The Fig. 573 Pressure Sustaining Valve is single seated, piston assisted and spring regulated.

The system pressure being relieved acts upon the piston and provides control of the valve opening in accordance with the regulating spring setting.

A better control of pressure and flow is provided for installations where a direct spring loaded type is too insensitive.

Protects systems from overpressure

Monitors pump outputs

For water, air, gas, oil or chemical services.