Glossary of Terms

Dixon offers the following alphabetical listing of terminology commonly found in the manufacturing industry.

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3A Symbol for 3A Sanitary Standards Symbol Administrative Council. The 3A Sanitary Standard was created by the dairy industry as a voluntary benchmark for product performance and sanitary safety. The standard, collaboratively developed by a group of processors, suppliers, regulatory officials and sanitation specialists, is accepted by federal, state and local regulatory authorities. Our products have earned the 3A symbol through third party verification. This assessment makes certain each product conforms in all aspects to the published standards. Dixon Sanitary is proud to be a participant in the 3A program.
3A Finish Product surface finish equivalent to 150 grit or better OD, and 180 grit or better ID. A minimum of Ra 32 micro inch (0.8 micron) is indicated.
A.N.S.I. American National Standards Institute, Inc.
A.P.I. American Petroleum Institute
A.S.A. American Standards Association
A.S.M.E. American Society of Mechanical Engineers
A.S.T.M. American Society for Testing and Materials
ABS (Acrylicnitrile-butadiene-styrene) a thermoplastic resin with an excellent resistance to acids, bases, salts and some solvents. It is heat-resistant to 230°F.
Absolute Pressure A measure of pressure having it’s zero point at atmospheric pressure. For example, the sum of atmospheric and gauge pressure would be absolute pressure (PSIA). For vacuum, it is expressed in inches of mercury.
AC Alternating current.  The form in which electricity is delivered to businesses and residences.
Accidental Disconnection Disconnection of a coupling while in operation due to failure of the coupling mechanism (a.k.a. unintentional disconnection).
Accumulator A container in which fluid is stored under pressure as a source of reserve fluid power.
Acme Thread A flat grooved helical ridge on a nut or bolt. This thread typically has a 29° included angle and is used on bevel seat and John Perry fittings.
Adapter The grooved portion of a cam & groove coupling.  Also, a fitting that converts from one type or size to another type or size.
Adapter Connects the pump fluid end to the motor
Aeration Air in a fluid
Affinity Laws Used to predict how capacity, head and horsepower are affected by changes in the centrifugal pump impeller diameter or impeller speed.
Air Inclusion The air forced into the system during the connection of a quick disconnect coupling.
Air Receiver Manifold A tank that is connected to a compressor via a Bull Hose. It has multiple outlets so several pneumatic tools can operate simultaneously.  An Air Receiver Manifold must have an A.S.M.E. build certification plate attached to comply with OSHA regulations.
Ambient Temperature The temperature at a point or area expressed as an average of the surrounding areas or materials.  Ambient surface temperature is generally given to be 70°F to 80°F – an average of daily and seasonal variations.
Anneal Stress relief of stainless steel, a heat treatment to remove the stresses generated in forming and welding operations. This heat treatment is best done under a controlled atmosphere or vacuum to maintain the mill finish. The fittings are not quenched, as in solution annealing; this would reintroduce residual stresses. Done correctly, parts are processed to provide minimum residual stresses and full corrosion resistance.
Anodize A process for aluminum, like zinc or chrome plating steel, in which an aluminum part is electrically charged then dipped in various chemicals to produce various colors and / or surface hardness.
ANSI American National Standards Institute, Inc.
Armored Hose A protective covering, applied as a braid or helix, to protect the hose from physical abuse.
ASME American Society of Mechanical Engineers
Assembly A reference to a hose having couplings installed in one or both ends.
Assembly Pressure Rating The pressure rating (in PSI) of the lowest rated component whether it be the hose or couplings.
ASTM American Society for Testing and Materials
Atmospheric Pressure Pressure exerted by the atmosphere at any specific location. Sea level pressure is approximately 14.7 PSI.
Atmospheric Pressure Force per unit area exerted against a surface by the weight of the air above that surface.  At sea level, atmospheric pressure is 14.7 PSI.
Attachment The method or process for securing a coupling to a hose.  Example: banding, clamping, swaging, crimping.
Autoclave A pressure vessel used for vulcanizing rubber products by means of steam under pressure.
Automatic Welding Welding with equipment that performs the welding operation without adjustment of the controls by a welding operator.  The equipment may or may not perform the loading and unloading of the work  (see also machine welding).
B.S.P.P. British Standard Pipe Parallel thread.
B.S.P.Tr. British Standard Pipe Taper thread. 
Backpressure Refers to pressure existing on the discharge side of a system.
Bar An international standard unit of pressure equal to 100,000 Pascals, approximately 14.5 PSI.
BEP Best Efficiency Point The point where the power coming out of the pump (water horsepower) is the closest to the power coming into the pump (brake horsepower) from the motor.  This is also the point where there is no radial deflection of the shaft caused by unequal hydraulic forces acting on the impeller.  Referred to as the sweet spot on the curve.
Bevel Seat Ferrules A set of plain (male) and externally threaded (female) bushings with matching bevel angles that produce a leak-proof seal when connected with a hex union nut. The threads used are Acme form.
BHP Brake Horsepower.  The actual amount of horsepower being consumed by the pump as measured on a pony brake or dynamometer.  This is not the horsepower used by the motor or driver.
Bioprocessing The creation of a product utilizing a living organism
Bioprocessing Equipment Equipment, systems or facilities used in the creation of products utilizing living organisms
Blind-Mate A coupling that can be automatically connected without human intervention and without visibility.
Blister A raised area or separation between hose layers creating a void or air-filled space.  Can be visible on either the hose cover or the hose tube.
