Solenoid Valve Terminology

A | B | C | D | E | F | G | H | I | J | K | L | M | N

O | P | Q | R | S | T | U | V | W | X | Y | Z

 

A
AC  

Alternating Current. Electrical current that reverses direction at a predetermined rate (typically 50 or 60 times per second). Household electrical system are alternating current.

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B
Back Pressure  

Back pressure occurs if the pressure on the outlet port side exceeds the pressure on the inlet port side. Most solenoid valves are not designed to hold backpressure.

 

Bi-Directional Valve  

A bi-directional valve allows fluid flow in both directions through the valve. If a valve is labeled as a 2-way valve, it does not mean that it is is also bi-directional.

 

Burst Pressure  

The maximum pressure which may be applied to a valve without causing external leakage. However, permanent damage may occur to internal component. The burst pressure is often multiple times the normal maximum pressure. (see also Proof Pressure)

 

Buzz  

A sound (vibration) associated with AC valves when the plunger is not staying in contact with the stop. (see also Shading Ring)

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C
Continuous Duty Coil  

A coil that can be energized continuously without overheating will receive continuous duty rating.

 

Current Drain  

Expressed in amperes. Indicates the amount of current flowing through the solenoid valves coil when energized.

 

Cycle Life  

The total life expectancy of a solenoid valve in terms of cycles. (one cycle is movement from closed to open to closed position, or viceversa for normally open solenoid valves).

 

Cv Factor  

Cv stands for Flow Coefficient. Some people refer to it as flow capacity. It is defined as the volume of water in US gallons per minute that flow through the valve with a pressure drop of 1 PSI.

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D
DC  

Direct Current. Current that only flows in one direction. Batteries produce direct current.

 

De-Energized  

The state of a valve where electrical current is not being applied to the coil.

 

DIN Connector  

A connector standardized by Deutsches Institut für Normung (DIN), the German national standards organization. (click Coil Info for more details)

 

Direct-Acting Valve  

In a direct acting valve, the solenoid plunger (or core) directly opens and closes an orifice inside the valve. Direct acting valves do not require any differential pressure to operate (i.e. the valve will operate from 0 PSI to its rated maximum pressure).

 

Duty Cycle  

The ratio of active time to total time. (usually indicates how long the valve can be energized with off cycles of specified length without overheating)

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E
Encapsulated (Molded) Coil  

The coil is encapsulated in epoxy or other suitable resin.

 

Energized  

A valve is energized when current is supplied to the coil.

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F

Flux Plate  

A steel plate located at the bottom of the coil assembly. The flux plate helps carry magnetic flux. Often serves also as a supporting member for the coil assembly.

 

Flow Direction  

Flow direction or path is the direction media must travel through the valve. The flow direction is usually indicated by an arrow pointing from the inlet port to the outlet port. (see Bi-Directional Valve for more information)

 

Flow Rate  

A measure of the volume of fluid moving past a given point in a given period of time. May be expressed in gallons-per-hour, gallons-per-minute, liters-per-hour etc.

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G
   

 

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H
Heat Rise  

The increase in the coils internal temperature caused by self-heating. The temperature difference is measured between de-energized and energized coil in constant ambient temperature. As the heat of the coil rises, a point will be reached where the heat dissipation rate equal the heat generation rate.

 

Hit and Drop (Pulse and Hold)  

A technique for reducing the power consumption of solenoids valves. A larger voltage (current flow) is required to energize a valve than is needed to keep the valve in the energized position

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I
Intermittent Duty Coil  

A coil that has a specified duty cycle. A continuous use of this coil would most likely result in overheating.

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J
   

 

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K
   

 

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L
Latching Valve  

A latching solenoid valve does not require current to stay in its energized position. Electrical energy is only consumed to open and close the valve, not to keep it in either of those positions. Latching valves are often used in battery powered applications (e.g. automatic faucets) as they only need a pulse power to change open/closed state of the valve.

 

Leakage, External  

An internal part of a valve leaking to the external part.

 

Leakage, Internal  

The leakage across the sealing entity of the valve (i.e. unwanted flow between the inlet and outlet ports). Some valves designs accept a certain amount of leakage. This is usually reported as cubic centimeters per minute.

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M
Manual Override  

A mechanical device that allows a manual opening/closing of the valve.

 

Media  

The substance that passes through the valve. Different media types include water, air, oil, gas etc.

 

Metering Device  

Metering devices allow manual adjustment of the amount of fluid flow through the valve.

 

Minimum Operating Pressure Differential (MOPD)

 

 

Pilot operated valves require a pressure differential to operate. These valves list a minimum operating pressure that is required between the inlet and outlet ports.

 

Molded (Encapsulated) Coil

 

 

The coil is encapsulated in epoxy or other suitable resin.

