Safety & Pressure Relief Valves

In operation, the pressure relief valve remains normally closed until pressures upstream reach the desired set pressure. The valve will then "crack" open to begin de-pressurising the system and continue to open further, allowing more flow as over pressure increases.-

In comparison, the two do serve different purposes, being the pressure relief valves often regulate overpressure with a gradual release, whereas safety relief valves are more of a sudden dump of overpressure from a pressure spike in the system. 

Varying sizes, pressure ranges, materials and approvals available on request.