Bolt Hole Circle A circle on the flange face around which the center of the bolt holes are distributed.
Bowl The exterior shell of an expansion ring type coupling.
Braid A continuous sleeve of interwoven single or multiple strands of material.  In hose construction, these strands are usually textile or metal.
Braid Angle The angle at the intersection of a braid strand and a line parallel to the axis of a hose.
Break-Away Automatic disconnection of a coupling when an axial separation force is applied.
Bright Anneal Annealing in a protective medium to prevent discoloration of the surface.
Bright Annealed Finish A silvery satin surface, approximately the mill finish of stainless steel.
Brinelling Dimples or grooves worn into the shoulder of a male half by locking balls in the female half. This is terminology stemming from a test that is done to evaluate the hardness of metals.
Buffing Grinding or removing surface material to obtain dimensional conformance.
Bull Hose Typically, a large diameter air hose that connects a compressor to an Air Receiver Manifold
Buna Synthetic rubber, a copolymer of acrylonitrile and butadiene.
Burst A rupture caused by internal pressure.
Burst Pressure The pressure at which rupture occurs.
Burst Pressure The pressure at which rupture occurs.
Capacity Flow rate normally measured in gallons per minute (GPM).
Carbon/Graphite A common mechanical seal face material chemically inert to most fluids with the exception of oxidizers, bleaches, halogens and a few other fluids.
Carcass The fabric, cord and/or metal reinforcing section of a hose as distinguished from the hose tube or cover.
Case Hardening Hardening the entire surface of a low carbon steel to a specific depth.
Cavitation A localized gaseous condition within a liquid stream which occurs where the pressure is reduced to the vapor pressure.
Cavitation When the NPSH required by the pump is greater than the NPSH available by the system, cavitation occurs. Vapor is formed and moves along with the stream. These vapor bubbles or "cavities" collapse when they reach regions of higher pressure on their way through the pump cavities. When these cavities form at the suction of the pump, several things happen all at once.
•  We experience a loss in capacity.
•  We can no longer build the same head (pressure)
•  The efficiency drops.
• The cavities or bubbles will collapse when they pass into the higher regions of pressure causing noise, vibration, and damage to many of the components.
CCW Counter clockwise
Centipoise Metric unit of viscosity
Centistoke The kinematic unit of viscosity.  Viscosity in centipoise divided by the liquid density at the same temperature gives kinematic viscosity in centistokes.
Centrifugal Pump Moves liquid with centrifugal force.
Ceramic A hard, chemically inert seal face material that has very high compressive resistance.
C-Face/Frame The NEMA standard for motor mounting dimensions.
Chamfer To cut an angle on the hose tube aid in stem insertion and to prevent the hose end from flaring when a stem is inserted.
Charge Pressure The pressure at which replenishing fluid is forced into the hydraulic system (above atmospheric pressure).
Check Valve A valve which permits flow of media in one direction only.
Checking See “Crazing”.
Clamp A metal fitting, band or wire used around the outside of a hose end to secure a coupling, fitting or nipple.
Clamp A device used to join mechanical parts, fittings, ensuring a quick leak-proof connection and enabling easy take down.
Clean-In-Place (CIP) Internally cleaning a piece of equipment without relocation or disassembly.  The equipment is cleaned but not necessarily sterilized.  The cleaning is normally done by acid, caustic or a combination of both with water-for-injection (WFI) rinse.
Close Coupled The pump impeller is mounted directly to the motor shaft or stub shaft that is mounted directly on the motor shaft.  There is no separate bearing case.
Cold Flow Continued deformation or movement under stress.
Cold Flow Continued deformation under load.
Cold Flow Continued deformation or movement of rubber or PTFE under stress.
Compression Set The deformation which remains in rubber after it has been subjected to and released from stress such as a clamp.  The longer the stress is maintained the more definitive the deformation.
Compression Set The deformation that remains in rubber or PTFE after it has been subjected to and released from stress such as a clamp. The longer the stress is maintained the more definitive the deformation.
Connect Under Pressure The ability to connect coupling halves with internal line pressure applied to either both sides or one side.
Contamination Any material foreign to a media that has a harmful effect on its performance in a system.
Controlled Sulfur In weld ends of 316L materials used in BPE installations, the sulfur content must be between .005% and .017% to assure better orbital welding.
Corrosion A chemical or electrochemical interaction between a metal and its environment, which results in changes in the property of the metal.  This may lead to impairment of the function of the metal, the environment and/or the technical system involved.
Corrugated Hose Hose with an exterior that is radially or helically grooved to enhance flexibility and/or reduce weight.
Coupling A devise at the end or ends of a length of hose that allows a connection to be made.
Coupling, Female Half a.k.a. coupler, socket, receiver
Coupling, Male Half a.k.a. nipple, plug, adapter
Cover The outermost part of the hose.  The main purpose for the hose cover is to protect the hose reinforcement form physical and environmental abuse.  Covers can have materials (rubber compounds) that are blended to produce characteristics such as ozone resistance, abrasion resistance or oil resistance.
Cracking A sharp break or fissure in the hose surface.  Usually caused by stress, flexing and/or environmental conditions.
Crazing A surface effect on hose characterized by multi-directional minute cracks.
Crimp Diameter The finished dimension that a ferrule or sleeve to which is reduced.
Crimping The act of forming the metal sleeve or ferrule of a hose fitting with a surrounding series of die segments to compress the hose within the fitting.  The crimping process changes the shape of the entire circumference and length simultaneously.  Often interchanged with the term "swaged".
