Core Technical Advantages
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Fast, Positive Switching Action: The internal snap-acting mechanism ensures that the valve shifts completely and rapidly. This prevents “throttling” or hovering in an intermediate state, which is critical for the reliable operation of downstream pneumatic components like actuators or relays.
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Full Adjustability: Both the upper and lower switching limits can be precisely adjusted. This allows the valve to be tailored to specific process pressures, ensuring it trips exactly when needed without premature firing due to minor signal noise.
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Versatile Three-Way or On/Off Action: These valves can be piped for either three-way operation (diverting flow between two different ports) or standard two-way on/off action. This flexibility allows a single valve model to handle various logic functions across a plant.
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Automatic or Manual Reset: Depending on the specific safety requirements of your loop, these valves can be configured to reset automatically once the signal pressure returns to normal, or require a manual reset by an operator to ensure the process is safe before restarting.
Technical Core
| Feature | Technical Specification / Detail |
| Action Type | Snap-acting (Non-throttling) |
| Input Signal | Pneumatic pressure signal |
| Service Media | Air or non-corrosive gas |
| Port Configurations | 3-Way (Standard) or 2-Way (On/Off) |
| Reset Options | Automatic or Manual |
| Maximum Inlet Pressure | Varies by model (up to 10.3 bar / 150 psig typical) |
| Temperature Limits | -40 to 71°C (-40 to 160°F) |
Applications and Industry Sectors
The 168 series is primarily used in pneumatic control loops that require “if/then” logic without the need for electronic controllers.
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Oil and Gas: Functioning as high/low pressure sensors in wellhead safety systems to shut in a well if line pressure deviates.
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Chemical Processing: Acting as a pneumatic interlock to prevent the opening of a process valve unless a specific pressure condition is met.
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Power Generation: Managing pneumatic sequencing for soot blowers or auxiliary cooling systems.
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General Manufacturing: Controlling the “start/stop” logic for pneumatic motor-driven equipment and conveyor systems.
Xi’an Yunrui Trading Co., Ltd. Technical Support
Xi’an Yunrui Trading Co., Ltd. is a major Fisher Valves supplier, providing a comprehensive range of Fisher solutions. We specialize in providing original, high-efficiency Emerson automation solutions to industrial clients. Beyond supplying core hardware like the 168 Series Switching 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 pneumatic logic circuit and need to verify the deadband (differential) between the trip and reset points for the 168H, please contact our technical team for a calibration sheet.
