Browse Categories

Why You Need Relief Valves

The Importance of Relief Valves 

A relief valve or pressure relief valve (PRV) is a type of safety valve used to control or limit the pressure in a system. If there is no means of relief, the pressure can build up and cause process, instrument or equipment failure, or fire.  Relief valves can and should be used in many systems, but for now we are going to talk about boilers.

As the steam pressure within a boiler approaches the set pressure of the valve, the valve begins to react.  When pressure equilibrium is passed, a disc inside the valve starts to lift off its seat. The moment this happens, steam is suddenly released all around the disc to what is called the “huddling chamber.” This chamber increases the area of the disc that sees steam pressure, thus increasing force. This increased area under steam pressure makes the pressure much more unbalanced and opens the valve to relieve the pressure. Closure of the valve occurs only after the boiler pressure is dropped several pounds below the set point.

Proper installation of a steam relief valve is somewhat simple as long as two areas of concern are followed:

The first area of concern is valve distortion. Valve distortion occurs when the valve is improperly wrenched in, using the valve body instead of supplied wrench flats. Distortion also occurs when the discharge side of the safety relief valve is made to bear the weight of the discharge piping. To prevent this distortion use a short nipple from the valve to an independently supported bell reducer or drip pan elbow. These valves are precision devices and any distortion will affect accuracy and calibration.

The second area of concern is discharge piping. For a safety valve to do its job it must be sized properly to adequately relieve all the steam the boiler is capable of producing while operating at its maximum. All piping to or from a safety relief valve must be at least as large as the valve’s connections. Also, the restrictive effect of elbows and the friction losses in pipe must be taken into account. For this reason, piping runs should be as short as possible and pipe sizes should be generous.


Shop our Relief Valves

Tags

bas networking distech building automation iot ot jace control valves hvac systems industrial valves eclypse tosibox jci bas network 8000 9000 dwyeromega remote display hvac pumps hydronic systems commercial hvac centrifugal pumps chilled water systems heating water systems boiler safety boiler components industrial heating equipment heating systems chiller Pneumatic Electro-Mechanical and DDC systems maintenance calibration remote bacnet n4 automation honeywell control panels network configuration port security network control smart buildings energy management ethernet based bas network guidelines managed switches optimizer commander johnson controls sma device count points Gas Meters Diaphragm Rotary meters gas trains fuel train gas supply commercial boiler burner ief transmitters Gas Valves for boilers Vent Valves Pilot Gas Valves switches for boilers a temperature sensor honeywell i4006 honeywell l6006c honeywell l91b temperature limit switches gas pressure limit switches pump selection pump sizing hydronic pump design pump fundamentals gpm flow rate total dynamic head tdh head pressure closed loop systems open loop systems glycol systems pump control strategies vfd pumps ecm pumps bas integration pump configuration inline pumps end suction pumps split case pumps redundant pumping lead lag pumps npsh hvac fundamentals industry terms pumps in hvac hydronic pump basics boiler systems hvac pump operation gpm and head pressure ahr boiler control Low Water Cut off Air Handler Unit AHU Air Handling Units HVAC Equipment york compressor tp valve temperature and pressure relief valve water heater safety domestic hot water systems plumbing safety devices pressure relief valves thermal expansion protection potable water systems water heater components mechanical code compliance plumbing code requirements boiler vs tp valve hot water storage tanks safety valves facility maintenance boiler relief valves ief electromagnetic flow transmitter optional lcd AI future pressure class belimo gas monitor air quality training certification atrius cloud platform fireye burnlogix yb honeywell q tosi n5 bacnetsc sc niagara fx heating season checklist tc500 promo chart recorder industrial cxc customer center dcv sensor network security cyber ul508a industrial solutions engineering solutions panel assembly custom control panels commercial panels gas regulator sizing gas safety inlet pressure outlet pressure flow rate natural gas propane regulators subnet it managed ip switch vlan setup quality of service qos spanning tree protocol stp routing configuration network management lldp setup energy efficiency ethernet managed network switch benefits ot network energy savings building solutions connected power building management bms transformers din rail transformer functional devices transformer in a box ai in real estate cybersecurity data integration realcomm ibcon sustainability sensors controllers interfaces
Show All

Posts

2026 2025
December November October September August July June May April February January
2024
November October September August July June May April March February January
2023
December November October September August July June May April March
2022