T 2549 EN

Type 2422/2425 Excess Pressure Valve

Self-operated Pressure Regulators

Application
Pressure regulators for set points from 0.05 to 2.5 bar · Valve nominal sizes DN 125 to 250 1) · Nominal pressure PN 16 to 40
Suitable for liquids, gases, and vapors up to 350 °C
The valve opens when the upstream pressure rises.

The excess pressure valves, consisting of a valve and actuator,

control the upstream pressure to an adjustable set point. The
medium pressure to be kept constant is transmitted through a
control line to the diaphragm of the actuator and consequently
the valve plug.

Special features
• Low-maintenance, medium-controlled proportional regula-
tors requiring no auxiliary energy
• Wide set point range and convenient set point adjustment
using a nut
• Exchangeable set point springs and actuator
• Spring-loaded, single-seated valve with upstream and
downstream pressures balanced by a stainless steel bel-
lows or by a balancing diaphragm
• Reduced KVS coefficients to adapt the regulator to the op-
erating conditions
• Standard low-noise plug · Special version with flow divid-
er ST 1 or ST 3 for further noise level reduction. See Data
Sheet u T 8081.
Fig. 1: Type 2422/2425 Excess Pressure Valve

Versions
Type 2422/2425 Excess Pressure Valve for DN 125 to 250 Special versions
Consisting of: Type 2422 Valve balanced by a bellows or a – With flow divider ST 1 or ST 3 for particularly low-noise
diaphragm with soft-seated plug · Body of cast iron, spheroi- operation
dal graphite iron, cast steel or cast stainless steel · Type 2425 – With metal-seated plug
Actuator with EPDM rolling diaphragm
– With FKM rolling diaphragm, e.g. for mineral oils or flam-
mable gases
– With NBR rolling diaphragm for flammable gases
– Version completely in stainless steel for nominal pressure
PN 16 to 40 · Details on request
– Actuator with two diaphragms
1) Valves larger than DN 250 on request
– With metal cover to protect the set point springs

SAMSON AKTIENGESELLSCHAFT · Weismüllerstraße 3 · 60314 Frankfurt am Main, Germany Edition December 2022
Phone: +49 69 4009-0 · Fax: +49 69 4009-1507 · samson@samsongroup.com · www.samsongroup.com
Principle of operation (see Fig. 2)
The medium flows through the valve in the direction indicated
by the arrow. The position of the plug (3) determines the flow 15 16

rate across the area released between plug (3) and valve 1
seat (2). The plug stem (5) with the plug is connected to the
p1 p2
actuator stem (11) of the actuator (10). 2

The upstream pressure p1 is regulated by the set point springs

3
(7) and the set point adjuster (6). When relieved of pressure,
the valve is closed by the force of the set point springs. 4
The upstream pressure p1 to be controlled is tapped upstream 4.1
of the valve and transmitted over the control line to the operat-
ing diaphragm (12) where it is converted into a positioning 14 5
force. This force is used to move the valve plug (3) according
to the force of the set point springs. The spring force is adjust-
able at the set point adjuster (6). 13.1 11
13
The principle of operation of the regulator balanced by a bel- 10
lows or diaphragm only differs concerning the pressure bal- 12
ancing. The valves balanced by a diaphragm have a balanc-
ing diaphragm (4.2) instead of a bellows (4.1). In both cases,
the forces created by the upstream and downstream pressures
that act on the valve plug are balanced out. 7

The valves can be supplied with flow divider ST 1 or ST 3. The

6
valve seat must be replaced on retrofitting the flow divider.

