Description
At-A-Glance Executive Brief
- Model: 38B5786X132
- Brand: Emerson Fisher
- Part Type: Relay C, Single-Acting Direct Pneumatic Relay
- Lifecycle status: Obsolete OEM, stocked new surplus and refurbished
- System compatibility: Fisher FIELDVUE DVC6200 digital valve controller
- Type: Single-acting, direct acting, standard bleed pneumatic relay
- Core function: Pneumatic power amplification, convert low pilot pressure signal to high-volume air output to drive single-acting valve actuator
Technical Introduction
The 38B5786X132 is the internal Relay C pneumatic amplifier assembly for Fisher DVC6200 FIELDVUE digital valve controllers. It takes low-pressure pilot air signal from the I/P converter and amplifies air volume to actuate single-acting spring return valve actuators. This relay provides fast pressure response and stable standard bleed design to eliminate valve hysteresis and dead band. It is a core wear component inside DVC6200 positioner, widely used on boiler feedwater, steam, and hydrocarbon control valves in power, chemical and refining plants.
Engineer’s Takeaway This is Relay C single-acting direct type, used only for single-acting spring return actuators. Not interchangeable with double-acting relay assemblies inside DVC6200. Common failure modes are blocked orifice, diaphragm fatigue, air leakage leading to valve hunting or slow stroke.
Core Technical Specifications
| Parameter | Value |
|---|---|
| Model | 38B5786X132 |
| Product Type | Pneumatic Relay C, Single-Acting Direct |
| Compatible Device | Fisher DVC6200 Digital Valve Controller |
| Output Pressure Range | 0.2 ~ 1.0 bar (3–15 psi) |
| Max Supply Pressure | 220.6 bar |
| Bleed Type | Standard bleed |
| Operating Temperature | -20℃ ~ +80℃ |
| Application | Single-acting spring return pneumatic valve actuator |
| Function | Pneumatic signal amplification, air volume boosting |
Please refer to the OEM datasheet for complete environmental tolerances.
Field Engineer’s Tech Notes
- Isolate valve, lock-out/tag-out and exhaust actuator air supply before opening positioner and replacing the relay.
- Instrument air quality is critical; water, oil and particulate contamination are primary causes of relay orifice clogging.
- After replacement, perform full valve stroke test, check for air leakage and verify valve stability to eliminate hunting.
- Confirm actuator type: this relay is for single-acting spring return actuators, cannot be used on double-acting actuators.
- Calibrate DVC6200 after relay replacement to re-establish 4-20mA input to valve stroke mapping.
Adaptive QA & Testing Protocol
Each unit undergoes bench pneumatic test. Supply pressure and pilot signal are applied to verify pressure amplification and stroke response. Leakage test checks diaphragm and seal integrity. Output pressure linearity and response speed are validated. Visual inspection checks for cracks, damaged diaphragms and blocked ports. Test reports and short validation videos are available upon request.
Buyer’s FAQ
Q: What valve controller uses 38B5786X132? A: It is the internal pneumatic Relay C assembly for Fisher DVC6200 FIELDVUE digital valve positioner, for single-acting spring return actuators.
Q: What warranty applies to new surplus or refurbished Emerson 38B5786X132? A: All units carry a 12-month hardware warranty. Warranty excludes damage caused by contaminated instrument air, improper installation, overpressure and diaphragm aging.
Q: Can this relay be used for double-acting actuator? A: No. This is single-acting direct relay C. DVC6200 double-acting version uses different relay assembly, not interchangeable.
Q: What lead time applies to this obsolete Fisher DVC6200 pneumatic relay? A: Stocked units ship within 1–3 working days. If out of stock, sourcing lead time can extend to 4–8 weeks subject to inventory availability.
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