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Encyclopedia > Safety valve
Oxygen Safety Valve
Oxygen Safety Valve
ND250-Safety Valves
ND250-Safety Valves

A safety valve is a valve mechanism for the automatic release of a gas from a boiler, pressure vessel, or other system when the pressure or temperature exceeds preset limits. It is part of a bigger set named Pressure Safety Valves (PSV) or Pressure Relief Valves (PRV). The other parts of the set are named relief valves, safety relief valves, pilot-operated safety relief valves, low pressure safety valves, vacuum pressure safety valves. Image File history File links Question_book-3. ... Image File history File links Oxygen-Safetyvalve. ... Image File history File links Oxygen-Safetyvalve. ... // These water valves are operated by handles. ... A boiler is a closed vessel in which water or other fluid is heated. ... Steel Pressure Vessel A pressure vessel is a closed, rigid container designed to hold gases or liquids at a pressure different from the ambient pressure. ... For other uses, see System (disambiguation). ... Relief Valve A relief valve opens to release excess pressure when the pressure is too high to protect the vessel or other equipment from overpressurization. ... The relief valve is a type of valve used to control or limit the pressure in a system or vessel which can build up by a process upset, instrument or equipment failure, or fire. ...


Safety valves were first used on steam boilers during the industrial revolution. Early boilers without them were prone to accidental explosion when the operator allowed the pressure to become too high, either deliberately or through incompetence.

Contents

Function and design

Proportional-Safety Valve
Proportional-Safety Valve

The earliest and simplest safety valve used a weight to hold the pressure of the steam, (this design is still commonly used on pressure cookers); however, these were easily tampered with or accidentally released. On the Stockton and Darlington Railway, the safety valve tended to go off when the engine hit a bump in the track. A valve less sensitive to sudden accelerations used a spring to contain the steam pressure, but these (based on Salter spring balances) could still be screwed down to increase the pressure beyond design limits. This dangerous practice was sometimes used to marginally increase performance of a steam engine. In 1856 John Ramsbottom invented a tamper-proof spring safety valve which became universal on railways. Image File history File links Download high-resolution version (320x798, 47 KB) Original: http://de. ... Image File history File links Download high-resolution version (320x798, 47 KB) Original: http://de. ... Pressure cooking is a method of cooking things at high heat without boiling them. ... Opening of the Stockton and Darlington Railway by John Dobbin, circa 1825. ... John Ramsbottom may refer to: John Ramsbottom (1814–1897), an English mechanical engineer who created many inventions for railways, John Ramsbottom (1885–1974), a British mycologist. ...


Safety valves also evolved to protect equipment such as pressure vessels (fired or not) and heat exchangers. Safety valve term should be limited to compressible fluid application (gas, vapor, steam). Steel Pressure Vessel A pressure vessel is a closed, rigid container designed to hold gases or liquids at a pressure different from the ambient pressure. ... A heat exchanger is a device built for efficient heat transfer from one fluid to another, whether the fluids are separated by a solid wall so that they never mix, or the fluids are directly contacted. ...


The two general types of protection encountered in industry are thermal protection and flow protection.


For liquid-packed vessels, thermal relief valves are generally characterized by the relatively small size of the safety valve necessary to provide protection from excess pressure caused by thermal expansion. In this case a small valve is adequate because most liquids are nearly incompressible, and so a relatively small amount of fluid discharged through the relief valve will produce a substantial reduction in pressure.


Flow protection is characterized by safety valves that are considerably larger than those mounted in thermal protection. They are generally sized for use in situations where significant quantities of gas or high volumes of liquid must be quickly discharged in order to protect the integrity of the vessel or pipeline.


Legal and code requirements in industry

In the petroleum refining, petrochemical and chemical manufacturing, natural gas processing and power generation industries, the term safety valve is associated with the terms pressure relief valve (PRV), pressure safety valve (PSV) and relief valve. Image File history File links Wikitext. ... View of Shell Oil Refinery in Martinez, California. ... Petrochemicals are chemical products made from raw materials of petroleum (hydrocarbon) origin. ... A Chemical plant is an industrial process plant that manufactures chemicals, usually on a large scale. ... A natural gas processing plant Natural gas processing plants are used to purify the raw natural gas extracted from underground gas fields and brought up to the surface by gas wells. ... For other uses, see Power station (disambiguation). ...


The generic term is or Pressure Relief Valve (PRV) or Pressure Safety Valve (PSV) Relief Valve A relief valve opens to release excess pressure when the pressure is too high to protect the vessel or other equipment from overpressurization. ...


Relief Valve (RV): automatic system that relief by static pressure on a liquid. It specifically open proportionally with pressure increasing.


Safety Valve (SV): automatic system that relief by static pressure on a gas. It specifically open almost straight to full lift after a pop sound.


Safety Relief Valve (SRV): automatic system that relief by static pressure on both gas and liquid.


Pilot-Operated Safety Relief Valve (POSRV): automatic system that relief by remote command from a pilot on which the static pressure (from equipment to protect) is connected.


Low Pressure Safety Valve (LPSV): automatic system that relief by static pressure on a gas. The pressure is small and near the atmospheric pressure. Atmospheric pressure is the pressure at any given point in the Earths atmosphere. ...


Vacuum Pressure Safety Valve (VPSV): automatic system that relief by static pressure on a gas. The pressure is small, negative and near the atmospheric pressure.


Low and Vacuum Pressure Safety Valve (LVPSV): automatic system that relief by static pressure on a gas. The pressure is small, negative or positive and near the atmospheric pressure.


