Core Technical Advantages
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Integrated Fail-Safe Logic: Unlike older systems that require three separate switching valves, a single Fisher 377 can be configured for any of the three primary fail modes. This reduces hardware costs, simplifies piping, and significantly lowers the number of potential leak points in your system.
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Universal Fail-Mode Conversion: The same valve body can be used for Fail-Up, Fail-Down, or Lock-in-Last-Position. Switching between these modes only requires minor changes to the external tubing hook-ups, allowing you to standardize on one part for multiple applications.
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Precision Trip Point: The trip point is fully adjustable, allowing you to set the exact pressure at which the safety action triggers. This ensures your valve only trips when the supply is truly compromised, preventing nuisance trips during minor pressure dips.
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High-Efficiency Internals: The 377 utilizes large diaphragm areas and a minimalist few moving parts design. This ensures the valve reacts instantly with high force when the trip point is hit, while also extending service life and reducing maintenance requirements.
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Automatic Reset: Once supply pressure rises back above the trip point (plus a small deadband to prevent chatter), the 377 automatically resets, returning the actuator to normal control without manual intervention.
Technical Core
| Feature | Technical Specification / Detail |
| Fail Modes | Fail Up, Fail Down, or Lock-in-Last-Position |
| Trip Point Range | Adjustable from 1.4 to 4.1 bar (20 to 60 psig) |
| Max Supply Pressure | 10.3 bar (150 psig) |
| Flow Capacity | High-flow ports to ensure rapid actuator response |
| Temperature Limits | Standard: -40 to 82°C (-40 to 180°F) |
| Construction | Aluminum or Stainless Steel housing options |
| Media | Air or Sweet Natural Gas |
Applications and Industry Sectors
The 377 is a standard specification for any control loop where a safe state is required during a power or air failure.
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Oil and Gas Production: Ensuring that emergency shutdown (ESD) valves close or lock in place if a compressor or air header fails.
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Refining and Chemical: Protecting high-value process reactors by forcing control valves to a specific safety position to prevent overpressure or thermal runaway.
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Power Generation: Managing steam or water supply lines where a loss of control signal could lead to turbine damage.
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Remote Pipelines: Utilizing its automatic reset capability to restore normal operations at unmanned stations once pressure is restored.
Xi’an Yunrui Trading Co., Ltd. Technical Support
Xi’an Yunrui Trading Co., Ltd. is a major supplier of Fisher brand products. We specialize in providing original, high-efficiency Emerson automation solutions to industrial clients. Beyond supplying core hardware like the 377 Trip Valve, we leverage deep technical expertise to provide professional support and model selection guidance for procurement and engineering projects. By optimizing our supply chain, we provide a distinct pricing advantage, ensuring we offer highly competitive prices while assisting clients in optimizing processes and achieving digital upgrades.
If you are currently designing a fail-safe loop and need to verify the piping schematic for a Lock-in-Last-Position configuration, or if you need to source NACE-compliant versions for sour gas service, please contact our technical team.
