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Pressure Sustaining Valve

Pressure Sustaining Valve
UFSC type

Excellent inlet pressure control and rapid shutoff performance

During water supply, the excellent pilot valve mechanism provides rapid response under any condition and maintains constant inlet pressure. And when water supply is stopped, the valve closes immediately and completely, sustaining the back-pressure (inlet pressure), and thereby preventing water-hammer at restart of the water supply.
This valve is most suitable for applications such as controlling and sustaining back-pressure in a chilled/hot water circulation system (open circuit method) for air-conditioning.

The pilot valve does not have any minute, fixed restriction passage like a needle valve, and is therefore clog-resistant.

Due to its simple construction, troublesome adjustments are unnecessary. Being excellent in durability and practically maintenance-free, using this valve reduces maintenance costs.

Pressure Sustaining Valve

Patented in Japan, U.S.A., other



Rated pressure



During water supply, pilot A valve and pilot B valve operate in the same manner as in the Pressure Relief Valve to form intermediate pressure Pe, which is transmitted to the top of the main valve for automatic adjustment of the main valve opening, maintaining inlet pressure (primary pressure) P1 at the set pressure.
In this period, pilot C valve is closed, not affecting operation of pilot A valve and pilot B valve.


When water supply is stopped and inlet pressure P1 begins to drop, pilot A valve opens, pilot B valve closes, and inlet pressure P1 is applied to the top of the main valve. At that moment, inlet pressure P1 is also applied to the top of the main valve through opened pilot C valve that acts as an accelerator for main valve closure. Thus the main valve closes immediately and completely, preventing water on the inlet side from draining off, thereby sustaining the inlet pressure P1.


The set pressure can be finely adjusted with the coil springs of the pilot valves.


Inlet pressure (Primary pressure)
Max. 0.7MPa (For JIS 10K standard)

Operating differential pressure
50kPa or more

Pressure Sustaining Valve

Example application

Pressure Sustaining Valve

Selection chart/Outer dimensions

Please refer to Common specifications & Outer dimensions.

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