Safety Valve, Pressure Relief Valve

Safety Valve, Pressure Relief Valve
UFSS type
(PAT.), UFSA type (PAT.)

Rapid prevention of excessive increase of inlet pressure

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UFSS type (Safety Valve):

Prevents inlet pressure from excessive rising

UFSA type (Pressure Relief Valve):

Maintains inlet pressure at the set pressure

The excellent pilot valve mechanism provides rapid response under any condition and prevents inlet pressure from rising.

The unique closure mechanism maintains complete water shutoff in the fully closed condition.

The pilot valve does not have any minute, fixed restriction passage like a needle valve, and is therefore clog-resistant.
And, even if clogging by foreign material occurs, the built-in self-cleaning mechanism causes the clogged valve part to open automatically to remove the foreign material.

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

Pressure Relief (Safety) Valve

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



Rated pressure



When inlet pressure (primary pressure) P1 rises above the set pressure, the pilot valve operates and the main valve is opened to release the excess pressure to the outlet side and maintain the inlet pressure at the set pressure.


Under normal conditions, pilot A valve is open and pilot B valve is closed so that inlet pressure P1 is transmitted to the top of the main valve to keep the main valve closed.
When inlet pressure P1 exceeds the set pressure, pilot A valve closes and pilot B valve opens to reduce the pressure acting on the top of the main valve, thus opening the main valve and preventing the inlet pressure from rising.


The set pressure can be finely adjusted with the coil spring of the pilot valve.


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

Operating differential pressure
50kPa or more

Pressure Relief (Safety) Valve /  Flow rate characteristics

Example applications

Pressure Relief (Safety) Valve / Examples of applications

Pressure Relief (Safety) Valve /  UFSS-200

Water Purification Project Cooperative in Kagoshima Pref.


Selection chart/Outer dimensions

Please refer to Common specifications & Outer dimensions.

Technical data
Selection & Dimensions
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