| 2/2 valve |
A type of two-way directional control valve with two ways and two positions. 2/2 valves most frequently are used to only block or allow fluid flow. |
| 3/2 valve |
A directional control valve with three ways and two positions. A 3/2 valve can be either mixing valve or a diverting valve. |
| 4/2 valve |
A directional control valve with four ways and two positions. In a 4/2 valve, one port is usually open to flow from the pump. |
| 4/3 valve |
A directional control valve with four ways and three positions. In a 4/3 valve, the three positions are normal, straight, and cross way. |
| actuation |
The act of performing a valve function. Actuation is the point at which a valve is triggered. |
| actuator |
A component that directly helps convert fluid energy into mechanical energy. Actuators can be such components as cylinders, motors, or rotary devices. |
| adjustable cap |
A relief valve component that controls the resistance on the pressure spring. Adjustable caps are tightened or loosened to adjust the amount of resistance against the spring. |
| adjusting screw |
A valve component that opens and closes to provide control capability to a valve. When the adjusting screw is unscrewed the valve is open, and when it's fully tightened the valve is closed. |
| air receiver |
An air storage tank used with pneumatic systems. An air receiver balances air compressor capacity and airflow demand. |
| air-piloted directional control valve |
A type of directional control valve that actuates using compressed air coming from the pilot port. Air-piloted directional control valves are sometimes used in pneumatic systems. |
| bleed-off circuit |
A flow-control configuration in which the flow control valve exhausts air when actuated. In a bleed-off circuit, the flow control valve can be located anywhere along the main line. |
| blow-off pressure |
The point at which the internal pressure of a pneumatic system triggers a relief valve. Blow-off pressure is also called cracking pressure. |
| cam-operated directional control valve |
A type of directional control valve that actuates using the distinct physical geometry of a cam. In cam-operated directional valves, cam rotation actuates the valving mechanism of the valve. |
| check valve |
A type of directional control valve that allows air to flow in only one direction. Check valves include in-line check valves and right-angle check valves. |
| compressed |
To be squeezed or pressed together into a smaller space. Compressed air is used by pneumatic systems to do work. |
| compressor |
A component that pressurizes ambient air. Compressors direct air into a pneumatic system after pressurizing it. |
| cracking pressure |
The point at which the internal pressure of a pneumatic system triggers a relief valve. Cracking pressure is also called blow-off pressure. |
| cylinder |
A type of linear actuator that uses a piston to produce motion in a straight line. Cylinders physically contact a valving element to change its position during mechanical actuation. |
| diaphragm |
A spring-loaded valve mechanism that moves in response to variations in pressure in a pneumatic system. The diaphragm is a flexible membrane that responds to changes in pressure and moves the poppet. |
| diaphragm-type regulating valve |
A type of pneumatic regulating valve with a spring-tensioned diaphragm as the main valving element. In a diaphragm-type regulating valve, air pushes against the diaphragm, a poppet closes the inlet to the valve, and as air pressure against the diaphragm decreases, the poppet opens the inlet. |
| diaphragm-type regulating valve |
A type of pneumatic regulating valve with a spring-tensioned diaphragm as the main valving element. In a diaphragm-type regulating valve, as air pushes against the diaphragm, a poppet closes the inlet to the valve, and as air pressure against the diaphragm decreases, the poppet opens the inlet. |
| directional control valve |
A fluid system component that determines the path air takes in a pneumatic system. Directional control valves are used to move actuators into various positions. |
| direct-operated |
A type of check valve. Direct-operated valves are actuated by compressed air pressing directly on the valving element. |
| electrical actuation |
The act of tripping or seating a valving element using an electrical device, such as a solenoid. Electrical actuation allows automated or remote-controlled valve operation. |
| exhaust port |
The port in a valve that allows excess pressure to escape. Exhaust ports are often covered by a ball attached to a spring that seals the port until excess pressure triggers the ball to unseal the port and allow the pressure to be released into the atmosphere. |
| flow |
The directional movement of air in a pneumatic system. Flow causes an actuator to move and perform work. |
| flow control valve |
A fluid system component that controls the rate of air flow. Flow control valves make it possible to control the speed of the actuator. |
| flow rate |
A specification of a compressor that indicates how much air a compressor can move in a certain amount of time. Flow rate for pneumatic pumps is measured in cubic feet per minute, or cubic meters per minute. |
| four-way valve |
A directional control valve. A four-way valve is typically used for double-acting actuators. |
| gripper |
A double-acting linear actuator. A gripper has the capability to repeatedly clamp and release. |
| inlet port |
An opening on the side of a compressor. The inlet port draws fluid into the system. |
| in-line |
A type of check valve that has the inlet and outlet ports located directly opposite each other. In in-line check valves, air flows through the valve in a straight line. |
| kilopascal |
A unit used to measure pressure in the SI system, abbreviated as kPa. Kilopascal is a measurement used to determine operating pressure in a pneumatic system. |
| limit switch |
A mechanical switch that halts further motion of the object that triggered the switch. A limit switch allows operators to remotely control an actuator. |
| lunging |
A situation in which the actuator and the load are moving in the same direction. Lunging, or overrunning, often causes an actuator to jump suddenly. |
| manual actuation |
The act of tripping or seating a valving element by hand. Manual actuation uses handles or cranks. |
| mechanical actuation |
The act of tripping or seating a valving element using the physical movement of machine components. Mechanical actuation employs a device, such as a plunger or cylinder. |
| meter-in circuit |
A flow-control configuration in which the flow control valve is located between the actuator and the compressor. Meter-in circuits control the amount of flow to the actuator. |
| meter-out circuit |
A flow-control configuration in which the flow control valve is located at the outlet of the actuator. Meter-out circuits control the amount of fluid leaving the actuator. |
| needle valve |