Cv The flow rate (in US gal/min) of pure water at 60°F passing through a valve when the valve is fully opened and the pressure differential between the two ends of the valve is 1 PSI.
•  V = max. flow (in US gal/min)
•  G = specific gravity (1 for water)
•  P1 = inlet side pressure (psi)
•  P2 = outlet side pressure (psi)
CW Clockwise
CWP Cold Working Pressure
Cycle See Hertz
DA Double acting
Date Code Any combination of letters, numbers or symbols to identify time and / or location of manufacture.
DC Direct current.  The movement of electrical charge is only in one direction.
Dead Head The condition of a centrifugal pump running with a closed discharge line.
Deflection The effect of crimping producing a change in shape or size of the stem.
Delrin® Registered trademark of E.I. duPont Nemours and Company.
Design Factor See “Safety Factor”
Differential Pressure  (DP) The difference in pressure between any two points of a system or a component, also known as Delta-P or pressure drop.
Dilatent Fluid Viscosity increases with shear.
Discharge Head The outlet pressure of a pump.
Double-Acting Any pneumatic actuator, which uses air to drive the actuator, output shaft in both the CW and CCW directions. The air supply is piped to one side of a piston-drive or a diaphragm while the air contained on the opposing side is exhausted.
Double-Acting Sleeve Permits push-to-connect and pull-to-connect convenience when female half is mounted on the sleeve.
Dovetail Extension The "fingers" on the sides of a clamp that interlock to prevent straight line leaks.
DPDT Double pole-double throw, a type of limit switch.
Dry Running Occurs when a pump is running with insufficient or no fluid in the pump.
Drybreak Coupling A coupling that allows connection and disconnection without spillage or air inclusion (a.k.a. flush face, flat face, no-spill)
Durometer An instrument for measuring the hardness of rubber.
Durometer An instrument for measuring the hardness of rubber.
Durometer Hardness A numerical value indicating the resistance to indentation or displacement of a probe.  The higher the value, the harder the material
Durometer Hardness A numerical value, which indicates the resistance to indentation of the blunt indentor of the durometer.
Dust Cap Dust or dirt repelling enclosure for the nipple.
Dust Plug Dust or dirt repelling enclosure for the coupler.
Dwell The amount of time the crimp dies are held in the closed position to eliminate the metal sleeve or ferrule attempting to return to its original diameter.
Dynamic Head (System Head) A moving fluid exerts a pressure higher than the static pressure due to the kinetic energy of the fluid.
Dynamic Pressure Pressure that, once it is released, is able to be immediately replenished.
Eccentric Wall In hose or tubing, a wall of varying thickness.
Eccentricity In hose, tubing or cylindrical articles, the condition resulting from the inside and outside diameters not having a common center.
Efficiency Power out of the pump divided by power into the pump.
Efficiency Formula: TDH X GPM / HP X 3960
Elastomer Any of various elastic substances resembling rubber.
Elastomer Any of various elastic substances resembling rubber.
Elastomeric Material A material that can be stretched or compressed repeatedly and, upon immediate release of stress, will return to its approximate original size.
Electric Actuator An electro-mechanical device used to open and close or modulate a valve. The actuator (which is mounted and coupled to the valve in similar fashion as the pneumatic actuator), operates the valve using an electric motor driving a gear train. While the basic function of the electric actuator is similar to the pneumatic, there are distinct differences in the application and flexibility of the two types, and these differences should be considered to select the proper type.
Electric Failsafe Actuator Electrically driven actuator that contains an internal spring to close the valve on loss of power.
Electropolishing A controlled electrochemical process utilizing acid electrolyte, DC current, anode and cathode to smooth the surface by removal of metal.
Encapsulation The enclosing of material by an encapsulant for protective purposes. In a ball valve, the ball is encased in PTFE, preventing the material flowing through the valve from getting behind the ball causing contamination problems.
EPDM Ethylene propylene diene monomer, a synthetic rubber.
Expansion Ring Typically refers to a type of fire hose couplings that are attached by expanding a sleeve (usually brass) outward to compress the hose against the wall of the bowl of the coupling.
External Swage (Swaging) A ferrule is passed through a reducing die, usually split, to bring the ferrule O.D. down to a pre determined size (for proper coupling retention) forcing the hose tube down into the stem serrations.
Eye of the Impeller The center of the impeller where the fluid enters.
F.D.A. Food and Drug Administration
Fail-Closed Spring Return pneumatic actuator is applied to the valve such that the spring will drive the valve to the close position upon loss of air (may be termed air-to-open).
Fail-Open Spring Return pneumatic actuator is applied to the valve such that the spring will drive the valve to the open position upon loss of air (may be termed air-to-close).
Ferrule A collar placed over a hose end to attach the fitting to the hose.  The ferrule may be crimped or swaged, forcing the hose against the shank of the coupling, or the shank may be expanded, forcing the hose out against the ferrule, or both.
Ferrule A bushing used to secure a tube joint. A special bushing designed for welding to the end of tubing. Two ferrules and a gasket make a leak-proof connection when used with the complimentary clamps.
Fitting See Coupling.
Fitting A small part of an apparatus (may be detachable).
FKM A DuPont manufactured elastomer widely used in the sealing industry.  FKM is the generic equivalent.
Flex cracking Surface condition directly related to repeated bending and straightening.
Flooded Suction When the liquid source is higher than the pump and the liquid flows to the pump by gravity.  Preferable for centrifugal pump installations.
