Types
The inside of an extremely large butterfly valve
Valves are quite diverse and may be classified into a number of basic types. Valves may also be classified by how they are actuated:
Hydraulic
Pneumatic
Manual
Solenoid
Motor
Basic types
Valves can be categorized into the following basic types:
Duplex ball valve
Ball valve, for on/off control without pressure drop, and ideal for quick shut-off since a 90º turn offers complete shut-off angle, compared to multiple turns required on most manual valves.
Butterfly valve, for flow regulation in large pipe diameters.
Ceramic Disc valve, used mainly in high duty cycle applications or on abrasive fluids. Ceramic disc can also provide Class IV seat leakage
Check valve or non-return valve, allows the fluid to pass in one direction only.
Three check valves in corrosion-resistant Hastelloy
Choke valve, a valve that raises or lowers a solid cylinder which is placed around or inside another cylinder which has holes or slots. Used for high pressure drops found in oil and gas wellheads.
Diaphragm valve, which controls flow by a movement of a diaphragm. Upstream pressure, downstream pressure, or an external source (e.g., pneumatic, hydraulic, etc.) can be used to change the position of the diaphragm.
Gate valve, mainly for on/off control, with low pressure drop.
Stainless steel gate valve
Globe valve, good for regulating flow.
Knife valve, similar to a gate valve, but usually more compact. Often used for slurries or powders on/off control.
Needle valve for accurate flow control.
Pinch valve, for slurry flow regulation.
Piston valve, for regulating fluids that carry solids in suspension.
Plug valve, slim valve for on/off control but with some pressure drop.
Poppet valve
Spool valve, for hydraulic control
Thermal expansion valve, used in refrigeration and air conditioning systems.
Pressure Relief Valves
Sampling valves
Safety valve
Specific types
Aspin valve: a cone-shaped metal part fitted to the cylinder head of an engine
Ball cock: often used as a water level controller (cistern)
Bibcock: provides a connection to a flexible hosepipe
Blast valve: prevents rapid overpressures in a fallout shelter or a bunker
Cock: colloquial term for a small valve or a stopcock
Demand valve: on a diving regulator
Double beat valve
Double check valve
Duckbill valve
Flipper valve
Flow control valve: an application which maintains a variable flow rate through the valve
Heimlich valve: a specific one-way valve used on the end of chest drain tubes to treat a pneumothorax
Foot valve: a check valve on the foot of a suction line to prevent backflow
Four-way valve: was used to control the flow of steam to the cylinder of early double-acting steam engines
Freeze seal/Freeze plug: in which freezing and melting the fluid creates and removes a plug of frozen material acting as the valve
Gas pressure regulator regulates the flow and pressure of a gas
Heart valve: regulates blood flow through the heart in many organisms
Leaf valve: one-way valve consisting of a diagonal obstruction with an opening covered by a hinged flap
Pilot valve: regulate flow or pressure to other valves
Plunger Valve: To regulate flow while lowering the pressure
Poppet valve and sleeve valve: commonly used in piston engines to regulate the fuel mixture intake and exhaust
Pressure regulator or pressure reducing valve (PRV): reduces pressure to a preset level downstream of the valve
Pressure sustaining valve, or back-pressure regulator: maintains pressure at a preset level upstream of the valve
Presta and Schrader valves are used to hold the air in bicycle tires
Reed valve: consists of two or more flexible materials pressed together along much of their length, but with the influx area open to allow one-way flow, much like a heart valve
Regulator: used in SCUBA diving equipment and in gas cooking equipment to reduce the high pressure gas supply to a lower working pressure
Rocker valve
Rotary valves and piston valves: parts of brass instruments used to change their pitch
Rupture disc: a one time use replaceable valve for rapid pressure relief, used to protect piping systems from excessive pressure or vacuum; more reliable than a safety valve
Saddle valve: where allowed, is used to tap a pipe for a low-flow need
Safety valve or relief valve: operates automatically at a set differential pressure to correct a potentially dangerous situation, typically over-pressure
Schrader valve: used to hold the air inside automobile tires
Solenoid valve: an electrically controlled hydraulic or pneumatic valve
Stopcock: restricts or isolates flow through a pipe
Swirl valve: A specially designed Joule-Thompson pressure reduction/expansion valve imparting a centrifugal force upon the discharge stream for improving gas-liquid phase separation
Tap (British English), faucet (American English): the common name for a valve used in homes to regulate water flow
Thermal expansion valve, used in air conditioning and refrigeration systems.
Thermostatic Mixing Valve
Thermostatic Radiator Valve
Trap primer: sometimes include other types of valves, or are valves themselves
Vacuum breaker valve: prevents the back-siphonage of contaminated water into pressurized drinkable water supplies
