Pressure relief valves
The 50 series pressure relief valve is designed to maintain a constant pressure upstream within tight limits. Once in operation, the valve is actuated by the line pressure through a pilot control system that opens quickly to maintain a stable line pressure, but closes gradually to avoid sharp increases in pressure.

In addition to the relief of sudden increases in pressure, this valve can be used for pressure relief, pressure maintenance, back pressure or discharge functions in a bypass system.

Pressure relief and safety valves

Discharge the excess pressurization to protect the downstream equipment or control the upstream pressure of gas or liquid.

Proportional pressure relief valves


  • Simple and reliable protection against excessive pressure in a variety of general industrial applications
  • Easy external adjustment of firing pressure
  • Available for high and low pressure

Pressure relief valve cla val

Pressure relief valve cla val are specifically designed for fire protection pumping systems and are available in a variety of configurations and end connections.

  • The 50 series pump pressure relief and suction control control valves used in conjunction with fire pumping systems to relieve excess pressure control the level of pump withdrawal and prevent sudden increases in pressure depending on the configuration and the pilot controls.
  • The 55L valve is a spring-actuated direct-acting relief valve that can be installed in any position in a fire sprinkler piping system, in order to prevent a build-up of pressure that could damage the pipe.
  • Series 750 pressure relief valves are also used to relieve excess pressure, as well as to maintain a constant pressure in the pump discharge.
  • The 850 series tubular diaphragm fire relief valves offer a fast-acting deluge service and are equipped with integral cavitation protection.
  • Pressure relief valve cla val are not only durable and reliable, but also backed by more than 75 years of experience in control valves and customer service in our field.

Pressure relief valves

The valves pressure relief, also called safety valves or pressure relief valves (are different elements, please review ASME elements overpressure for containers), they are designed to relieve pressure when fluid exceeds a preset limit ( set pressure ). Its mission is to prevent the explosion of the protected system or the failure of an equipment or pipe due to excess pressure. There are also valves that relieve the pressure of a fluid when the temperature (and therefore the pressure) exceeds a limit set by the manufacturer

Normal uses

Safety valves can be found in industrial, commercial and domestic installations. In general, they are obligatory in facilities where they circulate or contain fluids subject, at some times, to inadmissible pressures.

Among the most common and visible examples of all are water heaters by accumulation . The safety or relief valves installed in the heaters or in the heater line are designed to open and release the pressure, letting the water out, in case the pressure exceeds a certain limit (ordinarily, about 8 ... 10 bar) to prevent bursting in case of thermostat failure , which could lead to water at a temperature above the boil and produce steam.

In the industry there are also examples such as air compressors or in pressure reduction systems for natural gas or LPG supply .

Other common uses of these valves are the relief of pressure in a blockage in the pump delivery system, or to relieve the increase in pressure due to a thermal expansion of a fluid confined in a closed system.

It is very important in these valves that the release of the fluid is done outwards, in a visible place, since the leak usually indicates a failure of the normal regulation system, and in this way the operator can know that there is a problem and that You must take steps to correct it. However, in industry, not all valves must release the fluid to the outside: in the case of hazardous gases or liquids, the release must be made to special containers.

Pressure relief valves are also used to control processes, in these cases the valves act by sending the fluids to certain places depending on system pressure.

Pressure Relief Valve Types

  1. Mechanics: The relief mechanism consists of a plug that keeps the exhaust closed. A calibrated spring keeps this plug in position preventing fluid from escaping from the container or pipe. When the internal pressure of the fluid exceeds the set pressure of the spring, the plug yields and the fluid exits the exhaust. Once the internal pressure decreases the cap returns to its original position. The pressure threshold that determines the fluid release point is adjusted by increasing or reducing the pressure that the spring exerts on the plug with a screw that passes through its center. Pressure and temperature relief valves have a second mechanism to release the pressure that is activated when a certain temperature is reached. These valves will open when one of these two events occurs: pressure above the threshold or temperature above the threshold, whichever occurs first (it actually only reacts to the pressure; the temperature increases the pressure).
  2. Electric: The electric relief valves have both modules, a pressure switch and an electrovalve . The pressure switch can be adjusted to trigger the solenoid valve at the desired pressure. Controlling shooting times.
  3. Electronics: More advanced systems instead of a pressure switch have a pressure transducer that sends a signal to a control room. Here an operator manually or by programming a computer decides at what pressure the solenoid valve opens or closes.