Samson 3730-3 Electropneumatic Smart Positioner
Overview
The Samson 3730-3 is a HART-enabled electropneumatic smart positioner that converts a 4-20 mA control signal into precise pneumatic actuator movement, giving control valves accurate, repeatable positioning with full digital diagnostics. It is used by process engineers and maintenance teams across Oman and the GCC on control valves throughout oil and gas, petrochemical, power generation, and water treatment facilities where tight valve positioning accuracy directly affects process quality and efficiency.
As part of Samson’s widely specified Series 3730 positioner family, the 3730-3 combines the mechanical robustness expected of a Samson valve accessory with modern HART communication, letting plant engineers configure, calibrate, and diagnose the positioner remotely through a DCS or handheld communicator rather than requiring a field visit for every adjustment.
Operating Principle
The 3730-3 accepts a standard 4 to 20 mA input signal, with reverse-polarity protection and reliable operation down to 3.8 mA, and converts it into a proportional pneumatic output using supply air pressure from 1.4 to 7 bar (20 to 105 psi), conforming to ISO 8573-1 air-quality standards. Internal software allows selectable output pressure limits of 1.4, 2.4, or 3.7 bar (±0.2 bar) to match the actuator’s spring range, and HART communication (350-450 Ω receiving, ~115 Ω sending impedance) layers digital configuration and diagnostic data on top of the standard analog loop.
Engineering Design of the Samson 3730-3
The positioner mounts directly to Samson Type 3277 actuators or via NAMUR rib, VDI/VDE 3845/3847, or rod-type yoke attachment per IEC 60534-6-1, giving it broad compatibility with linear and rotary control valve actuators from multiple manufacturers. Adjustable travel spans 3.6 to 30 mm for direct Type 3277 mounting, up to 300 mm for NAMUR/VDI-VDE configurations, or 24 to 100° of opening angle for rotary actuators. The housing is rated IP 66/NEMA 4X in die-cast aluminum or stainless steel, with a standard operating range of −20 to +80°C, extendable to −55°C in a special low-temperature version, and local configuration is supported through the SSP interface with TROVIS-VIEW software.
Key Features
- 4-20 mA input with HART communication
- Supply air 1.4-7 bar (20-105 psi), ISO 8573-1 compliant
- Selectable output pressure limits: 1.4, 2.4, or 3.7 bar
- Compatible with linear (3.6-300 mm) and rotary (24-100°) actuators
- IP 66/NEMA 4X enclosure, aluminum or stainless steel
- Operating range −20 to +80°C (to −55°C special version)
- Local configuration via SSP interface and TROVIS-VIEW software
Industrial Applications
Across Muscat, Sohar, and Salalah, the Samson 3730-3 is used on control valves throughout refineries, petrochemical plants, gas processing facilities, and power stations, where precise, HART-diagnosable valve positioning supports both process control quality and predictive maintenance. Its broad actuator compatibility makes it a practical upgrade path when retrofitting older pneumatic-only positioners with digital communication capability.
The positioner is also specified in water and desalination treatment plants and general process industries across the region, where its IP66-rated enclosure and wide temperature range suit both indoor process areas and exposed outdoor valve stations.
Technical Specifications
| Parameter | Specification |
|---|---|
| Input Signal | 4-20 mA, HART communication |
| Supply Air Pressure | 1.4-7 bar (20-105 psi) |
| Output Pressure Limits | 1.4, 2.4, or 3.7 bar (±0.2 bar), selectable |
| Travel Range | 3.6-300 mm (linear); 24-100° (rotary) |
| Enclosure | IP 66/NEMA 4X, aluminum or stainless steel |
| Operating Temperature | −20 to +80°C (to −55°C special) |
| Configuration | SSP interface, TROVIS-VIEW software |
| Travel, direct attachment to Type 3277 | 3.6 to 30 mm |
| Travel, IEC 60534-6 (NAMUR) and VDI/VDE 3847 attachment | 3.6 to 300 mm |
| Set point | 4 to 20 mA two-wire; minimum span 4 mA; static destruction limit 100 mA |
| Minimum current | 3.6 mA for display; 3.8 mA for operation |
| Load impedance | Max. 8.2 V (corresponds to 410 Ω at 20 mA) |
| Air quality to ISO 8573-1 | Particle size and density Class 4; oil content Class 3; pressure dew point Class 3 |
| Deviation / hysteresis / sensitivity | Max. 1 % / max. 0.3 % / max. 0.1 % |
| Air consumption, steady state | Approx. 110 l(n)/h, independent of supply pressure |
| Air output capacity | Fill: 8.5 m³(n)/h at 6 bar differential; vent: 14.0 m³(n)/h at 6 bar differential |
| Transit time | Filling and venting separately adjustable up to 240 s by software |
| Influences | Temperature max. 0.15 %/10 K; supply air none; vibration max. 0.25 % up to 2000 Hz and 4 g |
| Weight | Approx. 1.0 kg (die-cast aluminum housing); approx. 2.2 kg (stainless steel housing) |
Type 3730-3 Attachment Options, Travel Ranges and Pneumatic Performance
The usable travel depends on how the positioner is mounted. Directly attached to a SAMSON Type 3277 actuator (175 to 750 cm²) it covers 3.6 to 30 mm. With a NAMUR bracket to IEC 60534-6-1 or with the VDI/VDE 3847 version it covers 3.6 to 300 mm, and on rotary actuators to VDI/VDE 3845 it covers opening angles of 24 to 100 degrees. Within the initialized range the working travel can be narrowed to one fifth. Any mounting position is permitted except suspended, and a reversing amplifier is needed for double-acting springless actuators.