Flow See capacity
Flow Checking Occurs when a valve closes during flow conditions, such as when quickly lowering a heavy implement (a.k.a. check off,back checking, lock-up).
Flow Coefficient (Cv) The flow in U.S. gallons of water (at 60°F) that will pass through the valve in one minute with a differential pressure across the valve of 1 PSI.
Fluid End The portion of the pump that comes in contact with the fluid being pumped.
Fluorocarbon Elastomer known as FKM a registered trademark of DuPont.
Fluoropolymer Polymer material having a carbon chain either partially or completely bonded to fluorine atoms. FKM (FKM) and PTFE are examples of this material type.
Flush Position (valve) A no-spill valve that allows connection and disconnection without spillage or air inclusion. (a.k.a. flush face, dry break, no-spill).
Foot Valve A type of check valve.  Used at the point of the liquid intake to retain liquid in the system, preventing the loss of prime when the liquid source is lower than the pump.
Force to Connect Axial and/or rotational force required to make a complete connection.
Force to Disconnect The reverse of the above.
Frame See C-Face
Free O.D. Hose Outside Diameter before stem is inserted.
Friction Head The pressure needed to overcome the resistance to the flow in the pipe and fittings.
Friction Loss The resistance to flow as a liquid is moved through a pipe (or valve); due to viscous shear stresses within the liquid and resulting turbulence.
G.P.M. Acronym for Gallons Per Minute, a measure of flow.
Gas Tungsten-Arc Welding (GTAW) An arc welding process that produces coalescence of metals by heating them with an arc between a tungsten (non-consumable) electrode and the work. Shielding is obtained from a gas or gas mixture.  (This process is sometimes called TIG welding, a non-preferred term.)  GTAW may be performed by adding filler material to the weld or by a fusion process in which no filler is added.
Gasket A seal used between matched machine parts to prevent escape of a gas or fluid. Special seals fit between the ferrules on the fittings, which are then clamped together, compressing the seal and making a leak-proof joint.
GPM Gallons per minute
Gripping Finger The part of the clamp that goes over and behind the stem collar to aid in clamp retention.
Grooved Fittings Typically refers to Victaulic grooved style couplings.  See Victaulic Groove.
Hard Coat An anodizing process in which the surface hardness of aluminum becomes similar to or greater than that of case hardened steel.
Hard Face A seal face either rotating or stationary.  The most common materials are silicon carbide, ceramic and tungsten carbide.
Head The equivalent height of the liquid. 20°C water is used as the standard where 33.9ft of water equals one atmosphere (14.7psi).  The pressure in a column of liquid. Pressure will increase as the height of the column increases.  Head refers to the height in feet: pressure refers to the PSI.  Centrifugal pump discharge is measured in head.
Heat Number An alphanumeric identification of a stated tonnage of metal obtained from a continuous melting in a furnace.
Heat-Affected Zone That portion of the base metal that has not been melted, but whose microstructure or mechanical properties have been altered by the heat of welding or cutting.
Helix A wire or other reinforcement material spiraled around the cylindrical body of a hose.
Hertz Frequency (cycles per seconds)
Hex Union Nut An internally acme-threaded six-sided connector used to assemble bevel seat fittings.
Hold Test Subjecting a hose to a specific hydrostatic pressure for a specific duration.
Horsepower Unit for measurement of power or rate of work.  One horsepower = 33,000 foot pounds per minute.
Hose A flexible conduit consisting of a tube, reinforcement and usually and outer cover.
Hose Assembly A length of hose with a coupling attached to one or both ends.
Hygienic Clamp Joint A tube outside diameter union consisting of two neutered ferrules having flat faces with a concentric groove and mating gasket that is secured with a clamp, providing a non-protruding, recessless product contact surface.
I.D. Inside Diameter
I.P.T. Iron Pipe Thread.  Also known as N.P.T. – National Pipe Taper thread.
I.S.O. International Standardization Organization.
Impact To strike with a mallet or hammer.
Impeller A rotor or rotor blade attached to the end of the stub shaft imparting energy from the motor to the fluid being pumped.
Impulse An application of force in a manner to produce sudden strain or motion such as pressure spikes.
Induction Hardening Induction Hardening
Internal Expansion A plug (or bullet) is pulled through a stem or a set of blades (fingers) increase the stem I.D. to the plug O.D. or a predetermined setting when using expansion blades (fingers). This forces the stem serrations into the hose tube and the hose cover into the serrations of the ferrule.
Internal Expansion (I.X.) (1) A plug (aka bullet) is pulled through a stem to increase the stem I.D. to the plug O.D.

(2) A finger expander increases the I.D. to a predetermined size or pressure setting.

Either process creates a “full flow” effect.

Investment Cast Also known as the “Lost Wax” process.  A wax mold that is an exact replica of the part to be produced is dipped in ceramic slurry.  When dry, the part is placed in an oven to harden the ceramic and melt out the wax.  From there the metal is poured to produce the desired part.
ISO5211 International standard for valve and actuator interface.
J.I.C. Joint Industrial Committee
J.I.C. Thread Typically refers to the threads on hydraulic fittings having 37° conical sealing surfaces.
Kalrez® Registered trademark of DuPont Dow Elastomers
Kamlock Another name for cam & groove couplings
Kinetic Energy Created by a centrifugal pump when the velocity of the fluid is accelerated to the outer rim of the impeller.  The amount of kinetic energy given to the fluid corresponds to the velocity at the impeller vane tip.  The faster the impeller revolves or the bigger the impeller, the greater the energy given to the fluid.  This kinetic energy is then harnessed and slowed by the resistance created by the pump volute.
