Foxboro SRI990 Modular Analog Valve Positioner | Switch-configurable Single/Double Acting Controller

1. Product Overview

The Foxboro SRI990 is an upgraded modular analog electro-pneumatic valve positioner, serving as an enhanced iteration of the classic SRI986 series. As a non-HART, pure analog positioning device, it abandons complex digital intelligent functions and focuses on higher versatility and flexible on-site configuration. The biggest differentiation lies in its universal actuator compatibility, supporting both single-acting and double-acting pneumatic actuators via simple DIP switch adjustment, unlike the single-acting-only limitation of conventional analog positioners.

Adopting a detachable modular electronic and pneumatic structure, the SRI990 supports on-site mode switching and functional expansion without replacing the whole unit. It features ultra-low steady-state air consumption, adjustable positive/reverse action and split-range control, paired with optional 4–20mA valve position retransmission output. Complying with NAMUR and IEC industrial mounting standards and equipped with intrinsic safety explosion-proof certification, it delivers stronger scene adaptability and upgrade scalability than traditional analog models, ideal for traditional analog control system transformation and multi-type valve group unified matching.

2. Core Technical Parameters

• Product Type: Modular universal pure analog electro-pneumatic positioner (non-digital, non-HART)

• Applicable Actuator: Switch configurable for single-acting / double-acting linear and rotary actuators

• Input Signal: Standard 4–20mA DC analog control signal

• Loop Load: 300Ω maximum load resistance for 4–20mA current loop

• Supply Air Pressure: 1.4–6.0bar standard air supply; max 7.0bar with optional spool valve

• Air Consumption: <0.05Nm³/h ultra-low steady-state air consumption

• Configuration Mode: DIP switch action setting + potentiometer zero/span fine tuning

• Control Function: Forward/reverse action switching + multi-stage split-range control

• Extended Output: Optional isolated 4–20mA valve position feedback signal

• Explosion-proof Grade: ATEX/IECEx intrinsic safety explosion-proof for hazardous areas

• Mounting Standard: NAMUR IEC 534-6 linear actuator / VDI/VDE 3845 rotary actuator compliant

• Protection Grade: IP65 industrial dustproof and waterproof sealed housing

• Working Temperature: -40°C ~ +80°C wide industrial temperature range

• Structural Feature: Modular detachable design, support on-site electronic module upgrade

3. Core Product Features

Compared with fixed single-acting SRI986 and fully digital SRD series positioners, the SRI990 balances simplicity and flexibility, with unique universal matching and modular upgrade advantages:

• Universal Single/Double Acting Switch Compatibility Breaking the limitation of traditional analog positioners that can only match single-acting actuators, this model realizes free switching between single-acting and double-acting control modes via internal DIP switches. It covers linear and rotary valve types in one unit, unifying spare part models for on-site valve groups and greatly simplifying engineering selection and inventory management.

• DIP Switch Fast Configuration + Precision Mechanical Tuning It adopts dual debugging mode: basic control logic such as forward/reverse action and signal range is set by quick DIP switches, while zero point, span and loop gain are precisely calibrated by high-precision potentiometers. The combination of fast switching and fine tuning improves on-site commissioning efficiency while ensuring positioning accuracy.

• Ultra-low Energy Consumption & Stable Operation Optimized pneumatic circuit structure achieves extremely low static air consumption, effectively reducing long-term plant air supply load. The pure analog circuit eliminates digital jitter and program crash risks, maintaining stable and consistent positioning output in complex electromagnetic interference environments, with higher operational stability than intelligent models.

• Modular On-site Upgrade Scalability The split electronic and pneumatic modular structure supports independent replacement and upgrade of core components. Users can expand valve position feedback function or adjust control characteristics on site without disassembling the whole positioner and changing mounting brackets, reserving transformation space for subsequent system upgrades.

• Optional Isolated Position Retransmission Equipped with optional isolated 4–20mA position feedback module, it realizes real-time valve stroke signal upload to DCS system without external auxiliary transmitters. The integrated design simplifies on-site wiring, reduces intermediate signal links, and improves the reliability of valve status monitoring.

• Hazardous Area High-reliability Adaptation Certified with intrinsic safety explosion-proof grade, it can be safely deployed in Zone 1/2 flammable and explosive industrial sites. IP65 fully sealed housing resists dust, moisture and mild corrosive gas, adapting to long-term 24/7 unattended operation of process valves.

4. Industrial Application Scenarios

Foxboro SRI990 is widely used in traditional analog control industrial scenarios requiring mixed matching of single/double-acting valve groups. It is mainly applied for unified positioning control of mixed valve types in petrochemical process workshops, stable regulation of auxiliary system valves in thermal power plants, split-range linkage control of fluid valves in fine chemical and pharmaceutical industries, and replacement and upgrading of old SRI986 fixed-type positioners. It is a high-versatility, low-energy-consumption and easy-maintenance universal analog valve positioning solution for traditional industrial automation systems.