Type 2422/2425 Excess Pressure Valve

Type 2422 Valve, balanced by a bellows

P1 P2

1 Valve body
2 Seat (exchangeable) 4.2
3 Plug
4 Bellows housing
4.1 Balancing bellows
4.2 Balancing diaphragm
5 Plug stem
6 Set point adjuster
7 Set point springs
10 Actuator
11 Actuator stem
12 Operating diaphragm
13 Control line connection G ¼
13.1 Screw joint with restriction
Type 2422/2425 Excess Pressure Valve
14 Control line (to be provided on site)
15 Compensation chamber Type 2422 Valve, balanced by a diaphragm
16 Filler plug

p1 Upstream pressure
p2 Downstream pressure Fig. 2: Functional diagram

2 T 2549 EN
Table 1: Technical data · All pressures in bar (gauge)
Type 2422 Valve
Nominal size DN 125 DN 150 DN 200 DN 250
Nominal pressure PN 16, 25 or 40
Body Pressure-temperature diagram u T 2500
Max. permissible Metal seal: 350 °C · PTFE soft seal: 220 °C · EPDM or FKM soft seal: 150 °C
Plug balanced by a bellows
temperature NBR soft seal: 80 °C
Plug balanced by a diaphragm 150 °C
Leakage class according to IEC 60534‑4 ≤0.05 % of KVS coefficient
Conformity ·

Type 2425 Actuator

Set point ranges 0.05 to 0.25 bar · 0.1 to 0.6 bar · 0.2 to 1 bar · 0.5 to 1.5 bar · 1 to 2.5 bar 1)
Max. perm. Actuator area 320 cm² 640 cm²
pressure at actuator Pressure 3 bar 1.5 bar
Gases at the actuator 80 °C · Liquids 150 °C, with compensation chamber 350 °C
Max. permissible temperature
Steam with compensation chamber 350 °C
1) Set point ranges above 2.5 bar u T 2552 (Type 2335 Excess Pressure Valve)

Table 2: Materials · Material numbers according to DIN EN

Type 2422 Valve, balanced by a bellows
Nominal pressure PN 16 PN 25 PN 16, 25 and 40
Spheroidal graphite iron
Valve body Cast iron EN-GJL-250 Cast steel 1.0619 Stainless steel 1.4408
EN-GJS-400-18-LT
Seat 1.4006 1.4404
Plug 1.4404 1.4404 with PTFE seal
Seal for soft-seated plug PTFE · EPDM/FKM · NBR
Plug stem 1.4301
Metal bellows 1.4571
Bottom section 1.0305 1.4571
Body gasket Graphite on metal core
Type 2422 Valve, balanced by a diaphragm
Nominal pressure PN 16 PN 16/25 PN 16, 25 and 40
Spheroidal graphite iron
Valve body Cast iron EN-GJL-250 Cast steel 1.0619 Stainless steel 1.4408
EN-GJS-400-18-LT
Valve seat Red brass 1)

Plug Standard version Red brass 1)

· With EPDM soft seal or with PTFE soft seal
Balancing cases made of sheet steel DD11 · EPDM balancing diaphragm for liquids and non-flammable
Pressure balancing
gases or NBR diaphragm for flammable gases
Gasket Graphite on metal core
Type 2425 Actuator
Diaphragm cases DD 11 1.4301
Diaphragm EPDM with fabric reinforcement · FKM · NBR
Guide bushing DU bushing PTFE
Seals EPDM · FKM · NBR
1) Special version: 1.4409

Table 3: Valve balanced by a bellows · KVS coefficients and max. perm. differential pressures Δp
Type 2422 Valve, balanced by a bellows
KVS coefficients and max. permissible differential pressures Δp
Max. perm. differential
DN Standard KVS coefficients Flow divider ST 1 · KVS1 Flow divider ST 3 · KVS3
pressure Δp
125 190 150 95 16 bar
150 280 210 140 12 bar
200 420 315 200 10 bar
250 500 375 220 10 bar
Reduced KVS coefficients and max. permissible differential pressures Δp
125 80 60 40 20 bar
150 125 95 60 16 bar
200 280 210 140 12 bar
250 280 210 140 12 bar

T 2549 EN 3
Table 3.1: Valve balanced by a diaphragm · KVS coefficients and max. perm. differential pressures Δp
Type 2422 Valve, balanced by a diaphragm
KVS coefficients and max. permissible differential pressures Δp
Nominal size DN 125 DN 150 DN 200 DN 250
KVS coefficient 250 380 650 800
Max. perm. differential
12 bar 10 bar
pressure Δp