RV, SV and SRV are spring operated (even said spring loaded). LPSV and VPSV are spring operated or weight loaded.


In most countries, industries are legally required to protect pressure vessels and other equipment by using relief valves. Also in most countries, equipment design codes such as those provided by the ASME, API and other organizations like ISO (ISO 4126) must be complied with and those codes include design standards for relief valves.[1][2] ASME redirects here. ... The American Petroleum Institute, commonly referred to as API, is the main U.S. trade association for the oil and natural gas industry, representing about 400 corporate members involved in all aspects of the industry. ...


The main standards, laws or directives are:

  • ASME (American Society of Mechanical Engineers) Boiler & Pressure Vessel Code, Section VIII, Division 1
  • API (American Petroleum Institute) Recommended Practice 520 and API Standard 526, API Standard 2000 (low pressure -Storage tank)
  • ISO 4126 (originated from from European Union directives)
  • EN 764-7 (from CEN - European Committee for Standardization - originate from European Union directives)
  • AD Merckblatt (German)
  • PED 97/23/EC (Pressure Equipment Directive - European Union)

The American Society of Mechanical Engineers (ASME) is a professional body, specifically an engineering society, focused on mechanical engineering. ... ASME redirects here. ... API may refer to: In computing, application programming interface In petroleum industry, American Petroleum Institute In education, Academic Performance Index This page concerning a three-letter acronym or abbreviation is a disambiguation page — a navigational aid which lists other pages that might otherwise share the same title. ... The American Petroleum Institute, commonly referred to as API, is the main U.S. trade association for the oil and natural gas industry, representing about 400 corporate members involved in all aspects of the industry. ...

Water heaters

Temperature and Pressure safety valve on a water heater.

They are required on water heaters, where they prevent disaster in certain configurations in the event a thermostat should fail. There are still occasional, spectacular failures of older water heaters that lack this equipment. Houses can be levelled by the force of the blast.[3] Image File history File linksMetadata Download high-resolution version (2580x1932, 891 KB) Picture of a temperature and pressure safety valve on a water heater. ... Image File history File linksMetadata Download high-resolution version (2580x1932, 891 KB) Picture of a temperature and pressure safety valve on a water heater. ... A trio of propane hot water heaters. ... Bi-metallic thermostat for buildings A thermostat is a device for regulating the temperature of a system so that the systems temperature is maintained near a desired setpoint temperature. ...


Pressure cookers

Pressure cookers are pots for cooking with a pressure proof lid. Cooking at pressure allows the temperature to rise above the boiling point of water (100 degrees Celsius at sea level ) which speeds up the cooking and makes the cooking more thorough. Pressure cooking is a method of cooking things at high heat without boiling them. ... For considerations of sea level change, in particular rise associated with possible global warming, see sea level rise. ...


Pressure cookers usually have two safety valves. One in a hole upon which a weight sits. The other is a sealed rubber grommet which is ejected in a controlled explosion if the first valve gets blocked. Some rubber grommets. ...


The term safety valve is also used metaphorically. This article is about metaphor in literature and rhetoric. ...


See also

Boiler explosions are catastrophic failures of boilers. ... The relief valve is a type of valve used to control or limit the pressure in a system or vessel which can build up by a process upset, instrument or equipment failure, or fire. ... A Pilot-Operated Relief Valve is used to relieve large flows with small pressure differential. ...

External links

Safety Valves Why are safety valves required? What different types are available and how are they selected, sized and installed? - Spirax Sarco



The main manufacturers of pressure safety valves are:

  • Motherwell Tank Protection (UK) ... LPSV POSRV
  • Sarasin-RSBD (France) ... SV SRV POSRV LPSV VPSV LVPSV
  • Sapag (France) ... SV SRV
  • Crosby (USA) ... SV SRV POSRV
  • Consolidated (USA) ... SV SRV POSRV
  • Anderson-Greenwood (USA) ... POSRV
  • Farris (Canada) ... SV SRV POSRV
  • Fukui (Japan) ... SV SRV POSRV
  • ARI-Armaturen (Germany)
  • Leser (Germany, USA, France) ... SRV
  • Bopp & Reuter (Germany) ... SV SRV
  • Besa (Italy) ... SRV
  • Tecval S.A (Colombia)

References

  1. ^ List of countries accepting the ASME Boiler & Pressure Vessel Code
  2. ^ API 5210-1, Sizing and Selection of Pressure-Relieving Devices
  3. ^ Elaine Porterfield, Paul Shukovsky, and Lewis Kamb (Saturday, July 28, 2001). Four hurt as water heater explodes. seatlepi.nwsource.com, Retrieved on Saturday, May 12, 2007

  Results from FactBites:
 
Safety Valve Installation : Spirax Sarco Learning Centre (3136 words)
The seat tightness is affected by three main factors; firstly by the characteristics of the safety valve, secondly by the installation of the safety valve and thirdly, by the operation of the safety valve.
The outlet of the safety valve is connected to a 6 mm internal diameter pipe, the end of which is held 12.7 mm below the surface of water contained in a suitable, transparent vessel.
Safety valves that are installed outside of a building for discharge directly into the atmosphere should be covered using a hood.
Safety valve - Wikipedia, the free encyclopedia (495 words)
A safety valve is a valve mechanism for the automatic release of a gas from a boiler, pressure vessel, or other system when the pressure or temperature exceeds preset limits.
Safety valves were first used on steam boilers during the industrial revolution.
Thermal relief valves are generally characterized by the relatively small size of the safety valve necessary to provide protection from thermal expansion pressure increases in liquid-packed vessels.
  More results at FactBites »

 
 

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