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N
Normally-Closed Valve  

The normal state of the valve is closed. The valve opens when the coil is energized and re-closes once the power is removed from the coil.

 

Normally-Open Valve  

The normal state of the valve is open. Once the coil is energized, the valve closes. Removal of the electrical power causes the valve to open.

 

NPT  

National Pipe Thread (click here for more information)

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O
Operator  

Operator is a solenoid valve (without the valve body) which is installed in a manifold. The manifold houses the the inlet and outlet ports and the orifice.

 

Orifice  

An opening through which media passes when flowing through a valve. The orifice is opened and closed to control the flow of media through the valve.

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P
Pilot-Operated Valve  

Pilot-operated valves utilize line pressure for operation. The solenoid plunger (or core) opens the pilot orifice, allowing pressure to the outlet port side of the piston or diaphragm. This unbalanced pressure opens the valve. Pilot operated valves require a minimum pressure differential to operate and will not operate down to 0 PSI.

 

Pinch Valve  

A device used to pinch and unpinch flexible tubing for the purpose of controlling flow.

 

Plunger (a.k.a. Solenoid Core)  

The moving component of a linear solenoid which opens and closes the valve body orifice or pilot orifice for pilot operated valves.

 

Plunger Seal  

The seal or material at the end of the plunger.

 

Port, Inlet  

The media (fluid or gas) from the source enter the valve through the inlet port.

 

Port, Outlet  

Themedia (fluid or gas) from exits the valve through the outlet port.

 

Power Consumption  

The electrical energy required over time that must be supplied to the coil to maintain its operation. Typically expressed as Watts.

 

Pressure  

The force per unit area applied on a surface in a direction perpendicular to that surface. Usually expressed as pounds per square inch (PSI).

 

Pressure Drop/Pressure Differential

 

 

Pressure drop is a term used to describe the change in pressure across a system.

 

Pressure Head  

The height of the column of fluid which produces pressure. The height and the specific gravity are the only variables affecting the pressure caused by the fluid head. The shape and the volume of the fluid has no effect over the pressure.

 

Proof Pressure  

The level of pressure at which the valve will not yield during application of internal pressure. The internal parts will not be damaged at pressures at or below the proof pressure. Normally 1.5 times working pressure. (see also Burst Pressure)


PSI  

Pounds per square inch. The standard measurement for pressure in the United States. Normal atmospheric pressure at sea level is 14.7 PSI.

 

PSIA  

PSI (absolute). Gauge pressure plus barometric or atmospheric pressure.

 

PSIG  

PSI (gauge). Pressure referenced to ambient air pressure.

 

Pulse and Hold (Hit and Drop)  

A technique for reducing the power consumption of solenoids valves. A larger voltage (current flow) is required to energize a valve than is needed to keep the valve in the energized position.

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Q
   

 

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R
Rated Pressure  

The maximum allowable operating pressure.

 

Rectifier  

An electrical device for converting alternating current to direct current.

 

Response Time  

The time it takes the valve's operating mechanism to move from closed to open or open to closed position.

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S
SCFM  

The cubic feet of per minute of gas measured at standard conditions (70° F and 14.7 PSIG - Sea Level).

 

SCFH  

The cubic feet of per hour of gas measured at standard conditions (70° F and 14.7 PSIG - Sea Level).

 

Servo Operated Valve   See Pilot Operated Valve.
Shading Ring  

A copper or silver component inserted in the stop of an AC valve to minimize the oscillation or hum associated with AC valves.

 

Solenoid Valve  

An electro-mechanical device used for controlling the flow of media. Click here for a detailed definition.

 

Spring Loaded Plunger  

Indicates that the valve has a plunger return spring. Usually a sign that the valve may be mounted in any position.

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T
Tape Wrapped Coil  

A coil where the windings are wrapped with electrical tape as the final insulation layer.

 

Total Separation (Isolation) Solenoid Valve

 

 

A valve where the media is is in contact only with the valve body and the isolation lever or diaphragm.

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U
   

 

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V
VAC  

Volts - Alternating Current (see AC for more details)

 

Vacuum  

A pressure less than atmospheric pressure. A high vacuum is a pressure that is approaching zero pressure.

 

VDC  

Volts - Direct Current (see DC for more details)

 

Valve Body  

The portion of the valve that contains the inlet and outlet ports. It can be made out of plastic, brass, steel, stainless steel etc.

 

Valve Coil  

Single or multiple-turn winding of a conductor such as copper wire. The coil produces the magnetic field which in turn moves the valve plunger. (see also encapsulated (molded) coil and tape wrapped coil)

 

Viscosity   The measure of resistance to flow or "stickiness" of a fluid. The higher the viscosity, the higher the flow resistance.

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W
Watt  

A unit of electrical power, equal to the power developed in a circuit by a current of one ampere flowing through a potential difference of one volt.

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X
   

 

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Y
   

 

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Z
   

 

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