Kinking A temporary or permanent distortion of the hose induced by bending beyond the minimum bend radius.
L.P.G. Liquefied Petroleum Gas.
Laminar Flow The flow of a fluid when each particle of the fluid follows a smooth path, paths that never interfere with one another. One result of laminar flow is that the velocity of the fluid is constant at any point in the fluid.
Leakage The media that is unintentionally released from a coupling due to component failure or retention weaknesses.
Leaker (1) A crack or hole in the tube which allows the media to escape;
(2) A hose assembly which allows the media to escape at the couplings.
LPM Acronym for Liters Per Minute, a measure of flow.
Lubricant Any fluid that will maintain a film thickness of one micron or more at its operating temperature and load.
M.A.W.P. Maximum Allowable Working Pressure
M.S.H.A. Mine Safety and Health Administration
Machine Welding Welding with equipment that performs the welding operation under the constant observation and control of a welding operator.  The equipment may or may not perform the loading and unloading of the works. (see also automatic welding).
Manual Override Any mechanical device by which an automated valve may be manually operated. On smaller actuators, this may simply be wrench flats on the output shaft of the actuator. Larger actuators may require a more sophisticated system, such as declutchable hand wheels, or manual gears.
Manual Welding Welding in which the entire welding operation is performed and controlled by hand.
Maximum-Shut-Off The pressure of the media flowing into the valve against which the valve will have to close.
Mean In the middle or average.
Meandering Of or pertaining to a weld bead that deviates from side to side across the weld joint rather than tracking the joint precisely. Note the controlled sulfur content in BPE weld material.
Mechanical Seal A positive sealing device used to seal all fluids.  Consists of two basic parts, a rotating element attached to the pump shaft and a stationary element attached to the pump casing. Each of these elements has a highly polished sealing surface.  The polished faces of the rotating and stationary elements come into contact with each other to form a seal that prevents leakage along the shaft.
Media Material (any material) being transported through a hose.
Media The material flowing through the system.
Minimum Burst Pressure The lowest pressure at which rupture occurs under prescribed conditions.
Modulating Service Proportional positioning of a valve between the open and closed positions, used for flow control processes.
MTR Material Test Report
N.H. Fire Hose thread. Same as N.S.T.
N.P.S. Same as N.P.S.M.
N.P.S.M. American Standard Straight Pipe Thread for Free Mechanical Joints.
N.S.T. Fire Hose thread.
NAMUR International Standard of Interface for Actuator Accessory Connections.
Necking Down A localized decrease in the cross-sectional area of a hose.  Also known as “Goose Necking”. 
NEMA 4 Weather-proof enclosure suitable for indoor/outdoor applications to protect from windblown dust, rain or hose-directed water.
NEMA 4x Offers the same protection as Nema 4 with the addition of corrosion resistance.
NEMA 6 Enclosure that may be submerged up to six feet for 30 minutes.
NEMA 7 Enclosure for hazardous locations must be capable of withstanding an internal explosion of gases so as not to ignite an external gas-air mixture.
NEMA Rating National Electrical Code Ratings for electrical component enclosures.
Neoprene Synthetic rubber, chemically and structurally similar to natural rubber.
Net Positive Suction Head Amount of energy in the liquid at the pump datum. It must be defined to have a meaning, as either available or required NPSH.
Nick A surface void anomaly caused by material removal or compression from the surface, whose bottom surface is usually irregular.
Nipple The section of the fitting that is inserted into the hose.  Also known as the shank of a coupling.
Nominal (1)A dimensional value assigned for the purpose of convenient designation.
(2) Average measurement.
Nominal Size A dimensional value assigned for the purpose of convenient designation, used for pipes.
NPSH(a) Net positive suction head available is the amount of fluid pressure you have at the suction side of the pump due to atmospheric pressure, pressurized tank or other means.
NPSH(r) Net positive suction head required is the amount of fluid pressure required at the suction to prevent cavitation. This requirement is found on pump curves produced by each pump manufacturer.
O.D. Outside Diameter
O.S. & D. Oil Suction and Discharge.
ODP Open Drip Proof motor enclosure
On-Off Service When the valve is being used to cycle to the full open or full closed position.
Operating Pressure The pressure at which system functions.  Also known as Working Pressure.
Operating Pressure The pressure at which a system is operated (a.k.a. working pressure).
Operating Pressure The pressure at which system functions. Also known as Working Pressure.
Orbital Welding Automatic or machine welding of tubes or pipe in-place with the electrode rotating (or orbiting) around the work.  Orbital welding can be done with the addition of filler material or as a fusion process without the addition of filler.
Ozone Cracking The surface cracks, checks or crazing caused by exposure to an environment containing ozone.
P.S.I. Pounds per square inch.
P.S.I.G. Pounds per square inch gauge.
Passivation Removal of exogenous iron or iron from the surface of stainless steels and higher alloys by means of a chemical dissolution, most typically by a treatment with an acid solution that will remove the surface contamination and enhance the formation of the passive layer.
Peak Pressure Maximum momentary pressure encountered in the operation of a component (a.k.a. pressure spike, surge pressure)
Permanent Fitting The type of fitting which, after it is applied, cannot be removed for reuse.
Permanent Set The amount by which an elastic material fails to return to its original form after deformation.
Phonograph Finish A series of small grooves cut into the surface of a shank to aid in coupling retention of hoses having hard tubes such as cross-linked polyethylene (XLPE) or ultra high molecular weight (UHMW).  Grooves resemble those on a phonograph record.
