Pressure relief valves (safety relief valves or safety valve) are made to open in a preset pressure and discharge fluid until the pressure drops to acceptable levels. The introduction of the security relief valve comes with an interesting history.

Denis Papin is credited by many people sources because the inventor from the first pressure relief valve (circa 1679) to avoid overpressure of his steam-powered "digester". His pressure relief design contained fat loss suspended on the lever arm. Once the pressure from the steam pressure functioning on the valve exceeded the pressure from the weight acting with the lever arm the valve opened up. Designs requiring a greater relief pressure setting needed an extended lever arm and/or bigger weights. This straightforward system labored however extra space was needed also it could easily be tampered with leading to the overpressure and explosion. Another disadvantage was premature opening from the valve when the device was exposed to bouncing movement.

Direct-acting deadweight pressure relief valves: Later to prevent the disadvantages from the lever arrangement, direct-acting deadweight pressure relief valves were placed on early steam locomotives. Within this design, weights were applied straight to the top valve mechanism. To help keep how big the weights inside a reasonable range, the valve size was frequently undersized producing a smaller sized vent opening than needed. Frequently a surge would occur because the steam pressure rose quicker than the vent could release excess pressure. Bouncing movements also prematurely released pressure.

Direct acting spring valves: Timothy Hackworth is thought to be the first one to use direct-acting spring valves (circa 1828) on his locomotive engine known as the Royal George. Timothy utilized an accordion arrangement of leaf springs, which may later get replaced with coil springs, to use pressure towards the valve. The spring pressure might be fine-tuned by modifying the nuts retaining the leaf springs.

Refinements towards the direct acting spring relief valve design ongoing in subsequent years as a result of the prevalent utilization of steam boilers to supply heat and also to power locomotives, river motorboats, and pumps. Steam boilers are less frequent today however the safety relief valve remains a vital component, in systems with pressure vessels, to safeguard against damage or catastrophic failure.

Each application features its own unique needs but prior to getting into the buying process, let?¡¥s take a look at the operating concepts of the direct acting pressure relief valve (PRV).