Product Overview
The FOXBORO SRI986-BIDS7ZZZNA is an Electro-Pneumatic Positioner, a critical instrument used in industrial automation to accurately control the position of pneumatic valve actuators. Manufactured by Foxboro (now part of Schneider Electric), this specific model is designed for single-acting pneumatic actuators. Its primary function is to convert an electrical control signal (typically a 4-20 mA current signal from a DCS or PLC) into a precise pneumatic output pressure that drives the valve to a desired position.
The SRI986-BIDS7ZZZNA plays a crucial role in closed-loop control systems, enhancing the performance of control valves. It continuously compares the actual valve position (sensed by its internal feedback mechanism) with the commanded position (from the electrical input signal) and adjusts the air pressure to the actuator accordingly. This feedback control allows the positioner to overcome issues like valve friction, varying process forces, and supply air pressure fluctuations, ensuring high accuracy, faster response times, and improved stability of the control loop. The “BIDS7ZZZNA” in the model code deciphers specific configurations: “B” for single-acting, “I” for 4-20 mA input, “D” for direct action (increasing input increases output), “S” for no built-in limit switches/position transmitter, “7” for M20 cable entry, and “ZZZNA” for specific certifications and attachment kit/manifold auxiliary ordering.
Technical Specifications
Main Features and Advantages
The FOXBORO SRI986-BIDS7ZZZNA Electro-Pneumatic Positioner boasts a range of features and advantages that make it a highly effective and reliable choice for precise valve control in industrial processes.
High Positioning Accuracy and Stability: The core strength of the SRI986-BIDS7ZZZNA lies in its ability to precisely position pneumatic valve actuators. By continuously comparing the electrical input signal with the actual valve position and adjusting the pneumatic output, it significantly reduces hysteresis, dead band, and friction effects. This results in superior control accuracy, stable valve positioning, and improved process control performance.
Robust and Durable Design: Engineered for harsh industrial environments, the FOXBORO SRI986-BIDS7ZZZNA is built with rugged materials and a robust construction that can withstand wide temperature fluctuations (-40°C to +80°C), vibrations, and challenging atmospheric conditions. This durability ensures long-term reliability and consistent performance in demanding applications.
Versatile Input Signal Compatibility: The positioner accepts a standard 4-20 mA electrical input signal, making it highly compatible with a wide range of modern control systems such as Distributed Control Systems (DCS) and Programmable Logic Controllers (PLC). This common input standard simplifies integration into existing and new automation architectures.
Independent Adjustment Capabilities: The SRI986-BIDS7ZZZNA offers independent adjustment of stroke range and zero point, along with adjustable amplification and damping. This flexibility allows for fine-tuning the positioner’s response to match the specific characteristics of the valve and the dynamic requirements of the process, optimizing control loop performance.
NAMUR Standard Mounting: The positioner adheres to IEC 534, Part 6 (NAMUR) mounting standards, facilitating easy and standardized installation on a wide variety of pneumatic valve actuators, whether they are linear (diaphragm) or rotary actuators (with an adapter).
Low Air Consumption: Despite its powerful control capabilities, the FOXBORO SRI986-BIDS7ZZZNA is designed for efficient air consumption, contributing to lower operational costs and reduced strain on plant air systems.
Application Field
The FOXBORO SRI986-BIDS7ZZZNA Electro-Pneumatic Positioner is widely deployed across various industrial sectors where precise and reliable control of pneumatic valves is critical for process efficiency, safety, and product quality.
Chemical and Petrochemical Industry: In chemical processing plants, the SRI986-BIDS7ZZZNA is essential for accurately controlling flow rates, pressures, and temperatures by precisely manipulating control valves in reactors, distillation columns, and blending operations. Its ability to handle corrosive environments (when specified) and provide tight control is highly valued.
Oil and Gas Production and Refining: From upstream wellhead control to midstream pipeline operations and downstream refining processes, the FOXBORO SRI986-BIDS7ZZZNA is used on critical control valves for regulating oil, gas, and steam flows, ensuring optimal throughput and preventing hazardous conditions.
Power Generation: In power plants (fossil fuel, nuclear, and renewable), these positioners control steam and water flows, manage turbine bypass valves, and regulate combustion air, contributing to efficient energy production and stable grid operation.
Water and Wastewater Treatment: The SRI986-BIDS7ZZZNA is applied in municipal and industrial water treatment facilities to control flows through filtration systems, chemical dosing, and aeration processes, ensuring water quality and efficient plant operation.
Pulp and Paper Industry: In pulp and paper manufacturing, the positioner controls various valves regulating steam, chemicals, and stock flows, optimizing production processes and ensuring product consistency.