Pig An object forced, usually via air pressure, through the length of an assembly to clean out any residual product.
Pitch The distance from one point on a helix to the corresponding point on the next turn of the helix, measured parallel to the axis.
Pneumatic Actuator An air operated mechanical device used to open and close or modulate a valve. The actuator, which is mounted to the valve by a bracket and coupled to the stem, is designed to convert air pressure into mechanical force sufficient to operate the valve.
Pock Marks Uneven blister – like elevations, depressions or pimpled appearance.
Polish To make smooth and shiny by rubbing. Fittings may be machine polished to a 180 grit finish. Polish is ID, OD, or both per customer request.
Polymer A macromolecular material formed by the chemical combination of monomers having the same or different chemical composition.
Polypropylene A lightweight synthetic plastic.
Popcorn Common to steam hose.  Small eruptions within the tube rip or tear away material leaving cavities in the tube.
Positive Displacement Pump A pump that causes a fluid to move by trapping a fixed amount of it then forcing (displacing) that trapped volume into the discharge pipe.
Powder Coat A process in which electrically charged dry plastic powder paint is applied onto a metal surface or part.  The part is then baked in an oven resulting in a finished part that has a uniform and durable finish.  The only way to remove a powder coat finish is by sand blasting or burning.
Pressure The force per unit area applied on a surface in a direction perpendicular to that surface.
Pressure Cap A cap which incorporates a seal capable of withstanding the rated pressures on the male half.
Pressure Head Must be considered when a pumping system either begins or terminates in a tank which is under some pressure other than atmospheric. The pressure in such a tank must first be converted to feet of liquid. A vacuum in the suction tank or a positive pressure in the discharge tank must be added to the system head, whereas a positive pressure in the suction tank or vacuum in the discharge tank would be subtracted. The following is a handy formula for converting inches of mercury vacuum into feet of liquid.

Vacuum, in. of Hg X 1.13 / Vacuum, ft of liquid = Sp. Gr.

The above forms of head, namely static, friction, velocity, and pressure, are combined to make up the total system head at any particular flow rate.

Pressure Impulse Test Subjecting a component to a specified pressure at a specific rate of increase or decrease for a specified time limit and cycle
Pressure Rating Pressure at which a system is designed to operate, allowing for applicable safety factors.
Pricker Mark A perforation of the hose cover to allow pressure build – up between the sections of a hose to escape before these pressures can damage the hose.  Most common in steam hose.
Prime A charge of liquid required beginning the pumping action of centrifugal pumps when the liquid source is lower than the pump.
Profilometer An instrument for the measurement of the degree of surface roughness.
Proof Pressure A specified pressure which exceeds the hose assemblies rated working pressure to indicate its reliability at normal working pressure.  Follow R.M.A.’s testing guidelines for specific pressures and duration lengths for various types of hose.
Proof Pressure The nondestructive test pressure in excess of the maximum rated operating pressure, generally 1.5 times the standard
PSI Acronym for Pounds Per Square Inch, a measure of pressure.
PSI Pounds per square inch
PSIG Pounds per square inch gauge
PTFE Tetrafluoroethylene, a high performance thermoplastic polymer that has excellent dielectric strength, chemical and temperature resistance.
Push to Connect Locking arrangement which permits one handed connection by pushing the nipple into the coupler (a.k.a. automatic
R.M.A. Rubber Manufacturers Association.
Ra Log of the arithmetic mean of the surface profile.
Reinforcement The center part of the hose that gives it strength.  The hose working pressure is dependent upon the type (or types) of reinforcement and the amount used in the hose construction.  Types of reinforcement:  Wire Braid, Helical Wire, Textile Braid, Wire Spiral, Textile Spiral                                                             
Reusable Fitting The type of fitting that is designed to be removed from a hose and re-coupled on another hose.
Rotation The act of spinning the coupler and nipple in opposite directions in a continuous manner beyond 360°.
RPM Revolutions per minute
S.A.E. Society of Automotive Engineers
S.A.E. Threads Similar to J.I.C. except 45° conical sealing surfaces.
S.C.F.M. Standard Cubic Feet per Minute.  Typically refers to the amount of compressed air a compressor can produce.
S.M.O.D. Stem Mean Outside Diameter.  The average diameter between the crest of the stem serrations and the root of the stem serrations.
Safety Factor A ratio used to establish the working pressure of a hose based upon the burst pressure.  Typical Safety Factors are as follows:
1.  Water hose up to 150 psi WP:  3 to 1
2.  Hose for all other liquids, solid materials suspended in liquids or air and water hose over 150 psi WP:  4 to 1
3.  Hose for compressed air and other gases:  4 to 1
4.  Hose for liquid media that immediately changes into gas under standard atmospheric conditions:  5 to 1
5.  Steam hose:  10 to 1
Also know as “Design Factor”.
Sanitary (hygienic) Weld Generally considered to be a groove weld in a square butt joint made by the GTAW (or plasma) process as a fusion weld without the addition of filler material.  A sanitary weld must be completely penetrated on the weld ID, with little or no discoloration due to oxidation and be otherwise without defects that would interfere with maintenance in a clean and sterile condition.
Santoprene A thermoplastic elastomer, a rubber-like material that complies with FDA requirements.
Schedule Dimensional standard for pipe as defined by ASTM.
Screw – Together Reusable Fitting A type of hose fitting where the socket and nipple along with the hose are screwed together.
Seal Face Surface point on which a seal is achieved.
