SAMSON Type 3730 vs. Type 3731 Valve Positioners: Key Differences in Design and Applications

SAMSON Type 3730 and Type 3731 are digital electropneumatic valve positioners designed for pneumatic linear and rotary actuators.

Both series share a similar operating platform, including pneumatic components, feedback arrangements, and mounting options. The main difference is their enclosure design and protection concept.

The Type 3731 is available in versions corresponding to selected Type 3730 communication configurations. For example, 3731-3 and 3731-5 are associated with the HART and FOUNDATION Fieldbus versions respectively.

Therefore, the two series should not be differentiated simply by communication capability.

The suffix is important when selecting a SAMSON positioner.

• 3730-1: Basic digital 4–20 mA positioner with automatic initialization.

• 3730-2: Enhanced digital positioner with diagnostic functions.

• 3730-3: HART communication.

• 3730-4: PROFIBUS-PA communication.

• 3730-5: FOUNDATION Fieldbus communication.

• 3730-6: Enhanced diagnostics with supply and output pressure monitoring.

The corresponding 3731 versions should be checked against the required enclosure protection and communication configuration.

For standard industrial installations, the Type 3730 may be suitable when its enclosure protection meets the site requirements.

For hazardous locations requiring flameproof protection, the Type 3731 should be evaluated with the correct regional certification and installation requirements.

Before ordering, confirm the complete model number, actuator type, mounting arrangement, input signal, communication protocol, and required hazardous-area approvals.

We support sourcing of SAMSON digital valve positioners, including Type 3730 and Type 3731 versions.

For replacement or project inquiries, please provide the nameplate information and actuator details to help verify the correct model and configuration.