FEEDBACKA transfer of energy from the output of a device to its input.

FILTERA device whose primary function is the retention by a porous media of insoluble contaminants from a fluid.

FILTER ELEMENTThe porous device that performs the actual process of filtration.

FILTER MEDIAThe porous materials that perform the actual process of filtration.

FILTER MEDIA, SURFACEPorous materials that primarily retain contaminants on the influent face.

FLASH POINTThe temperature to which a liquid must be heated under specified conditions of the test method to give off sufficient vapor to form a mixture with air that can be ignited momentarily by a specified flame.

FLOW, LAMINARA flow situation in which fluid moves in parallel layers (also referred to as streamline flow).

FLOW, METEREDFlow at a controlled rate.

FLOW, TURBULENTA flow situation in which the fluid particles move in a random manner.

FLOW RATEThe volume, mass, or weight of a fluid passing through any conductor per unit of time.

FLOWMETERAn instrument used to measure quantity or the flow rate of a fluid motion.

FLUID FLOWThe stream or movement of a fluid, or the rate of its movement.

FLUID FRICTIONFriction due to the viscosity of fluids.

FLUID, FIRE-RESISTANTA fluid difficult to ignite, which shows little tendency to propagate flame.

FEEDBACKA transfer of energy from the output of a device to its input.

FILTERA device whose primary function is the retention by a porous media of insoluble contaminants from a fluid.

FILTER ELEMENTThe porous device that performs the actual process of filtration.

FILTER MEDIAThe porous materials that perform the actual process of filtration.

FILTER MEDIA, SURFACEPorous materials that primarily retain contaminants on the influent face.

FLASH POINTThe temperature to which a liquid must be heated under specified conditions of the test method to give off sufficient vapor to form a mixture with air that can be ignited momentarily by a specified flame.

FLOW, LAMINARA flow situation in which fluid moves in parallel layers (also referred to as streamline flow).

FLOW, METEREDFlow at a controlled rate.

FLOW, TURBULENTA flow situation in which the fluid particles move in a random manner.

FLOW RATEThe volume, mass, or weight of a fluid passing through any conductor per unit of time.

FLOWMETERAn instrument used to measure quantity or the flow rate of a fluid motion.

FLUID FLOWThe stream or movement of a fluid, or the rate of its movement.

FLUID FRICTIONFriction due to the viscosity of fluids.

FLUID, FIRE-RESISTANTA fluid difficult to ignite, which shows little tendency to propagate flame.

GAUGEAn instrument or device for characteristic. measuring, indicating, or comparing a physical

GAUGE PRESSUREPressure above atmospheric pressure.

GAUGE SNUBBERA device installed in the line to the pressure gauge used to dampen pressure surges and thus provide a steady reading and a protection for the gauge.

GAUGE, BELLOWSA gauge in which the sensing element is a convoluted closed cylinder. A pressure differential between the outside and the inside causes the cylinder to expand or contract axially.

GAUGE, BOURDON TUBEA pressure gauge in which the sensing element is a curved tube that tends to straighten out when subjected to internal fluid pressure.

GAUGE, DIAPHRAGMA gauge in which the sensing element is relatively thin and its inner portion is free to deflect with respect to its periphery.

GAUGE, PRESSUREA gauge that indicates the pressure in the system to which it is connected.

GAUGE, VACUUMA pressure gauge for pressures less than atmospheric.

GRAVITYThe force that tends to draw all bodies toward the center of the earth. The weight of a body is the resultant of gravitational force acting on the body.

HEADThe height of a column or body of fluid above a given point expressed in linear units. Head is often used to indicate gauge pressure. Pressure is equal to the height times the density of the fluid.

HEAD, FRICTIONThe head required to overcome the friction at the interior surface of a conductor and between fluid particles in motion. It varies with flow, size, type, and condition of conductors and fittings, and fluid characteristics,

HEAD, STATICThe height of a column or body of fluid above a given point.

HEAD, VELOCITYThe equivalent head through which the liquid would have to fall to attain a given velocity. Mathematically it is equal to the square of the velocity (in feet) divided by 64.4 feet per second square.

HEAT EXCHANGERA device that transfers heat through a conducting wall from one fluid to another.

HYDRAULICSEngineering science pertain-ing to liquid pressure and flow.

HYDROMETERAn instrument for deter-mining the specific gravities of liquids.

HYDROPNEUMATICSPertaining to the combination of hydraulic and pneumatic fluid power.

HYDROSTATICSEngineering science pertaining to the energy of liquids at rest.

IMPACT PRESSUREThe pressure of a moving fluid brought to rest that is in excess of the pressure the fluid has when it does not flow; that is, total pressure less static pressure. Impact pressure is equal to dynamic pressure in incom-pressible flow; but in compressible flow, impact pressure includes the pressure change owing to the compressibility effect.

IMPINGEMENTThe striking or dashing upon with a clash or sharp collision, as air impinging upon the rotor of a turbine or motor.

IMPULSE TURBINEA turbine driven by a fluid at high velocity under relatively low pressure.

INERTIAThe tendency of a body at rest to remain at rest, and a body in motion to continue to move at a constant speed along a straight line, unless the body is acted upon in either case by an unbalanced force.

INHIBITORAny substance which slows or prevents chemical reactions such as corrosion or oxidation.

INVERSE PROPORTIONThe relation that exists between two quantities when an increase in one of them produces a corresponding decrease in the other.

KELVIN SCALEThe temperature scale using absolute zero as the zero point and divisions that are the same size as centigrade degrees.

KINETIC ENERGYThe energy that a substance has while it is in motion.

KINETIC THEORYA theory of matter that assumes that the molecules of matter are in constant motion.

LINEA tube, pipe, or hose that is used as a conductor of fluid.

LIQUIDA form of matter that has a definite volume but takes the shape of its container.

LOADThe power that is being delivered by any power-producing device. The equipment that uses the power from the power-producing device.

LUBRICATORA device that adds controlled or metered amounts of lubricant into a fluid power system.

MANIFOLDA type of fluid conductor that provides multiple connections ports.

MANOMETERA differential pressure gauge in which pressure is indicated by the height of a liquid column of known density. Pressure is equal to the difference in vertical height between two connected columns multiplied by the density of the manometer liquid. Some forms of manometers are U tube, inclined tube, well, and bell types.

MATTERAny substance that occupies space and has weight.

MECHANICAL ADVANTAGEThe ratio of the resisting weight to the acting force. The ratio of the distance through which the force is exerted divided by the distance the weight is raised.

METER-INTo regulate the amount of fluid into a system or an actuator.

METER-OUTTo regulate the flow of fluid from a system or actuator.

MICRONA millionth of a meter or about 0.00004 inch.

MOLECULEA small natural particle of matter composed of two or more atoms.

MOTORA device that converts fluid power into mechanical force and motion. It usually provides rotary mechanical motion.

MOTOR, FIXED-DISPLACEMENTA motor in which the displacement per unit of output motion cannot be varied.

MOTOR, ROTARYA motor capable of continuous rotary motion.

MOTOR, ROTARY LIMITEDA rotary motor having limited motion.

MOTOR, VARIABLE-DISPLACEMENT A motor in which the displacement per unit of output motion can be varied.