Serration The part of the shank (stem) that grips the hose tube.
Serration Crest The top of the serration.
Serration Root The bottom of the serration.
Service Temperature The maximum and minimum temperature of the media.
Service Test Test in which the product is used under actual service conditions.
Set The amount of deformation remaining after the stress has been relieved.
Shank The section of the fitting or coupling that is inserted into the hose.
Shear To break or cut off.
Shelf Storage Life The period of time prior to use during which a product retains its intended performance capability.
Shell Reference Ferrule.
Shut-Off Head The maximum head that a pump can generate.
Silicon Carbide Synthetic mineral of silicon and carbide.  It is used in abrasives, refractories, ceramics and numerous high performance applications.
Silicone Dimethyl silicone, a synthetic rubber.
Single Acting Sleeve Making connection requires manually pulling female sleeve back, inserting the male tip (a.k.a. semi-auto sleeve, manual sleeve)
Sintered Process in which powdered metal is formed in a mold under extreme pressure to form a finished part.
Sintering Heat process in which powdered metal particles are heated to near melting point, fusing the metal granules together.
Skive To remove or cut away part of the hose cover exposing the reinforcement to permit the attachment of a coupling directly over the reinforcement.
Sleeve Lock A coupling arrangement that provides an additional lock which must be actuated before locking sleeve can be retracted (a.k.a. pin-lock, locking sleeve).
Smooth Bore Hose A wire reinforced hose in which the wire is not exposed on the inner surface of the tube.
Smooth Cover A hose cover having an even and uninterrupted surface.
Socket The external member or portion of a hose fitting of a screw – together reusable fitting.
Soft End A hose end in which the reinforcement, usually wire, is omitted.
SPDT Single pole double throw, a type of limit switch.
Specific Gravity A measure of the weight of a liquid in relation to that of water.  If the liquid in question will float on water then the specific gravity will be less than one and if the liquid will sink when mixed with water the specific gravity will be greater than one.
Spike A rapid rise of internal pressure followed by a rapid decrease of internal pressure.
Spillage The fluid released from the system due to disconnection of a quick disconnect coupling. This is the fluid trapped between the mating seal and the valve seal of the coupling halves.
Spring back The attempt of the metal sleeve or ferrule to return to its original diameter.
Spring-Return Any pneumatic actuator which contains a single coil spring or group of coil springs to oppose the Pneumatic Actuator movement of a piston. As air moves the piston or diaphragm, the spring is compressed. When the air supply is discontinued and exhausted, the spring extends and drives the piston in the opposite direction. This type of actuator is normally used for applications where it is necessary for the valve to move to the open or close position upon loss of air supply, whether by design or by system failure.
SPST Single pole single throw, a type of limit switch.
Static Discharge Head The vertical distance in feet between the pump center line and the point of free discharge or the surface of the liquid in the discharge tank.
Static Head The pressure at any point in a liquid can be thought of as being caused by a vertical column of the liquid which, due to its weight, exerts a pressure equal to the pressure at the point in question. The height of this column is called the "static head" and is expressed in terms of feet of liquid.
Static Pressure Pressure that, once released, is not able to be immediately replenished.
Stem Torque The force required at the valve stem to open or close the valve. Torque is expressed in inch pounds or foot pounds.
STP Standard conditions for temperature and pressure. In physical sciences, STP, are standard sets of conditions for experimental measurements, to allow comparisons to be made between different sets of data. National Institute of Standard and Technology's (NIST) version is a temperature of 20°C (293.15 K, 68°F) and an absolute pressure of 101.325 kPa (14.696 PSI, 1 atm).
Suction Head Exists when the source of supply is above the center line of the pump. Thus the static suction head is the vertical distance in feet from the center line of the pump to the free level of the liquid to be pumped.
Suction Lift Exists when the source of supply is below the centerline of the pump. Thus the static suction lift is the vertical distance in feet from the centerline of the pump to the free level of the liquid to be pumped.
Supply Pressure The plant air supply pressure available to operate a pneumatic actuator.
Surface Finish All surfaced as defined by Part SF of the current ASME BPE Standard and/or the owner/user or manufacturer and referred in Ra µin. or µm.
Surge A rapid rise of internal pressure.
Surge (also known as water hammer) A rapid rise or decrease of internal pressure. Surge conditions typically occur, but are not limited to, start and stop sequences.
Surge Flow A rapid increase in fluid flow.
Swage See External Swage.  Often interchanged with the term "crimp".
Swivel The act of spinning the coupler and nipple in opposite directions to a degree that is less than 360°.
System Curve A description of what the pump is required to perform.  The pump will pump where the system curve intersects the pump curve.
System Head The head caused by friction in the piping valves and fittings.
TDH Total dynamic head.  A combination of the suction head and the head being produced by the pump.  Discharge reservoir pressure head + static discharge head + velocity head at pump discharge + total friction head in discharge line.
TEFC Totally Enclosed Fan Cooled motor enclosure.
TENV Totally Enclosed Non Ventilated motor enclosure.
Test Pressure Reference Proof Pressure.
Thermal Build-Up Pressure caused by expansion of a media due to heat from an external source such as sunlight (a.k.a. thermal expansion).
Thixotropic Fluid Viscosity thins with shear.
Torque Amount of force required to turn an object.  Usually measured in inch pounds (in. lbs.) or foot pounds (ft. lbs.)
Torque A twisting or turning force. Usually measured in inch pounds (in. lbs.) or foot pounds (ft. lbs.)
