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Constant Pressure Valve

Constant Flow Rate Valve
UFSJ type

Unique pilot mechanism provides excellent constant flow rate regulation

The unique pilot valve operation exhibits excellent constant flow characteristics.

Variable constant flow rate regulating function may be added for flow rate control over a wide range, allowing effective use and stable supply of water (optional).

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.

Constant Flow Rate Valve

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



Rated pressure



An orifice is provided at the inlet side of the valve, and differential pressure (P1-P1') that arises between the front and the rear of the orifice due to the flow rate fluctuation drives the pilot valve, thereby opening and closing the main valve and maintaining the set flow rate.


The pilot valve operates in the same manner as in the Constant Pressure Valve, with intermediate pressure Pe being formed by the actions of pilot A valve and pilot B valve. This intermediate pressure is transmitted to the top of the main valve for automatic adjustment of the main valve opening.


The set flow rate can be finely adjusted with the coil spring of the pilot valve. If flow rate control over a wide range is required, a butterfly valve or other flow rate adjustment valve (optional) may be installed in place of the fixed orifice.


Inlet pressure (Primary pressure)
Max. 1MPa (For JIS 10K standard)

Operating differential pressure
0.1MPa or more

Flow rate characteristics when the opening of the butterfly valve
(installed in place of the inlet side orifice) is adjusted
Constant Flow Rate Valve / Flow rate characteristics

Flow rate characteristics when the inlet pressure fluctuates
Constant Flow Rate Valve / Flow rate characteristics

Selection chart/Outer dimensions

Please refer to Common specifications & Outer dimensions.

If required bore size is 600mm or less, a direct-operation type constant flow regulator valve that operates without a pilot valve is also available and is generally more economical.
For details, please refer to Constant Flow Regulator Valve UF series.

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