SAMSON specifies a characteristic deviation of at most 1 %, hysteresis of at most 0.3 % and sensitivity of at most 0.1 %. Steady-state air consumption is about 110 normal litres per hour regardless of supply pressure. At a 6 bar differential the booster delivers 8.5 normal cubic metres per hour when filling and 14.0 when venting, falling to 3.0 and 4.5 at 1.4 bar. Stroking time can be slowed separately for filling and venting up to 240 seconds, and the output pressure can be limited by software to 1.4, 2.4 or 3.7 bar.
On the electrical side the positioner is a two-wire device with a load of no more than 8.2 V, equal to 410 Ω at 20 mA. The display works from 3.6 mA and control from 3.8 mA, the minimum split-range span is 4 mA and the static destruction limit is 100 mA. Supply air must meet ISO 8573-1 Class 4 for particles and Class 3 for oil and dew point. Temperature influence is at most 0.15 % per 10 K, supply pressure has no influence, and vibration influence is at most 0.25 % up to 2000 Hz and 4 g.
Type 3730-3 Diagnostics, Options, SIL Use and Explosion Protection
EXPERTplus valve diagnostics are integrated in the Type 3730-3 as standard. The positioner continuously monitors its zero point, has an internal temperature sensor and operating-hours counter, and reports faults as a condensed state according to NAMUR NE 107 through a fault alarm contact or the optional position transmitter. Two programmable software limit contacts are standard. Options listed by SAMSON are an inductive limit contact, an analog 4-20 mA position transmitter, a 24 V DC solenoid valve for forced venting, a binary input, an external position sensor and a leakage sensor.
For safety-instrumented systems the emergency venting function, triggered by a 0 mA set point or by the optional solenoid valve, can be used up to SIL 2 as a single device and SIL 3 in redundant configuration, subject to IEC 61511. Explosion-protected versions include intrinsic safety to ATEX (II 2 G Ex ia IIC Gb) and IECEx, FM and CSA approvals, a dust version Ex tb IIIC and a Zone 2 version Ex nA. Enclosure rating is IP 66 / NEMA 4X, and EMC complies with EN 61000-6-2, EN 61000-6-3, EN 61326-1 and NAMUR NE 21.
Samson 3730-3 FAQ
What is the Samson 3730-3?
A HART-enabled electropneumatic smart positioner that converts a 4–20 mA signal into precise pneumatic actuator movement for control valves, with digital diagnostics.
What supply air and input signal does it need?
A 4–20 mA input, reliable down to 3.8 mA, and supply air of 1.4 to 7 bar (20 to 105 psi) conforming to ISO 8573-1.
Which actuators can it mount on?
Samson Type 3277 actuators directly, or via NAMUR rib, VDI/VDE 3845/3847 or rod-type yoke attachment per IEC 60534-6-1. Travel spans 3.6 to 300 mm for linear and 24 to 100° for rotary actuators.
What are the environmental ratings?
IP 66 / NEMA 4X in die-cast aluminum or stainless steel, with an operating range of −20 to +80 °C and a special version down to −55 °C.
How is the 3730-3 configured?
Remotely through a DCS or HART communicator, or locally through the SSP interface with TROVIS-VIEW software.
Request a Quote for Samson 3730-3 Electropneumatic Smart Positioner
Seven Star LLC supplies the Samson 3730-3 electropneumatic smart positioner as an experienced supply partner to process industries across Oman and the GCC. Contact our engineering team for a formal quotation and configuration support for your control valve application.
Browse the full Samson range or see more Valve Positioner products supplied by Seven Star LLC in Oman and the GCC.
Samson valve, actuator and positioner types
Samson builds a control valve from modules. The Type 3241 globe valve is the general-service body of Series 240, and the Type 3251 is the Series 250 body for higher pressure ratings. Either one is combined with a Type 3271 pneumatic diaphragm actuator or a Type 3277, whose yoke allows the positioner to be attached directly with a concealed travel linkage. The positioners listed are the Type 3725 and the Type 3730 family: the 3730-1 as the basic electropneumatic version, sold in its current generation as TROVIS 3730-1, and the 3730-3 with HART communication and valve diagnostics. Samson also makes PROFIBUS PA and FOUNDATION fieldbus variants in the same family, plus self-operated pressure and temperature regulators.Where Samson valves are used
Samson control valves throttle steam, gas and liquids in chemical and petrochemical units, refineries, gas processing, power stations, water and desalination plants, and food production. Many reach site as part of a skid or package, so the plant instrument team often meets them first when a positioner or actuator needs replacing. We supply these items to end users and contractors throughout the GCC.Ordering Samson parts: what we need
Every Samson device has a nameplate with the type, a configuration ID (Var-ID) and a serial number. A photo of that plate is the surest route to an exact match. Without it, please send:- Valve: type, DN or NPS, pressure rating, body and trim material, Kvs or Cv, plug and seat style, packing and bonnet type
- Actuator: type, effective area in cm², bench range, fail action and travel
- Positioner: full type code including Ex protection, communication and options such as limit switches or position transmitter
Browse Samson products by category: Control Valves, Valve Positioner, Valve Actuator.
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