Dimensions
Type 2422 Valve balanced by a bellows

H2

Type 2422 Valve,

balanced by a bellows

H1

Type 2425 Actuator

ØD

Fig. 3: Dimension diagram of Type 2422 Valve balanced by a bellows with Type 2425 Actuator

Table 4: Dimensions in mm and weights · Type 2422 Valve balanced by a bellows · The values in parentheses apply to tempera-
tures from 220 to 350 °C
Type 2422/2425 · Balanced by a bellows
Nominal size DN 125 DN 150 DN 200 DN 250
Length L 400 480 600 730
Valve dimensions Height H1 460 (600) 590 (730) 730 (870)
Height H2 145 175 270
Set points Valve with actuator
Height H 990 1120 (1260) 1260 (1400)
0.05 to 0.25 bar
Actuator ØD = 390 mm, A = 640 cm²
Height H 990 (1130) 1120 (1260) 1260 (1400)
0.1 to 0.6 bar
Actuator ØD = 390 mm, A = 640 cm²
Height H 990 (1130) 1120 (1260) 1260 (1400)
0.2 to 1.0 bar
Actuator ØD = 390 mm, A = 640 cm²
Height H 940 (1080) 1070 (1210) 1210 (1350)
0.5 to 1.5 bar
Actuator ØD = 285 mm, A = 320 cm²
Height H 940 (1080) 1070 (1210) 1210 (1350)
1 to 2.5 bar
Actuator ØD = 285 mm, A = 320 cm²
Weight 1), approx. 92 kg 135 kg 277 kg 322 kg
1) The weight applies to the version with the material specifications EN-GJL-250/PN 16. Add +10 % for all other materials.

4 T 2549 EN
Type 2422 Valve, balanced by a diaphragm

H2
Type 2422 Valve, balanced
by a diaphragm
H1

H
Type 2425 Actuator

Fig. 4: Dimension drawing of Type 2422 Valve balanced by a diaphragm with Type 2425 Actuator

Table 5: Dimensions in mm and weights · Type 2422 Valve balanced by a diaphragm

Type 2422/2425 · Balanced by a diaphragm
Nominal size DN 125 DN 150 DN 200 DN 250
Length L 400 480 600 730
Height H1 285 310 380
Height H2 145 175 260
Set points Valve with actuator
Height H 815 840 910
0.05 to 0.25 bar
Actuator ØD = 390 mm · A = 640 cm²
Height H 815 840 910
0.1 to 0.6 bar
Actuator ØD = 390 mm · A = 640 cm²
Height H 765 790 860
0.2 to 1 bar
Actuator ØD = 285 mm · A = 320 cm² 1)

Height H 765 790 860

0.5 to 1.5 bar
Actuator ØD = 285 mm · A = 320 cm² 1)

Height H 765 790 860

1 to 2.5 bar
Actuator ØD = 225 mm · A = 320 cm²
Weight 2), approx. 75 kg 95 kg 250 kg 270 kg
1) Optionally with 640 cm² actuator
2) The weight applies to the version with the material specifications EN-GJL-250/PN 16. Add +10 % for all other materials.

T 2549 EN 5
Installation

– Install valves (balanced by a bellows or

diaphragm) with the actuator suspended
downward.

– Install pipelines horizontally with a slight

downward slope on both sides of the valve
to prevent condensed water from collecting.
– The direction of flow must match the direction indicated by
the arrow on the body.
– Connect a control line to the actuator from the point of
pressure tapping located approx. 1 m upstream of the
valve in the pipe wall or at the point of measurement of
the connected plant (with compensation chamber, if appli-
cable).

Accessories
– Screw joints with restriction for connection of the control
line (e.g. 6 or 12 mm pipe).
– Only applicable to valves balanced by a bellows: com-
pensation chamber for condensation and to protect the
operating diaphragm against extreme temperatures. The
chamber is required for steam and liquids above 150 °C.
For detailed information on accessories refer to Data Sheet
u T 2595

Ordering text
Type 2422/2425 Excess Pressure Valve
DN ...,
Body material ..., PN …
KVS coefficient ..., set point range … bar
Balanced by a bellows or diaphragm
Optionally, special version ..., accessories ...

2023-01-04 · English

Specifications subject to change without notice T 2549 EN