A type of flow control valve that adjusts the flow of air between and including fully on and fully off. Needle valves consist of a sharp conical obstruction that extends or retracts to block or allow flow. |
| one-way valve |
A directional control valve that allows air to move in only one direction. One-way valves are most commonly check valves with a ball-type poppet. |
| operating pressure |
The amount of pressure nearest the point of performing work at the output end of a fluid system. The operating pressure is used to specify the capability of valves and actuators. |
| overpressure |
A situation in which the pressure in a pneumatic system exceeds manufacturer recommended levels. Overpressure can lead to equipment damage and personal injury but can be controlled by a relief valve. |
| override |
A means of bypassing the essential function of a device, such as a valve. Overrides exist for various exceptions that can occur during normal operation. |
| pilot port |
A type of valve port. In a pilot port, the compressed air travels when actuating the pilot portion of a pilot-operated valve. |
| pilot signal |
A surge of fluid through the pilot port. Pilot signals actuate the pilot portion of a pilot-operated check valve. |
| pilot-operated |
A type of check valve. Pilot-operated check valves are actuated by compressed air coming from a pilot or ancillary port for the purpose of overriding a valve. |
| pilot-operated check valve |
A type of check valve that has an additional port for a pressure signal. Pilot-operated check valves allow operators to override normal check valve operation. |
| pilot-to-close check valve |
A type of check valve. Pilot-to-close check valves allow fluid to flow in the forward direction and stop flow in the reverse direction under normal circumstances. |
| pilot-to-open check valve |
A type of check valve. Pilot-to-open check valves allow fluid to flow in the reverse direction by opening the poppet when needed. |
| piston |
A rod inside a cylinder that is moved by pneumatic pressure. A piston is contained by a cylinder. |
| piston-type regulating valve |
A pneumatic regulating valve with a spring-tensioned, cup-shaped piston as the main valving element. In a piston-type regulating valve, air pressure from the inlet and pressure from the piston act against each other, allowing only a predetermined level of pressure to leave the valve. |
| pneumatic actuation |
The act of tripping or seating a valving element using compressed air. Pneumatic actuation trips a valve when a valving element detects a lack of air pressure. |
| pneumatic system |
A power transmission system that uses the force of flowing gases to transmit power. Pneumatic systems most commonly use air to transmit power. |
| poppet |
A valve mechanism that continually opens and closes in response to variations in pressure. The poppet is attached to a spring-loaded diaphragm. |
| ports |
An opening on a valve through which fluid can flow; can also be called ways. Ports allow air into and out of a pneumatic system. |
| positions |
The number of physical settings on a directional control valve. Valves can have two or more positions. |
| pounds per square inch |
psi. An English system unit of pressure. Pounds per square inch measures the amount of force that is applied over an area of one square inch. |
| power |
The rate at which work is accomplished. Power is expressed in foot-pounds (ft-lb) or newton-meters (N-m) and is the result of the amount of work accomplished divided by the time it took to do the work. |
| pressure differential |
The pressure from a load on an actuator minus the cracking pressure of a valve. Pressure differential is also called pressure drop and represents the difference between two pressure levels. |
| pressure drop |
The pressure from a load on an actuator minus the cracking pressure of a valve. Pressure drop is also called pressure differential and represents the difference between two pressure levels. |
| pressure switch |
A mechanism that regulates pressure in an air receiver. Pressure switches are actuated by a change in pressure. |
| programmable logic control |
PLC. A processor-driven device that uses logic-based software to provide electrical control to machines. Programmable logic control can electrically activate directional control valves. |
| regulating valve |
A pneumatic power device that protects the system against overpressure. Regulating valves are sometimes called reducing valves. |
| regulating valves |
A pneumatic power device that protects the system against overpressure. Regulating valves are sometimes called air regulating valves or reducing valves. |
| relief valve |
A component that allows pressurized air to escape a pneumatic system when the system pressure reaches a critical pressure. Relief valves prevent excess pressure from damaging a pneumatic system or causing bodily injury. |
| resistance |
The opposition to a force. Resistance can include a variety of factors, such as the weight of a load or friction during movement. |
| right-angle check valve |
A type of check valve that has the inlet and outlet located at right angles to each other. Right-angle check valves have a higher flow capacity than in-line check valves. |
| sequence valve |
A pneumatic valve that allows air into a secondary system. Sequence valves activate after a set pressure is reached. |
| solenoid |
A coil of wire that generates an electromagnetic force when a current is applied. When activated, solenoids can open and close valves. |
| spool |
A valve that controls the direction of pneumatic flow. A spool valve consists of cylindrical spool that alternately blocks and opens channels in the pneumatic system. |
| spring |
A device that yields under a compressive force and returns to its original shape once the force is removed. A spring is used as part of the sealing element in a regulating valve. |
| tapered head |
A head of a valve that gradually changes diameters. Tapered heads are found on needle valves. |
| threaded plunger |
The base of a needle valve that allows the valve to be screwed or unscrewed to adjust the opening. Needle valves are controlled manually. |
| three-way valve |
A directional control valve. A three-way valve diverts flow between two possible paths. |
| two-way valve |
A type of directional control valve with two ports: one inlet and one outlet. Two-way valves do not have an exhaust and usually only allow fluid to flow in one direction. |
| valves |
A mechanical device that controls air in a pneumatic system. Valves include two-, three-, and four-way directional valves. |
| ways |
An opening on a valve through which fluid can flow; can also be called ports. Ways allow air into and out of a pneumatic system. |
| work |
The result of a force applied to an object and the distance through which the force is applied. In an equation, work is force multiplied by distance. |
| working pressure |
The pressure rating that indicates the maximum pressure a conductor should experience in service. Working pressure is often called maximum allowable working pressure (MAWP). |