Pressure relief valves are designed to provide protection from over-pressure in steam, gas, air, and liquid lines. Relief valves and back pressure regulators are the same device, only differing in application. The pressure relief valve "lets off steam" when safe pressures are exceeded, then closes again when pressure drops to a preset level. A back pressure regulator maintains upstream pressure at the desired setting by opening to allow excess upstream pressure to flow downstream.
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Q & A on Pressure Relief Valves
We asked our users for their input on Pressure Relief Valves. Here are the results of 62 users familiar with Pressure Relief Valves.
Who Took Our Poll? | Design Trends | Applications and Use | Features | Buying AdviceDesign TrendsTop
What new technologies are influencing pressure relief valve design?
7 answers
The pressure relief and safety valves that I inspect on a daily schedule have not really changed in design over the years other than the huddling chamber safety valves on high pressure boilers.
~Joseph T, Senior Boiler and Machinery Inspector, Florence, MS
To be able to in situ test a safety valve on line and live the valve has to be designed to be able to carry out this test; most good valve companies are now recognizing this.
~Tony O D, Owner/Director of Valve Repair Company, Cork, IE
New specs in boilers, will influence the pressure relief valve design
~Marketing/Sales, Tracyville, Canada
More and more sanitary pressure relief valve applications.
~Bob C, Sr. Mgr Manuf Engr, Florence, US of A
Oil and gas exploration
~Jose P, Pressure relief valve maintenance and calibration, DOHA, QATAR
Information technology
~Ramon P., Design Engineer, B.s.b., Brunei darussalam
Pilot connection
~Engineering, Design, Yanbu, Saudi Arabia
From your perspective, which companies are creating the most innovative pressure relief valves?
6 answers
I would say, Dresser - Consolidated Safety/Safety Relief Valves
~Marketing/Sales, Tracyville, Canada
Conbraco, Kunkle and Consolidated Valve
~Joseph T, Senior Boiler and Machinery Inspector, Florence, MS
Leser, Crosby and Farris
~Tony O D, Owner/Director of Valve Repair Company, Cork, IE
Dresser and Crosby
~Jose P, Pressure relief valve maintenance and calibration, DOHA, QATAR
Global spec
~Ramon P., Design Engineer, B.s.b., Brunei darussalam
Kunkel
~Jon F, Engineer, Grand Island, NE
Applications and UseTop
What are some of the applications you have used pressure relief valves for?
15 answers
We use them on our steam boilers in accordance with the boiler codes. We also use them in combination with temperature relief valves on our hot water tanks and on expansion tanks.
~Technical Support/Services, TROY, NY
Boilers DA Tanks Water heaters Water Pumps running off a Pressure Transducer Hydraulic Pumps Ammonia Refrigeration.
~Jon F, Engineer, Grand Island, NE
Air tanks, air / oil separators, boilers, water heaters and unfired pressure vessels in process plants.
~Joseph T, Senior Boiler and Machinery Inspector, Florence, MS
Steam, Oil, Dowtherm, Siltherm ,Water, Air, Nitrogen , Oxygen
~Tony O D, Owner/Director of Valve Repair Company, Cork, IE
Relieving Capacity of the Crude Distillation Column at ARAMCO
~Engineering, Design, Yanbu, Saudi Arabia
Oil refining, Pulp/Paper Mills, Power Plants, Hospitals.
~Marketing/Sales, Tracyville, Canada
Pressure tanks, water pressure main line, hot water
~Ramon P., Design Engineer, B.s.b., Brunei darussalam
Boilers, Hot water Heater, Sewer lift station.
~Quality Control/Assurance, San antonio, TX
Have used the valves in air compressors
~Marketing/Sales, SUBANG JAYA, Malaysia
Tanks and piping pressure relief.
~Bob C, Sr. Mgr Manuf Engr, Florence, US of A
Cilinder positioning/ locating
~Engineering, Process/Production, Fleetwood, Great Britain
Boilers and pressure vessels
~Jose P, Pressure relief valve maintenance and calibration, DOHA, QATAR
Boilers & Pressure Vessels
~Glenn M., Inspector, Greater Sudbury, Canada
Hydraulic,pneumatic
~Engineering, Process/Production, Barabil, India
Hot water systems
~Architect/Builder/Contractor, San Juan, PR
Please share with us any “non-standard” applications that pressure relief valves have been used for.
4 answers
Pressure relief valves used on boilers and pressure vessels with no lifting lever for manual testing of the valve, other than relief valves on dowtherm units which by code have no lifting lever and are installed to discharge to the suction side of the dowtherm pump if they lift on pressure.
