T 8313 EN
Type 3372 Electropneumatic Actuator

Application
Electropneumatic linear actuators for attachment to Type 3214 and Type 3260 Valves as well as Series V2001 Valves
Rated travel

15 and 30 mmActuator area

120 and 350 cm²

The Type 3372 Electropneumatic Actuator is available in thefollowing versions:• Version with Type 3725 Positioner (direct attachment),
120 cm² actuator area and 15 mm rated travel (Fig. 1)

Fig. 1: Type 3372 Actuator · 120 cm²
actuator area · With Type 3725
Positioner (direct attachment)• Version with Type 3725 Positioner (direct attachment),
350 cm² actuator area and 15 or 30 mm rated travel(Fig. 2)
The actuators are suitable for attachment to Series V2001
Valves (e.g. Type 3321, Type 3323, Type 3531, Type 3535)
as well as Type 3214 and Type 3260 Valves. The actuators
mainly consist of two diaphragm cases, a rolling diaphragmand internal springs. For throttling service, a Type 3725
Positioner is mounted to the rod-type yoke using a support
element.
Further versions–Permissible operating temperatures from –35 to +90 °C–Version ready for the attachment of a Series 3730 Positioner, 120 cm² actuator area and 15 mm rated travel or
350 cm² actuator area and 15 or 30 mm rated travel–

Explosion protection for a mounted Type 3725 or Series 3730 Positioner according to the documentation ofthe positioner used (see Table 1.2)

Fig. 2: Type 3372 Actuator · 350 cm²
actuator area · With Type 3725
Positioner (direct attachment)

Accessories–

Type 4744‑2 Limit Switch (Fig. 3) · With explosion protection and degree of protection according to the documentation of the limit switch (see Table 1.2) · Clamping plate
can be used to mount it · See Data Sheet u T 8367

Fig. 3: Type 3372 Actuator (120 cm²) with additional
Type 4744‑2 Limit Switch

SAMSON AKTIENGESELLSCHAFT · Weismüllerstraße 3 · 60314 Frankfurt am Main, Germany
Phone: +49 69 4009-0 · Fax: +49 69 4009-1507 · samson@samsongroup.com · www.samsongroup.com

Edition February 2024

Principle of operation

Tight-closing function

The positioner mounted on the Type 3372 ElectropneumaticActuator ensures a predetermined assignment of the valve position (controlled variable x) to the input signal (reference variable w). It compares the input signal received from a control
system to the travel of the valve and issues a corresponding
output signal pressure pst (output variable y) for the actuator.
The signal pressure pst creates the force F = pst · A at the diaphragm surface A which is opposed by the springs (10) in theactuator. The bench range is determined by the number ofsprings used and their compression, taking into account therated travel. The travel H is proportional to the signal pressure
pst. The direction of action of the actuator stem (7) depends on
how the springs are installed in the actuator and the locationof the signal pressure connection (S).

The electropneumatic actuator is completely filled with air orvented as soon as the reference variable falls below or exceeds a certain value.

Further details on the principle of operation of the positioner:– Type 3725 (Data Sheet u T 8394)– More details on Series 3730 in Data Sheets u T 8384-X
and u T 8484-X.

Actuator stem extends (FA)When the reference variable falls below the switching point of
4.08 mA, the actuator is fully vented. This causes a mounted
globe valve to close. In three-way valves, port B is closed
when the valve is used for mixing service and port A is closed
when the valve is used for diverting service.
Actuator stem retracts (FE)When the reference variable exceeds the switching point of
19.95 mA, the actuator is filled with air. This causes a mounted globe valve to close. In three-way valves, port A is closed
when the valve is used for mixing service and port B is closed
when the valve is used for diverting service.

