Pressure Relief / Sustaining

Pressure relief and pressure sustaining valves for water systems are used in distribution networks, pumping stations, reservoirs, pressure zones and pipelines with variable demand, where overpressure protection or minimum upstream pressure control is required. The category includes CSA XLC hydraulically operated automatic control valves, CSA VSM direct-acting valves.

XLC valves operate through a pilot-controlled hydraulic circuit and are configured according to the required function: pressure sustaining, pressure relief, or combined pressure reducing and sustaining control. They may be installed on the main line or on a bypass line, depending on the system layout and the required discharge capacity. Typical applications include protection of pipelines, pumps, instruments and downstream equipment against excessive pressure, as well as maintaining stable upstream pressure in elevated zones, secondary branches or critical supply lines.

Available configurations cover PN 10, PN 16, PN 25 and PN 40 pressure classes, with EN 1092-2 flanged or BSP connections, DIN face-to-face dimensions and construction materials such as ductile cast iron GJS 450-10, stainless steel internal components, stainless steel pilot tubing, stainless steel seat and epoxy coating. CSA XLC valves are designed and tested according to EN 1074, with typical sizes from DN 50 to DN 400 and service temperature for treated water up to 70°C, with special versions available for higher temperatures where required.

Valve selection should be based on set pressure, available differential pressure, required relief flow, cavitation risk, transient response, connection type and maintenance accessibility. In systems exposed to rapid pressure rise or water hammer, dedicated surge relief valves should be considered. For compact installations or higher temperature operation, direct-acting VSM or VSM ST versions may be selected depending on pressure range, medium compatibility and installation conditions.