Samson 3730-2 Electropneumatic Positioner — Smart I/P Positioner for Process Control Valves

SAMSON · TYPE 3730-2 · I/P POSITIONER · IN STOCK

The Samson 3730-2 is a German-engineered electropneumatic smart positioner from Samson, the Frankfurt-based process control specialist. It converts a 4-20 mA setpoint — with optional HART, FOUNDATION Fieldbus, or PROFIBUS-PA communication — into a stable 0.2-1.0 bar pneumatic output that drives pneumatic globe, rotary, and linear-actuated control valves. Designed for chemical, oil & gas, power, and water / wastewater service, the 3730-2 is widely deployed as the smart positioner layer on top of valve assemblies controlled by Siemens SIMATIC, Allen-Bradley ControlLogix, or Mitsubishi MELSEC analog output channels. The integrated LCD with rotary pushbutton simplifies on-site calibration, while the on-board partial stroke test (PST) supports SIL 3 safety instrumented functions. Send your RFQ to Moritta@KOEED.COM to receive availability and price within 24 hours.

Key Technical Specifications

Application Scenarios & Where It Fits

The Samson 3730-2 is built for continuous process duty. It is the smart positioner of choice for modulating control valves across the most demanding continuous-process industries:

• Chemical and petrochemical plants — flow, pressure, level, and temperature loops on globe valves
• Oil & gas upstream and midstream — wellhead choke control and separator pressure regulation
• Power generation and district heating — feedwater, attemperator, and steam conditioning duty
• Food & beverage and pharmaceutical — hygienic service with stainless steel linkage options
• Pulp & paper — stock preparation and chemical recovery boiler control
• Water and wastewater treatment — chemical dosing and aeration basin modulating valves
• Mineral processing and mining — slurry line isolation and reagent addition
• Building automation — large HVAC chilled-water and heating-coil regulation

In a typical loop the 3730-2 receives its 4-20 mA setpoint from the analog output of an Omron SYSMAC CJ2 CPU, a Panasonic FP7 PLC, or a dedicated DCS card. For SIF / ESD service, the integrated partial stroke test means the positioner can self-validate on a schedule without taking the valve fully off-line — a useful advantage when the rest of the rack is built on Schneider Modicon or Yaskawa MP2300 controllers.

Integration & Wiring Notes

Wiring the 3730-2 into a new or existing control loop is straightforward, but a few points are worth flagging up front:

• Two-wire current loop. The positioner is powered directly from the 4-20 mA signal and acts as a low-impedance load. Check the analog output module's compliance voltage covers the positioner plus loop resistance — a typical 6ES7 331 or 1756-IF8H channel is fine.
• HART / FF / PROFIBUS variants. Order the matching communication board — the suffix on the part number declares the protocol. HART is the most common retrofit; FOUNDATION Fieldbus is preferred for greenfield DCS builds.
• Pneumatic supply. Use clean, dry instrument air at 1.4 bar minimum, 6 bar maximum. A coalescing filter upstream is strongly recommended for outdoor or compressor-served plants.
• Cable gland and conduit. The IP66 / NEMA 4X enclosure accepts M20 entries; seal unused entries with brass blanking plugs to keep the rating intact.
• Shielding and grounding. For HART / FF, twisted shielded pairs with single-point ground at the cabinet end prevent noise pickup near VFDs and servo drives from Fanuc or Yaskawa Sigma-7 cabinets.
• DTM / EDD files. Samson supplies device type managers for Siemens PDM, Emerson AMS, and ABB 800xA. The EDD is on the USB stick shipped with the unit.

For PLC-side signal scaling, the PLC Analog Calculator and Modbus CRC Calculator handle the 4-20 mA to engineering-unit math and the CRC checking you may need when bridging the positioner into a Modbus RTU gateway on a Mitsubishi Q-series backplane.

Installation & Commissioning Tips

The 3730-2 is designed to be commissioned without proprietary tools. The integrated LCD and rotary pushbutton walk the installer through the auto-calibration sequence in roughly three minutes per valve. Practical tips from the field:

• Mechanical zero first. Before applying air, mechanically stroke the valve to its fail-safe position and set the positioner mounting so the non-contact sensor reads the start of travel within the sensor's working gap.
• Use the auto-tune wizard. From the LCD menu, run Init → Auto-Tune. The positioner ramps the actuator, learns the travel range, and stores the friction / dead-band coefficients automatically.
• Select the right characteristic curve. Linear, equal percentage, and quick-opening profiles are user-selectable — pick equal percentage for globe valves in throttling duty.
• Enable partial stroke test. For SIL service, schedule a PST interval (typically 6 or 12 months) and route the test result to the DCS so a stuck valve is flagged before a real demand arrives.
• Capture the valve signature. The on-board diagnostic logs hysteresis, seat load, and packing friction. A baseline signature at commissioning makes future trending meaningful.
• Keep a spare on the shelf. Plants running critical modulating duty often keep a Samson 3730-3 or Samson 3725 spare on hand. KOEED keeps both in stock alongside the 3730-2.

If you are upgrading from a conventional I/P positioner, the real-time sales list tracks recent shipments so you can see what other plants have paired the 3730-2 with.

Procurement, Warranty & Lead Time

KOEED is a multi-brand industrial automation sourcing specialist covering the nine core brands — Allen-Bradley, Siemens, Mitsubishi, Omron, Fanuc, Schneider, Yaskawa, Panasonic and KEYENCE — alongside adjacent process instrumentation categories such as Samson positioners, I/P converters, and control-valve assemblies. The 3730-2 ships from our Shenzhen / Hong Kong base with worldwide DHL / FedEx / UPS delivery and full export documentation.

• Lead time. In-stock catalog variants ship within 3 business days of PO. Special configuration (HART, FF, PROFIBUS) lead time confirmed at quote.
• Warranty. 12-month limited warranty against manufacturing defect, with extended options available for plant-wide service contracts.
• Authenticity. Sourced through established channels; serialized units ship with traceable documentation.
• BOM quotation. Send a full instrument list — positioners, valves, I/P converters, PLC I/O — and KOEED quotes the lot in one response.

For large orders or special variants (HART, FF, PROFIBUS, NEMA 4X stainless fittings), confirm configuration and lead time in writing with Moritta@KOEED.COM before issuing the purchase order.