Fig. 4: Type 3372 Electropneumatic Actuator with 120 cm²actuator area for the direct attachment of aType 3725 Positioner

155.1
115211021

415

1025.14040424241741
7Fig. 5: Type 3372 Electropneumatic Actuator with350 cm² actuator area for the direct
attachment of a Type 3725 Positioner
151105

Legend for Fig. 4 and Fig. 5
1, 2 Diaphragm case
4Diaphragm
5Diaphragm plate
7Actuator stem
10Spring
15
Collar nut
20
Hex bolt
21
Hex nut
25
Washer27
Compressor
33
Rod40
Radial shaft seal
41
Wiper ring
42
Plain bearing
54
Hex nut (for 33)
60
Plate61
Support element24202521227404241617336054

T 8313 ENTable 1: Technical data
Table 1.1: Electric data of Type 3372
Type 3372 with directly attached Type 3725 Positioner 1)
Actuator area

120 cm²

Rated travel

15 mm

Function (mounted device)
Reference variable

350 cm²
15 mm

Electropneumatic positioner with self-calibrating, automatic adaptation to valve and actuator
4 to 20 mA (reverse polarity protection)

Split-range operation

4 to 11.9 mA and 12.1 to 20 mA

Static destruction limit±33 V

Minimum current

3.8 mA

Load impedance

Max. 6.3 VSpan adjustment

Self-adjusting

Direction of action

Adjustable: increasing/increasing or increasing/decreasing

Tight-closing function

w < 1 % and w > 99 %Operation30 mm

Can be individually activated or deactivated using capacitive keys (P9 or P10)

Hysteresis≤0.3 %

Variable position–

Switching accuracy–

Air consumption in steady state≤100 ln/h with a supply pressure up to 6 bar and a signal pressure of 0.6 bar

Actuator (supply)

At Δp = 6 bar: 8.5 mn³/h
At Δp = 1.4 bar: 3.0 mn³/h
KVmax (20 °C) = 0.09

Actuator (exhaust)

At Δp = 6 bar: 14.0 mn³/h
At Δp = 1.4 bar: 4.5 mn³/h
KVmax (20 °C) = 0.15

Air outputcapacity

Temperature range 2)–25 to +80 °C 3)

Degree of protection

IP 66 4)

Electropneumatic or pneumaticconnection

Separate from actuator (in the positioner)

Electromagnetic compatibility

Complying with EN 61000-6-2, EN 61000-6-3 and NAMUR Recommendation NE 21

ReadingWith LEDs

Initialization

AutomaticOperation

Using capacitive keys

Zero calibration
Associated documentation
1)
2)
3)
4)

Automatic (activated by P15 or P16)
u EB 8313-3, u EB 8394 or u T 8394

Versions with Type 3730-x or Type 3731-x Positioner on request
Observe temperature range of mounted devices (positioner etc.).
–35 to +90 °C with Type 373x‑x Positioner and metal cable glands
Other ratings possible when a Type 373x-x Positioner is mounted. See corresponding mounting and operating instructions

T 8313 EN

3Table 1.2: Explosion protection certificates for Type 3372 in combination with a positioner and any optionally mounted limit
switchThe listed technical data for actuators used in hazardous areas may be further restricted by the limits specified in the test
certificates of the positioner and any optionally mounted limit switch.
See documentation of the positioner used and any optionally mounted limit switch for the explosion protection certificates.
Mounted device

See the mounting and operating instructions for explosion protection certificatesType 3725 Positioner

u EB 8394

Type 3730-0 Positioner

u EB 8384-0

Type 3730-4 Positioner

u EB 8384-4

Type 3730-5 Positioner

u EB 8384-5

Type 3730-6 Positioner

u EB 8384-6

TROVIS SAFE 3730-6 Positioner

u EB 8384-6S

TROVIS 3730-1 Positioner

u EB 8484-1

TROVIS 3730-3 Positioner

u EB 8484-3

Type 4744 Limit Switch

u EB 8367

Table 1.3: Further technical data for Type 3372
Type 3372 with directly attached Type 3725 Positioner
Actuator area

120 cm²

Rated travel

15 mm

350 cm²
15 mm

30 mm

Pneumatic data
Tight-closing function

Bench range
Supply pressure

Stemretracts (FE)
0.4…1.4

Stem
retracts (FE)Stemextends(FA)

