The Fisher-Rosemount W38077 (Flow Control-2) is a specialized printed circuit board designed for precision signal processing and feedback loop management within industrial flow control valves and pneumatic actuators.
Product Parameters (Datasheet)
- Model Number: W38077
- Part Name: PCB Flow Control-2
- Manufacturer: Fisher-Rosemount (now Emerson Automation Solutions)
- Board Type: Multi-layer Analog/Digital Control PCB
- Signal Input: 4-20mA DC (Standard Control Signal)
- Supply Voltage: 24V DC nominal (derived from positioner or controller base)
- Feedback Interface: Potentiometric or Hall-effect position feedback compatibility
- Output: PWM or analog drive signals for I/P converters and solenoid pilots
- Calibration: On-board zero and span adjustment potentiometers
- Environmental Coating: Conformal coating for protection against moisture and chemical vapors
Country of Origin
This precision electronic component was manufactured by Fisher Controls (Emerson) in the United States, specifically designed for use in their global fleet of high-performance valve positioners and controllers.
Application Fields
The W38077 board is a critical sub-assembly used in demanding fluid regulation environments:
- Oil & Gas: Controlling the flow of crude oil and natural gas in separator vessels and pipelines.
- Chemical Processing: Managing precise dosing of reagents in high-pressure reactor loops.
- Power Generation: Regulating feedwater and steam flow in boiler control systems.
- Refining: Operating large-scale control valves in hydrocracking and distillation units.
Product Usage Instructions
- ESD Safety: Always wear an anti-static wrist strap when handling the W38077 to prevent damage to the high-sensitivity CMOS components.
- Installation: Power down the valve positioner. Carefully align the W38077 with the internal mounting standoffs and secure the board using the original non-conductive screws.
- Wiring: Reconnect the ribbon cables or terminal headers, ensuring all pins are straight and fully seated. Verify the polarity of the loop-power input.
- Calibration: Once installed, perform a “Stroke Calibration.” Adjust the on-board zero and span pots until the valve travel perfectly matches the 4-20mA input signal.
- Sealing: Ensure the positioner housing cover is properly gasketed after installation to maintain the board’s protection against the external environment.
Product Technical Description
The W38077 Flow Control-2 board functions as the “brain” of a valve positioner. Technically, it performs a continuous comparison between the “Command” signal (from the DCS) and the “Actual” position signal (from the valve stem). It utilizes high-precision operational amplifiers to calculate the error signal and generates a corrected output to the I/P (current-to-pressure) transducer. This board is engineered for high vibration resistance, allowing it to remain accurate even when mounted directly on large, vibrating control valves.
Q&A (Common Questions)
Q: Can I use the W38077 in a hazardous (Ex) area? A: The board itself is designed to be housed within an explosion-proof or intrinsically safe positioner enclosure (like the Fisher DVC series). Always check the certification of the overall assembly.
Q: What are the symptoms of a failing W38077 board? A: Common signs include “hunting” (the valve constantly moving back and forth), failure to reach the full open/closed position, or a total lack of response to the 4-20mA signal.
Q: Is this board compatible with HART communication? A: This specific legacy model is primarily an analog control board. For HART digital diagnostics, a newer generation DVC6000 or DVC6200 series digital valve controller would be required.
Q: Can I clean the board if it gets oily? A: You may use electronic-grade isopropyl alcohol and a soft brush, but ensure the board is completely dry before re-applying power.
Similar Model Recommendations
- Fisher W38078 (Alternative revision for different valve sizes)
- Fisher 3582i (Complete electro-pneumatic positioner)
- Fisher DVC6200 (Modern digital successor board)
- Fisher 546 (I/P Transducer companion)
- Fisher 3610J (Pneumatic positioner assembly)
For more information on the Fisher-Rosemount W38077 and other genuine Fisher valve parts, please contact our technical sales team.
