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Constant Pressure Valve

Constant Pressure Valve
UFSP type

Excellent pressure control and complete liquid shutoff performance

With both opening and closing valve parts being aligned along a single axis, the pilot valve performs excellent pressure control under any condition.

The unique closure mechanism realizes complete water shutoff performance. The set outlet pressure is maintained even in the fully closed condition, therefore costs for pipes on the downstream side of the valve can be reduced.

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 Pressure Valve

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



Rated pressure



Intermediate pressure Pe, between inlet pressure (primary pressure) P1 and outlet pressure (secondary pressure) P2, is formed inside the pilot valve and is transmitted to the top of the main valve to maintain an appropriate main valve opening.


When the usage amount at the outlet side decreases and outlet pressure P2 rises above the set pressure, pilot A valve opens and pilot B valve closes to raise intermediate pressure Pe. This causes the main valve to become restricted and the outlet pressure to be reduced to the set pressure.
Conversely, when the usage amount at the outlet side increases and outlet pressure P2 drops below the set pressure, pilot A valve closes and pilot B valve opens to reduce intermediate pressure Pe. This causes the main valve to open and the outlet pressure to be raised to the set pressure.


With the same mechanism, the pilot valve responds to fluctuation of the inlet pressure, thereby automatically adjusting the main valve opening appropriately and maintaining the outlet pressure at the set pressure.


In the fully closed condition, pilot B valve is closed completely by the outlet pressure and, at the same time, the inlet pressure is received effectively by the top of the main valve. The main valve is therefore shut firmly and the inlet and the outlet sides are shut off completely.


The set pressure can be finely adjusted with the coil spring of the pilot valve.
If the main valve, pilot A valve, or pilot B valve becomes clogged by foreign material, the clogged valve opens in response to the change of pressure due to clogging and automatically removes the foreign material.


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

Outlet pressure (Secondary pressure)
50kPa or more

Pilot Valve type
2nd pressure is Max. 0.7MPa : PLV (diaphragm type)
2nd pressure is more than 0.7MPa : PLV-H (piston type)

Set pressure adjustment range
+/- 70kPa

Operating differential pressure
50kPa or more

Pressure control characteristics under operation of the downstream side terminal valve
Constant Pressure Valve / Pressure control characteristics

Example applications

Gravity flow system
Constant Pressure Valve / Gravity flow system

Pump feeding system
Constant Pressure Valve / Pump feeding system

Constant Pressure Valve / UFSP-150
Hidaka-gun Nanbugawa River District
Irrigation in Wakayama Pref.

Constant Pressure Valve / UFSP-100
Uwaba Agricultural Irrigation Office
in Saga Pref.

Selection chart/Outer dimensions

Please refer to Common specifications & Outer dimensions.

Constant Pressure Valve with over-discharge cutoff function is also available.
For details, please refer to this page.

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