Spirax Sarco SP7 Smart Valve Positioner HART Fieldbus for Industrial Steam Valves

Product Overview

The Spirax Sarco SP7 is a smart electro-pneumatic valve positioner that can be configured electronically. It mounts on pneumatic linear or rotary actuators that follow the NAMUR standard. The unit ensures that valve stroke and the incoming mA signal remain exactly proportional.

The SP7-1* uses a cast aluminium housing treated for outdoor service. It fits actuators with rotary travel from -57 to +57° or linear travel from -28 to +28°. A mounting kit and pressure gauge block can be supplied as options. Control signal is in mA, and supply air pressure ranges from 1.4 to 6 bar. The positioner can also reverse the control signal action.

The SP7-10 comes with a local communication interface (LCI) as standard. An optional HART module allows communication over the 20mA signal. HART 5 or HART 7 are available. The SP7-11 uses PROFIBUS PA, and the SP7-12 uses FOUNDATION Fieldbus. A digital input can trigger control system functions, while a digital output sends collective alarm or fault messages. The SP7 is one of the most energy-efficient positioners on the market, with maximum steady-state air consumption of 0.015 SCFM — up to 50 times better than similar electro-pneumatic positioners.

Technical Specifications

Application Industry

The SP7 is used in steam control systems, process heating and cooling, food and beverage utilities, pharmaceutical clean steam, and general industrial valve control. It suits applications where reliable digital positioning and low energy use are important. The positioner works with any NAMUR-conforming actuator, including Spirax Sarco BVA300, PN1600, PNS3000, PNS4000, PN9000, and TN2000 series.

Common Problems

• Positioner does not respond to input signal: Check supply air pressure is within 1.4~6 bar. Verify pneumatic connections are secure. Confirm air quality meets ISO 8573-1:2010 Class 3:3:3.

• Valve position does not match input signal: Check the characteristic curve setting. Verify that the operating direction is correctly set. Recalibrate the zero point.

• Slow valve response: Check supply air pressure and filter. Verify the air supply tube is not restricted.

• ERROR 10 (Power supply interrupted): The power supply was interrupted for at least 20 ms. The actuator moves to the safe position. After approx. 5 seconds, the positioner resets automatically.

• ERROR 11 (RAM error): The actuator moves to the safe position. After approx. 5 seconds, the positioner resets and the RAM is reinitialized.

• SENS_ERR (Position sensor defective): The position sensor is defective. Contact service for replacement.

• ALARM 1 (Leakage between positioner and actuator): Check pneumatic tubing and fittings for leaks.

• ALARM 2 (Setpoint current out of range): Check the input signal source and wiring.

Replacement Models

The Spirax Sarco SP7 is a current-generation smart positioner platform. The SP8 Smart Positioner is the next-tier option from the same product line, offering advanced valve diagnostics with long-term data trending to benchmark current valve performance against a new control valve. For legacy installations, the SP7 serves as an upgrade from older Spirax Sarco EP5/EP6 series positioners and pneumatic-only positioners. For cross-vendor alternatives, verify actuator mounting, travel range, and communication protocol before ordering.