1.4 to 2.3

Stem
extends(FA)

Stemretracts (FE)Stemextends(FA)

Stemretracts (FE)Stemextends(FA)

2.1 to 3.3

1.5 to 2.1

2.1 to 2.7

1.5 to 2.7

2.2 to 3.8

Max. 6 bar 1)

Max. 6 barMaterials
Actuator housing

Aluminum, powder coating

1.0332Diaphragm

NBR

NBR

Actuator stem

1.43051.4401/1.4404

3.3

15

Form B or Form C(see Table 2)

Form C

Weight (without positioner)kg (approx.)
Attachment

Conformity1)With "actuator stem extends" fail-safe action, the supply pressure must not exceed the upper bench range value by more than 1.5 bar.

Table 1.4: Technical data of Type 4744‑2 Limit Switch
Type 4744-2 Limit Switch
Travel range

15 mm

Permissible load

AC voltage: 250 V/5 A
DC voltage: 250 V/0.4 A

Temperature range–20 to +60 °C

Degree of protection

IP 66

Explosion protection

Flameproof enclosure II 2G Ex db IIC T6-T5

Approx. weight
Associated documentation

40.4 kgu T 8367

T 8313 EN

Mounting types
There are two types of mounting depending on the valve/actuator combination: mounting using a crossbeam or rods.
When the actuator is mounted to the valve using a crossbeam (form B, Fig. 6), the actuator is fastened to the valve bonnet using acentral nut.
When the actuator is mounted using rods (form C, Fig. 7 and Fig. 8), the actuator is connected to the valve bonnet using rods. In
this case, a crossbeam is not required for mounting the actuator.
Table 2: Mounting types (see Fig. 6, Fig. 7 and Fig. 8)
Type 3372
Actuator withType 3725
Positioner (directattachment)
Type ... Valve

Actuator area

120 cm²

Travel15 mm

350 cm²15 mm

30 mm

Nominal size DN

3321

15 to 50

Form B––

3321

65 to 100

Form C

Form C–

3321

100––Form C3323

15 to 50

Form B––332365 to 80

Form C

Form C–3323

100––

Form C3531

15 to 80

Form B––3535

15 to 80

Form B––3214

65 to 100

Form B––3214125 to 250––

On request

3260

65 to 80

Form B––

3260

100 to 150––

Form B

Fig. 6: Form B: mounting using crossbeam

T 8313 EN

Fig. 7: Form C: mounting using rods(120 cm²)

Fig. 8: Form C: mounting using rods (350 cm²)5

1535030

Fail-safe action: actuator stem retracts
(FE)

34

5

60.4 to 1.44

0.5

1.7

0.7

1.9

3.1

–

–

1800

1.4 to 2.3

8

1.7

2.8

–

0.8

2

3.2

4.4

12

2.5

4.0

–

–––

–

8––

–

3.15

6.65

6.65

6.65

67.35

9.5

–––––

1800

2.1 to 3.35250

1.5 to 2.1

5250

2.1 to 2.7

No. of springs

2

1800

Additional possible spring compression

Bench range [bar] (signal pressure
range at rated travel)

120

Fail-safe action: actuator stem extends(FA)

Travel volume at rated travel [cm³]Rated travel [mm]Actuator area [cm²]

Table 3: Bench ranges of Type 3372 Actuator–

Spring force at
0 mm travel [kN]Spring force at
rated travel [kN]Spring force [kN] at rated traveland supply pressure [bar] of10500

1.5 to 2.7

8

–

–

–

1.05

4.55

8.05

11.55

10500

2.2 to 3.8

12

7.7

13

–

–

–

–

–

Dimension diagrams · All dimensions in mm

Specifications subject to change without notice

350 cm² actuator area
(actuator stem retracts/extends)

T 8313 EN

2024-02-09 · English

182

120 cm² actuator area
(actuator stem retracts/extends)

231

Ø280

Ø168