Gas Valves Information
Gas valves are flow control devices used to handle and control the flow of gases such as liquefied petroleum, oxygen, and sour and natural gas. They are available in a variety of metal or plastic materials that are compatible with the media controlled and pressure requirements. Gas valves are available in most of the basic valve technologies such as ball, butterfly, plug, needle, and various check valve designs. They are used in many industrial, commercial and residential applications for on/off, modulating, and control applications.
Types of Gas Valves
There are many types of gas valves, including:
- Angle valves admit gases at an angle and allow for maximum flow.
- Balancing valves maintain a consistent temperature and compensate for pressure drops.
- Ball valves provide tight shut-offs, but are not suitable for sanitary applications.
- Butterfly valves permit flow in only one direction.
- Block-and-bleed, blow-off, cartridge, check, and control valves are commonly available.
- Diaphragm valves separate the flow of gases from the closure element.
- Directional valves steer flow through selected passages.
- Diverter valves also redirect gas flow.
- Drain valves reduce surplus media.
- Gate or knife valves are linear motion valves in which a closure element slides into the flow to shut off the stream.
- Globe and pinch valves are other types of linear motion devices.
- Metering and mixing valves are used in specialized applications.
- Needle valves have a slender, tapered point at the end of a valve stem.
- Plug or stop-cock valves are designed for both on/off and throttling functions.
- Other types include poppet valves, pressure relief valves, regulators, safety valves, and sampling valves. Compressor valves as well as servo, shut off, solenoid, spool, toggle, underwater, and vacuum relief or anti-siphon gas valves are also available.
Applications & Industries
Gas valves are used in a variety of applications and industries. For example:
High-purity gas valves are used to handle gases such as nitrogen, argon, oxygen, and hydrogen.
Materials of Construction
Gas valves are made from metallic elements such as:
- Aluminum offers good electrical and thermal conductivity, high reflectivity, and resistance to oxidation.
- Copper is ductile and malleable and one of the best conductors of heat and electricity. Both brass and bronze are copper alloys.
- Brass provides good bearing properties and low magnetic permeability.
- Sintered bronze can be impregnated with materials such as oil and graphite.
- Steel is a commercial iron that differs from cast iron both in terms of its malleability and lower carbon content.
- Ductile iron provides the machinability and corrosion resistance of cast iron while providing additional strength and toughness.
- Stainless steel is chemical and corrosion resistant and can have relatively high pressure ratings.
Gas valves can also be constructed of a variety of plastics, including:
- Acetal polymers are semi-crystalline and offer excellent inherent lubricity, fatigue resistance, and chemical resistance.
- Polyvinyl chloride (PVC) is a widely used material with good flexibility, smooth surface, and nontoxic properties.
- Chlorinated polyvinyl chloride (CPC), a higher grade plastic used in water distribution systems, is suitable for high temperatures.
- Polytetrafluoroethylene (PTFE) is an insoluble compound that exhibits a high degree of chemical resistance and a low coefficient of friction.
- Polypropylene (PP) is similar to PTFE, but can be used in exposed applications because of its resistance to ultraviolet (UV) light, weathering, and ozone.
- Polyvinylidene fluoride (PVDF) is a fluoropolymer with better strength and lower creep than similar materials.
ASME B16.33 - Manually operated metallic gas valves for use in gas piping systems
ANSI/IAS NGV 4.6 - Manually operated valves for natural gas dispensing systems
A-A-59860 - Valves, cylinder, gas