~Joseph T, Senior Boiler and Machinery Inspector, Florence, MS
Pressure cooker, storage container, food storage container
~Ramon P., Design Engineer, B.s.b., Brunei darussalam
As an inappropriate pressure control
~Glenn M., Inspector, Greater Sudbury, Canada
Spence and watts
~Technical Support/Services, TROY, NY
Do you know of any disastrous mistakes that occurred due to the incorrect usage of pressure relief valves?
6 answers
Not recently but nation wide approximately 2% of boilers and pressure vessels have exploded due to incorrect relief valves.
~Joseph T, Senior Boiler and Machinery Inspector, Florence, MS
Nothing disastrous but lots of incorrect installations, either installation errors and or wrong valve for the application.
~Glenn M., Inspector, Greater Sudbury, Canada
While selecting PRV , didn't consider the temperature factor and valve failed in furnace.
~Jose P, Pressure relief valve maintenance and calibration, DOHA, QATAR
Either under size or oversize
~Ramon P., Design Engineer, B.s.b., Brunei darussalam
Ammonia leaks due to failure
~Jon F, Engineer, Grand Island, NE
3-way ordered instead 2-way
~Engineering, Design, Yanbu, Saudi Arabia
FeaturesTop
What would your design or feature "wish list" be for this product?
8 answers
A built in micro chip that one can upload or download service history, a bit like your key if you own a BMW the service agent can download all previous history from this.
~Tony O D, Owner/Director of Valve Repair Company, Cork, IE
A relief valve that controls a louvered opening to open up so that the heat (hot air) of the enclosed car could be release automatically during parking.
~Ramon P., Design Engineer, B.s.b., Brunei darussalam
One that would make a longer than 5- Year to re cert. or replace.
~Jon F, Engineer, Grand Island, NE
Lower cost, compressed air actuation to clean in place.
~Bob C, Sr. Mgr Manuf Engr, Florence, US of A
Valve performance and easy to maintenance
~Jose P, Pressure relief valve maintenance and calibration, DOHA, QATAR
Easily tested, serviced, installed
~Glenn M., Inspector, Greater Sudbury, Canada
None at the present time.
~Joseph T, Senior Boiler and Machinery Inspector, Florence, MS
Dressers Consolidated
~Engineering, Design, Yanbu, Saudi Arabia
Is there any advice you want to share with users to help them avoid common errors in selection or usage of pressure relief valves?
8 answers
Read the name plate to determine the MAWP ( Maximum Allowable Working Pressure) and Minimum relief capacity. Example : Hot Water Heating Boiler - MAWP - 30 p.s.i. with a relief capacity of 1,500,000 Btu. The relief valve should be set no higher than 30 p.s.i. and have a relief capacity of no less than 1,500,000 BTU and be stamped A.S.M.E.
~Joseph T, Senior Boiler and Machinery Inspector, Florence, MS
Avoid cheap and cheerful if possible they will cost you more in the long run. Also avoid oversizing a safety valve, this can be as dangerous as undersizing.
~Tony O D, Owner/Director of Valve Repair Company, Cork, IE
Be precise with vendor to know what is supplied; I mean 2 way or 3 way valve.
~Engineering, Design, Yanbu, Saudi Arabia
Be very sure you know your application what you want to do.
~Jon F, Engineer, Grand Island, NE
Check relief flow capacity not just pressure setting.
~Bob C, Sr. Mgr Manuf Engr, Florence, US of A
Provide all service conditions and requirements.
~Jose P, Pressure relief valve maintenance and calibration, DOHA, QATAR
Be sure of code requirements for application.
~Glenn M., Inspector, Greater Sudbury, Canada
Refer to design specs
~Ramon P., Design Engineer, B.s.b., Brunei darussalam
Buying AdviceTop
Do you have any advice for people relative to buying or using pressure relief valves?
8 answers
Purchase the type of relief valve for the application of the vessel that the valve is installed. Example : air tank ( relief valve intended for air service) or hot water heating boiler (relief valve intended for hot water service) etc.
~Joseph T, Senior Boiler and Machinery Inspector, Florence, MS
Sizing a pressure relief valve to make sure of flow rates is vital before purchase, also Material spec is very important i.e carbon steel , stainless steel etc.
~Tony O D, Owner/Director of Valve Repair Company, Cork, IE
Buyers must not do search for what they may feel are equivalent to specified valve.
~Glenn M., Inspector, Greater Sudbury, Canada
Ensure spare parts availability and after sales services.
~Jose P, Pressure relief valve maintenance and calibration, DOHA, QATAR
Check relief flow capacity not just pressure setting.
~Bob C, Sr. Mgr Manuf Engr, Florence, US of A
Don't buy cheap, you get what you pay for.
~Jon F, Engineer, Grand Island, NE
Always use global spec
~Ramon P., Design Engineer, B.s.b., Brunei darussalam
Witness test
~Engineering, Design, Yanbu, Saudi Arabia