Gas valves are used to handle and control the flow of gaseous media such as liquefied petroleum and natural gas. They are made of metal or plastic and vary in terms of valve size, pressure rating, number of ports, and flow. Connection types consist of bolt flanges, clamp flanges, union connections, tube fittings, butt welds, socket welds, and internal or external threads.
Gas Valve Types
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.
Honeywell Universal Gas Valves
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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 valvs 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
BS 1552 - Specification for open bottomed taper plug valves
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Related Products & Services
Air Pressure Regulators
Air pressure regulators control pressure in air lines (usually adjustable) to remove fluctuations and maintain consistent pressure for pneumatic devices.
Air valves allow metered fluid flow in one or both directions. They are used in pneumatic circuits to regulate the rate of activation or exhaust of cylinders and other pneumatic devices.
Control valves or proportional valves are power-operated devices used to modify fluid flow or pressure rate in a process system.
Diaphragm valves close by means of a flexible diaphragm attached to a compressor.
Plastic valves are made from plastic materials and are used in applications that require corrosion resistance and/or chemical handling.
Quarter-turn plug valves use a cylindrical or tapered plug with a hole in the center to control straight through flow when in the open position.
Sanitary valves are designed for applications requiring clean or sterile processing.