The Fig 163 Type ‘MF’ Pressure Sustaining/Relief Valve is a hydraulically operated, single-seated valve that is piston actuated, pilot controlled, and spring regulated.

It maintains a constant upstream set pressure, protects against pipeline surges, capable of fast opening and slow closing, and helps stabilise pump output.

The pilot valve senses upstream pressure, venting the piston when setting is exceeded, thereby opening the main valve. When set pressure is restored, the pilot closes, thereby applying line pressure to the piston to close the valve at the rate determined by the flow restrictor. The ‘V-Ported’ valve guide eliminates closing surges. In operation the valve can maintain a modulating function.