Total Dynamic Discharge Head (hd) The static discharge head plus the velocity head at the pump discharge flange plus the total friction head in the discharge line. The total dynamic discharge head, as determined on pump test, is the reading of a gauge at the discharge flange, converted to feet of liquid and corrected to the pump centerline, plus the velocity head at the point of gauge attachment.
Total Dynamic Suction Head (hs) The static suction head plus the velocity head at the pump suction flange minus the total friction head in the suction line. The total dynamic suction head, as determined on pump test, is the reading of the gauge on the suction flange, converted to feet of liquid and corrected to the pump centerline, plus the velocity head at the point of gauge attachment.
Total Dynamic Suction Lift (hs) The static suction lift minus the velocity head at the pump suction flange plus the total friction head in the suction line. The total dynamic suction lift, as determined on pump tests, is the reading of a gauge on the suction flange, converted to feet of liquid and corrected to the pump centerline, minus the velocity head at the point of gauge attachment.
Total Head (H) or Total Dynamic Head The total dynamic discharge head minus the total dynamic suction head or plus the total dynamic suction lift.

TDH = hd + hs (with suction lift)
TDH = hd - hs (with a suction head)

Total Static Head The vertical distance in feet between the free level of the source of supply and the point of free discharge or the free surface of the discharge liquid.
Trapped Pressure Pressurized fluid trapped behind a closed coupling valve.
Tube The inner most part of the hose that's purpose is to contain the media being transported.  Usually, rubber compounds or plastics are blended to give the tube specific properties so that it is compatible with certain medias.
Tube A hollow cylinder especially one that conveys a fluid. For sanitary applications, a thin wall is implied.
Tube Fitting A length of tubing formed into a usable shape either welded to an apparatus or welded to ferrules for use in an apparatus.
Tubing A piece or length of tube.
Tumble Polish Surface A uniform finish applied by vibratory equipment to stainless steel, varying from matte grey to bright, depending on media used. This process may cause work hardening on the surfaces.
Tungsten Carbide A common hard face seal material available in several grades depending upon hardness and corrosion resistance.  Cobalt and nickel are the two most common binders.
Turbulence Is the condition where the media does not move smoothly parallel to the flow direction. Turbulent flow is caused by abrupt changes in direction, changes of cross-section, or by high velocity. The result is increased friction, which generates heat, decreases operating pressure and wastes power.
Turbulent Flow Irregular flow that is characterized by tiny whirlpool regions. The velocity of this fluid is definitely not constant at every point.
Twist Lock A locking arrangement which requires a rotational actuation to unlock the mating halves.
U.H.M.W. Ultra High Molecular Weight.  Thin tube liner made from extremely dense material having excellent chemical resistance properties.
U.N. Unified National (Constant Pitch) thread
U.N.C. Unified National Coarse thread
U.N.F. Unified National Fine Thread
Vacuum Partially or completely exhausted of air, gas or other media to create a negative pressure. Theoretically, a perfect vacuum would be measured as 30 inches of mercury, but that is unattainable. The true perfect vacuum is 29.7 inches of mercury.
Vapor Pressure Below this pressure the liquid being pumped will vaporize.
Vaporize The fluid passes from a liquid to a gaseous state.
Velocity A measurement of the speed of the liquid in the system; Velocity = distance/time.
Velocity Head (hv) The energy of a liquid as a result of its motion at some velocity V. It is the equivalent head in feet through which the water would have to fall to acquire the same velocity, or in other words, the head necessary to accelerate the water. Velocity head can be calculated from the following formula:
H =  V2 / 2g
where g = 32.2 ft/second-2
V = liquid velocity in feet per second

The velocity head is usually insignificant and can be ignored in most high head systems. However, it can be a large factor and must be considered in low head systems

VFD Variable Frequency Drive. Used to vary the frequency going into a motor, thus varying the speed at which the motor runs.
Victaulic Groove A style of couplings that has a groove cut near the end of the stem where threads would typically be.  The couplings are attached using a "C" shaped clamp that fits into the grooves on the stem.
Viscosity A materials resistance to flow under pressure.
Viscosity Resistance to flow.  Internal friction of a liquid tending to reduce flow.
Volute (casing) Casing surrounding the pump impeller.  The volute converts velocity energy to pressure energy.
W.O.G. Water, Oil, Gas.  Pressure rating for valves handling these products.  This does not include steam.
W.P. Working Pressure
Washdown Duty Motor enclosure that is suitable for a liquid washdown atmosphere.
Water Hammer See surge
Waviness Undulations or rippling of the surfaces.
Welding Join two (or more) pieces of material by applying heat to produce a localized union through fusion across the interface. For sanitary fittings, a ferrule is attached to the ends of a tube fitting by TIG welding without the addition of filler metal. Tube fittings can then be joined with clamps and gaskets to form parts of a system.
WHP Water Horse Power.  The calculated horse power coming out of the pump.
 WHP  =  head x gpm / 3960
WOG Water, Oil, Gas. Pressure rating for valves handling these products. This does not include steam.
Work (Strain, hardening) An increase in hardness and strength caused by plastic deformation at temperatures below the annealing ranges. Work hardening will increase the cost of polishing because of increased hardness and can increase the chance of corrosion in stainless steels.
Working Pressure The maximum pressure to which a hose assembly will be subjected to including pressure surges.
X.L.P.E. Cross-Linked Polyethylene.  Tube material that has good chemical resistance properties.
Zytel® Registered trademark of E.I. duPont Nemours and Company.