Welcome to MPI’s third glossary of industry terminology, this time featuring brief descriptions of a wide range of different valve types. Plus, we also included a list of important industry standards at the end.
VALVE TYPES
3-Way Valve – A valve with three ports used to mix, divert, or switch flow between different lines. Common in HVAC systems and process piping.
4-Way Valve – A valve with four ports typically used in reversing applications, such as controlling the direction of flow in heat pump systems.
Air Release Valve – A valve that automatically releases trapped air from a pressurized pipeline while it is operating under pressure. Essential for maintaining flow efficiency and preventing air-related disruptions.
Angle Body Valve – A compact valve efficient in thermal and space-constrained systems.
Angle Seat Valve – Pneumatically operated valve often used in steam, water, or compressed air service.
Angle Valve – A valve with an inlet and outlet forming a 90-degree angle, often used for throttling or flow direction changes.
Back Flow Preventer – A device that prevents reverse flow of water or other substances into the potable water supply.
Balancing Valve – A valve used to regulate and balance fluid flow in a hydronic heating or cooling system, ensuring even distribution and efficient operation.
Ball Check Valve – Uses a ball as the check mechanism to prevent backflow.
Ball Valve – A valve with a spherical closure element that rotates to open or close the flow path.
Butterfly Valve – A valve with a rotating disc that controls flow, commonly used for on/off or modulating services.
Check Valve – A valve that allows flow in one direction and prevents backflow.
Choke Valve – Used in oil & gas to control pressure and flow from wells.
Combination Air/Vacuum Valve – A multifunction valve that allows large volumes of air to escape during filling and to enter during draining, while also releasing smaller pockets of air during operation. Combines the functions of air release and vacuum valves.
Cone Valve – A full-bore, high-performance control valve with a cone-shaped plug that moves axially to modulate flow. Known for its ability to handle high pressures and flow rates with minimal cavitation and vibration, often used in dams, reservoirs, and pump stations.
Control Valve – A valve that modulates flow, pressure, or temperature, by varying the size of the flow passage, in response to a signal from a controller.
Cryogenic Valve – A valve designed with an extended bonnet for extremely low temperatures, typically for liquefied gases.
Diaphragm Valve – Uses a flexible diaphragm that presses against a seat to control flow.
Double Door Check Valve – A type of check valve with two spring-loaded half-circle doors (or plates) that open with forward flow and close to prevent reverse flow. Often used for low-pressure drop applications in water and HVAC systems.
Eccentric Plug Valve – A valve with an offset plug that rotates to seal against the body, ideal for throttling.
Expanding Gate Valve – A gate valve with a mechanism that expands the gate to seal against the seats.
Extended Blow Down Valve – A valve with extended piping used to discharge sediment or pressure from vessels.
Fire Gate Valve – A fire-rated or fireproof gate valve.
Fire Hydrant – A specific type of hydrant installed on a water distribution system, providing firefighters with access to high-pressure water during emergencies. Fire hydrants come in dry-barrel (cold climates) and wet-barrel (warm climates) types.
Gate Valve – A valve that uses a gate to stop or start flow.
Globe Valve – A valve with a disc that moves perpendicular to the seat, ideal for throttling.
Hydrant – A general term for a discharge outlet that allows access to a water supply, typically for flushing or fire suppression. Includes various types such as yard hydrants and wall hydrants.
Hydraulic Control Valve – A valve that uses hydraulic fluid pressure to control the flow, pressure, or direction of water or other fluids in a piping system. It typically includes pilot valves and actuators to automatically regulate valve operation in response to system conditions.
Knife Gate Valve – A gate valve with a sharp-edged blade to cut through thick fluids or slurries.
Lift Check Valve – A check valve where the disc lifts off the seat to allow flow.
Mixing Valve – A valve that blends two fluid streams (typically hot and cold water) into a single output. Used in plumbing and processing systems for safety and comfort.