Food and Beverage Industry: For applications requiring precise temperature or flow control in mixing, heating, or cooling stages, the FOXBORO SRI986-BIDS7ZZZNA provides the necessary accuracy for consistent product quality and efficient production.
Essentially, any industrial process that relies on pneumatic control valves for modulating flow, pressure, level, or temperature will benefit from the precision and reliability offered by the FOXBORO SRI986-BIDS7ZZZNA positioner.
Related Products
The FOXBORO SRI986-BIDS7ZZZNA Electro-Pneumatic Positioner is part of a larger ecosystem of process instrumentation and control systems. Related products typically include:
Control Valves and Actuators: The SRI986-BIDS7ZZZNA is designed to directly mount onto and control single-acting pneumatic valve actuators (diaphragm or piston types) from various manufacturers, which are then integrated with a control valve body.
Control Systems (DCS/PLC):
- Foxboro (Schneider Electric) I/A Series DCS / Foxboro Evo™ Process Automation System: These are the primary distributed control systems that would provide the 4-20 mA input signal to the SRI986-BIDS7ZZZNA.
- Other PLCs or DCSs: Any industrial control system capable of outputting a 4-20 mA analog control signal.
Instrumentation and Sensing Devices:
- Process Transmitters: (e.g., pressure, temperature, flow, level transmitters) that provide feedback signals to the DCS/PLC, allowing the control system to generate the 4-20 mA command signal for the SRI986-BIDS7ZZZNA.
- Limit Switches / Position Transmitters: While the “-S” in this model indicates “without” built-in switches/transmitters, these are often added as auxiliary equipment to the positioner or valve for remote indication of valve open/closed status or actual position feedback. The Foxboro SRI986 series supports modular addition of these.
Air Supply and Conditioning Equipment:
- Filter Regulators: (e.g., FRS02) Essential for providing clean, dry, and regulated air pressure to the SRI986-BIDS7ZZZNA, as air quality significantly impacts positioner performance and longevity.
- Air Boosters/Volume Boosters: Used with the positioner to increase the speed of large valve actuators by increasing the air flow capacity.
- Connection Manifolds: Often used for pneumatic connections, which the “A” in the model code (Manifold: Order as Auxiliary) refers to.
Smart Positioners (Alternative/Advanced):
- Foxboro SRD991, SRD998, or SRI990: These are “smart” or “digital” positioners from Foxboro/Eckardt that offer enhanced diagnostics, HART communication, and auto-calibration features, representing an advancement over the purely analog SRI986.
Installation and Maintenance
Pre-installation preparation: Before installing the FOXBORO SRI986-BIDS7ZZZNA Electro-Pneumatic Positioner, ensure that the pneumatic valve actuator is properly mounted and in good working condition. Verify that a clean, dry, and regulated instrument air supply (within the specified 1.4 to 6 bar range) is available at the installation point. Ensure the 4-20 mA electrical control signal from the DCS or PLC is properly wired and isolated. Have the appropriate mounting kit (e.g., NAMUR compliant bracket, coupling lever) for your specific valve actuator readily available, as the SRI986-BIDS7ZZZNA model code implies the attachment kit is ordered as an auxiliary. Always refer to the detailed installation manual (PSS EVE0102 A) provided by Schneider Electric/Foxboro for specific mounting instructions, pneumatic connections, and electrical wiring diagrams to ensure correct installation and optimal performance.
Maintenance recommendations: The FOXBORO SRI986-BIDS7ZZZNA is designed for robust and reliable operation, but regular maintenance ensures its longevity and accurate performance.
- Regular Visual Inspection: Periodically check the positioner for any signs of physical damage, corrosion, air leaks from pneumatic connections, or loose electrical terminals.
- Air Supply Quality: Ensure the instrument air supply remains clean and dry. Clogged air filters or contaminated air can lead to positioner malfunction. Replace air filters as recommended by the filter regulator manufacturer.
- Calibration Check: While the SRI986 is an analog positioner, periodic calibration checks (e.g., annual) are recommended to ensure its accuracy. This involves applying known input signals and verifying the corresponding valve position, making adjustments to the zero and span if necessary using the accessible adjustment screws.
- Damping and Amplification Adjustment: If process oscillations or sluggish valve response are observed, the adjustable damping and amplification can be fine-tuned to optimize control loop performance.
- Troubleshooting: Consult the product manual for troubleshooting steps if the positioner exhibits erratic behavior, fails to respond, or shows excessive deviation. Common issues often relate to air supply problems, feedback mechanism issues, or electrical signal integrity.
