Foxboro SRD991-BHNS1EA4NR-V01 Standard HART Valve Positioner | Single-acting Explosion-proof Position Controller

1. Product Overview

The Foxboro SRD991-BHNS1EA4NR-V01 is a standard single-acting intelligent HART valve positioner in the classic SRD991 product lineup. Different from dual I/O extended models, this version adopts a streamlined standard configuration, focusing on core valve positioning and basic HART intelligent monitoring functions, specially optimized for single-acting pneumatic actuators. It realizes precise closed-loop stroke control of linear and rotary process valves, serving as the core execution device for converting DCS 4–20mA control commands into pneumatic valve displacement actions.

This standard model features no built-in limit switches and no extended retransmission I/O, retaining core high-precision positioning and self-diagnosis capabilities. It is equipped with authoritative ATEX/IECEx intrinsic safety explosion-proof certification and IP65 industrial protection grade, matching standard M20 wiring interface and 1/4NPT pneumatic port. With SIL3 functional safety compliance and wide-temperature industrial adaptability, it delivers stable, cost-effective and low-failure operation for conventional valve regulation loops, widely applicable to mainstream process control scenarios in petrochemical, power and environmental protection industries.

2. Core Technical Parameters

• Product Type: Standard single-acting HART intelligent pneumatic valve positioner

• Applicable Actuator: Single-acting linear actuator (8–260mm stroke) / single-acting rotary actuator (0–95° swing angle)

• Control Input Signal: 4–20mA DC analog control signal + superimposed HART digital communication

• Extended I/O Function: No additional valve position retransmission and alarm switch output (standard basic version)

• Built-in Detection Switch: Without integrated limit switch structure

• Pneumatic Supply Pressure: 1.4–6.0bar standard industrial air source

• Positioning Accuracy: ±0.5% FS high linearity steady-state stroke control precision

• Safety Standard: IEC61508 certified SIL3 functional safety level

• Explosion-proof Grade: ATEX/IECEx Ex ia IIC T4 Gb intrinsic safety hazardous area certification

• Electrical Interface: Standard M20×1.5 single-port cable gland

• Pneumatic Interface: 1/4-18 NPT standard pneumatic manifold connection

• Human-machine Interface: Multi-language LCD display + physical button local operation

• Protection Grade: IP65 dustproof, waterproof and anti-corrosion sealed housing

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

3. Core Product Features

Positioned as a standard universal positioner for single-acting actuators, the SRD991-BHNS1EA4NR-V01 features streamlined and reliable design, cost-effective configuration and complete basic intelligent functions, forming a clear differentiation from extended high-end models:

• Exclusive Single-acting Actuator Matching Optimized internal pneumatic circuit and control algorithm are perfectly adapted to single-acting spring return pneumatic actuators. It accurately controls valve opening and closing strokes through positive air pressure regulation, ensuring stable spring reset response and no stroke jitter. It is the most matching standard positioning solution for conventional single-acting valve groups in process industries.

• Simplified Stable Standard Configuration Adopting a basic streamlined design without redundant extended I/O and limit switch structures, the internal mechanical and circuit structure is more concise. It effectively reduces potential failure points of components, lowers daily maintenance difficulty and failure rate, and provides ultra-stable long-cycle operation for conventional regulation loops with fixed control logic.

• Standard HART Intelligent Management & Diagnosis Retaining complete HART protocol functions, it supports remote parameter calibration, range adjustment, self-tuning and valve health diagnosis. It can monitor valve hysteresis, stiction and air source abnormal fluctuations in real time, helping engineers complete remote equipment management and hidden fault troubleshooting without on-site operation.

• High-standard Intrinsic Safety Protection Compliant with Ex ia IIC T4 high-grade intrinsic safety explosion-proof specifications, the low-power spark-proof circuit design eliminates ignition risks. It can be safely deployed in Zone 0/1/2 flammable and explosive hazardous areas, fully meeting safety production requirements of petrochemical and chemical high-risk workshops.

• SIL3 High-reliability Safety Operation Complying with international SIL3 functional safety standards, it maintains accurate and consistent execution of control commands under long-term full-load operation. It effectively reduces valve control failure probability, supports safety instrumented system linkage, and guarantees the safe and stable operation of process regulation loops.

• Easy Installation & Low Operating Cost Standard universal interface design is compatible with most industrial single-acting actuators and on-site wiring methods. The IP65 high-strength aluminum alloy sealed housing resists dust, moisture and mild corrosion, realizing long-term maintenance-free operation and reducing overall equipment operation and maintenance costs.

4. Industrial Application Scenarios

Foxboro SRD991-BHNS1EA4NR-V01 is widely used in conventional industrial valve regulation scenarios equipped with single-acting pneumatic actuators. It is mainly applied for routine flow and pressure regulation of petrochemical process pipeline valves, stable stroke control of thermal power plant auxiliary system water and gas valves, basic regulation loop control of fine chemical non-complex process valves, and standard intelligent transformation of traditional single-acting pneumatic valve groups. It is a high-cost-performance and high-reliability standard intelligent positioning device for general industrial process control systems.