Mud Valve – A valve typically installed at the bottom of tanks or basins for draining sludge or sediment. Commonly a rising-stem gate valve operated from above.
Needle Valve – A valve with a fine, tapered point for precise flow control.
Pinch Valve – Uses a pinching mechanism to obstruct flow in flexible tubing, often used in slurry or chemical service.
Post Indicator Valve (PIV) – Indicates valve open/closed status in fire protection systems.
Pressure Regulating Valve (Pressure Reducing Valve) – A valve that controls the outlet pressure by dynamically limiting the valve opening in response to fluctuations in the downstream pressure.
Pressure Relief Valve – Designed to release pressure when it exceeds a set limit, for safety.
Pump Check Valve – A check valve or control valve installed on the discharge side of a pump to prevent backflow when the pump is off. Designed to synchronize its operation with pump start/stop cycles and minimize water hammer.
Pump Control Valve – A valve designed to manage pressure and flow during pump operation.
Reduced Port Valve – A valve with a smaller bore than the pipe diameter, restricting flow.
Riser Valve – A valve installed on a vertical pipe ("riser") used to control flow in fire protection, irrigation, or plumbing systems. Often refers to valves located in riser rooms in buildings.
Rotary Control Valve (RCV) – A type of control valve where the closure element (such as a plug or disc) rotates to modulate flow. Used for smooth operation and precise control.
Rubber Flapper Check Valve – A check valve with a resilient disc that swings on an integral resilient hinge to block reverse flow.
Silent Check Valve – A check valve designed with a spring-assisted disc that closes quietly before reverse flow occurs, minimizing water hammer and noise. Frequently used in vertical and high-rise piping systems.
Slide Gate – A flat, vertical gate that slides in a frame to start or stop flow in open channels or large pipelines. Common in wastewater treatment plants, flood control structures, and in the handling of bulk dry materials.
Slurry Valve – Engineered to handle abrasive or high-solid content fluids.
Solenoid Valve – Electromagnetically controlled valve for fluid or gas flow.
Surge Relief Valve – A valve designed to relieve pressure spikes in a system.
Swing Check Valve – A check valve with a disc that swings on a hinge to block reverse flow.
Telescoping Valve – A valve with an adjustable vertical pipe (telescoping stem) used in basins or tanks to draw water at varying levels. Commonly used in wastewater or stormwater structures for flow control.
Vacuum Release Valve – A valve that allows air into a pipeline to prevent vacuum conditions when the pipeline is draining or during a sudden pressure drop. Helps prevent pipe collapse or damage.
Valve Stem – The shaft that transmits motion from the actuator to the internal valve components.
Venturi Valve – A valve designed to control flow using the Venturi effect (constriction to accelerate flow and reduce pressure).
V-Port Ball Valve – A ball valve with a V-shaped notch in the ball, allowing for improved flow control and throttling capabilities. Used in applications requiring more precise flow regulation than standard ball valves.
Wall Valve – A valve specifically designed to be mounted on the end of a wall pipe.
Wedge Gate Valve – A type of gate valve with a wedge-shaped disc for tighter shut-off.
INDUSTRY STANDARDS
ANSI – American National Standards Institute; sets many valve design standards.
API – American Petroleum Institute; defines valve performance standards.
ASME – American Society of Mechanical Engineers; sets mechanical and piping standards.
Factory Acceptance Test (FAT) – Testing performed before shipment to ensure the valve meets design requirements.
Fire Test Certification (API 607/6FA) – Indicates fire-tested valves.
Fugitive Emissions Test – Measures stem sealing leakage, especially for environmental compliance (e.g., API 622).
ISO - The International Organization for Standardization that develops and publishes international standards.
ISO 5211 – International standard for actuator mounting.
Leakage Class – Defined by ANSI/FCI 70-2 standards, such as Class II–VI (Class VI is bubble-tight).
NACE Compliance – Ensures material compatibility with sour gas (H2S) environments.
Site Acceptance Test (SAT) – Testing performed at the installation site to ensure proper function.
