Î RefertoFig.3
TheType41-73ExcessPressureValvecon-
sistsofaType2417OpeningValveanda
Type2413Actuator.Thevalveandactuator
are delivered separately and must be assem-
bled according to the instructions in sec-
tion6.1.1.
Theexcesspressurevalveisusedtomaintain
the pressure upstream of the valve to an ad-
justed set point.
Theprocessmediumowsthroughthevalve
between seat (2) and plug (3) in the direc-
tion indicated by the arrow on the body. The
position of the valve plug determines the
owrateand,asaresult,thepressureratio
across the valve. The plug stem is sealed by
a frictionless bellows (5.1). The upstream
pressure p
1
is transmitted over the compen-
sation chamber (18) and control line (17) to
the operating diaphragm (12) (operating
bellows (12.1) in the version with bellows
actuator) where it is converted into a posi-
tioning force. This force is used to move the
valve plug depending on the force of the set
point springs (7). The spring force is adjust-
able at the set point adjuster (6). The valves
with K
VS
4andhigherhaveabalancingbel-
lows (4). The upstream pressure acts on the
outside of the bellows and the downstream
pressure on the inside of the bellows. As a
result, the forces produced by the upstream
and downstream pressures acting on the
plug are balanced out.
The valve closes when the downstream pres-
sure rises.