Some of the terms that are commonly used while describing industrial fittings

Alloy Steel
A steel which owes its characteristic properties to elements except carbon.

Area of a Circle
It is the measurement of the surface within a circle. To locate the area of a circle, multiply the product of the radius times the radius times Pi (3.142).

Adapter
A type of fitting providing a method of joining two components of differing thread types or systems.

Analytical Column
A long narrow tube filled with chemically diverse compounds that can separate the components in a sample according to their boiling point, polarity, molecular size, or other combinations. A column of some kind is used with most chromatographic techniques.

Air Inclusion
The ambient atmosphere forced or trapped into the system during connection of the quick-action coupling halves

Backflush
The use of valving to reverse the flow through a column in order to "backflush" or purge heavier components from the column.

Biocompatibility
Includes those materials used in a system (i.e. fittings, tubing, and valves) that does not alter the bioactivity of the biological substances that come into contact with the surface materials.

Bore
It is the diameter of the minimum orifice through the fitting.

Bulkhead Fitting
A type of fitting in which the fitting body is inserted through an instrument panel or mounting bracket, to which it is affixed with a mounting nut. The Valco fitting body is uniquely undercut so that it "bites" into the panel when the mounting nut is tightened, eliminating the need for a lock washer.

Butt Connection
A type of connection in which the two tube ends are directly and squarely in contact, usually effected with a through-type union. Typically used with fused silica connections, or small bore metal tubing.

Braze Weld or Brazing
A process of joining metals using a nonferrous filler metal or alloy, the melting point of which is higher than 800 degrees F(427 degrees C) but lower than that of the metals to be joined.

Butt Weld
A circumferential weld in pipe fusing the abutting pipe walls completely from inside wall to outside wall.

Cap
A cap is used to dead-end a piece of tubing using a nut and ferrule.

Capillary bore
The smallest available standard orifice in a given fitting design (usually 0.25 mm). Typically denoted by suffix "C" in the product number.

Compression Fitting
A style of fitting in which a threaded nut compresses a tapered ferrule onto tubing as the nut is tightened. Valco metal ferrules cut a ring into the tubing wall while polymer types rely on surface compression to form a seal.

Connecting Volume
The volume between two or more connections. This may be cleanly swept and so does not contribute to peak distortion, or may be "dead volume" such as that found in fittings with larger bores than the connecting tubing.

Cross
A type of distribution fitting which connects four pieces of tubing, giving it the shape of a cross.

Carbon Steel
A steel which owes its distinctive properties, mainly to various percentages of carbon (as distinguished from the other elements) which it contains.

Circumference of a Circle
The measurement around the perimeter of a circle. To find the circumference, multiply Pi (3.142) by the diameter.

Coefficient of Expansion
A number that indicates the degree of expansion or contraction of a substance. The coefficient of expansion is not constant and keeps varying with changes in temperature. For linear expansion it is expressed as the change in length of one unit of length of a substance having one degree rise in temperature.

Corrosion
The gradual destruction or changes of a metal or alloy caused by direct chemical attack or by electromechanical reaction.

Creep
It is the plastic flow of pipe within a system; the permanent set in metal caused by stresses at high temperatures. Generally associated with a time rate of deformation.

Distribution Fitting
A general term for 'tees', crosses', and 'manifolds', used to provide multiple access points to "distribute" a gas or liquid through a system. Using a distribution fitting in reverse to combined multiple streams may create dead volume so special manifolds are available for this application.

Diameter of a Circle
It connotes a straight line, drawn through the center of a circle from one extreme edge to the other which equals twice the radius.

Ductility
The property of elongation, above the elastic limit, but under the tensile strength is ductility. A measure of ductility is the percentage of elongation of the fractured piece over its original length.

Elastic Limit
The highest stress a material can withstand without a permanent deformation after release of the stress.

Erosion
The gradual destruction of metal or other material by the abrasive action of liquids, gases, solids or blend of substances.

Emitter
It is a tube receiving water from a collector or interceptor. Emitters do not receive any additional runoff in their path, and their function is to carry waste waters to the treatment plant. The tube carrying treated water from the treatment plant to the discharge site is also known as emitter.

Female Nut
A type of compression fitting in which the nut has female threads.

FIA
Flow Injection Analysis. A simple and versatile analytical technique for automating wet chemical analyses based on the manipulation of a sample zone formed from the injection of the sample into a continuous stream of fluid used as a carrier.

Ferrule
It is the conical piece of metal or plastic that compresses onto the tube as it is forced into a tapered seat. Valco metal ferrules are unique because they get sealed and attached to the tube by cutting a shallow ring into it. This is preferable since it introduces no flow restriction.

Filter
A type of union or reducing union which traps substances in a stream where the filtering element is a mesh screen.

Fitting Detail
One of the components of a compression fitting; if the tube, nut, and ferrule comprise the male part of the fitting, the fitting detail is the female part. It includes the threads for the nut, the tapered ferrule seat, and the pilot.

Flanged Nut
A type of nut used with fluoropolymer tubing in which a flange is made at the tube end. Connections are made at the flange either by compressing the flange into a flat detail (typically 1/4"-28 threaded) or by butting two flanges together. A special flanging tool forms the flanges.

Flangeless Nut
Similar in application to the flanged nut, but the flange is not required. A ferrule system is used which grips/compresses the tube. This fitting type can be used with virtually any polymeric tubing since the tube end does not have to be formed, but simply square cut. Typically used in 1/4"-28 threaded fitting details, it is usually interchangeable with flanged nut.

Frit
A filter element made of stainless, Hastelloy, Titanium, or polymers, usually 0.75 mm or 1 mm thick. Frits may provide better filtration than screens, but since they are thicker there is greater mixing potential, and so result in increased pressure drop.

Flexible system
Property of a sanitary piping line to enable a relative movement between components (tube, fittings and accessories).

GC
Gas Chromatography, an analytical method incorporating an injection system, analytical column, controlled temperature zone, and detector. An inert carrier gas moves the sample through the column, which separates the sample components into discrete bands which are measured as they pass through the detector.

Guard column
A column used in series between the injector and analytical column to prevent certain types of components from entering the analytical column.

HPLC
High Performance Liquid Chromatography. An analytical system consisting of an injector, pump, analytical column, and detector. Using a liquid mobile phase, the sample is pumped through the column, where it is separated into discrete sample component bands which are detected and measured as the bands elute from the column.

ID
Internal diameter.

Inert
Technically its means 'unreactive' with other substances but in the instrumentation field, it's a relative term. Often polymers are termed inert but are soluble in some fluids and can react with some compounds.

LC
Liquid Chromatography. Any of a variety of low to medium pressure techniques which use a liquid mobile phase as the carrier to move sample, similar to HPLC.

Large Bore
A bore that is larger than the standard for a given fitting; a fitting ordered with a large bore will have a larger flow orifice than the standard or capillary bore fitting of the same design. Denoted by suffix "L" in the product number.

Luer Adapter
It is an adapter connecting a tapered luer fitting (square nib) of a syringe to a tube or tube fitting.

Male Nut
A type of compression fitting in which the nut has male threads.

Make up
The point at which a ferrule, nut, and tube are assembled in the fashion which will effect a leak-free seal. In most compression fittings, that is accomplished by compressing the tube with the small end of the ferrule. With Valco metal ferrules, the ferrule usually makes up on the tube by cutting a shallow ring in it.

Manifold
A type of distribution fitting in which a single source is directed to multiple outlets, or vice versa. Using a common distribution fitting in reverse to merge multiple streams may create dead volume. Special manifolds are available for this application.

Microbore Column
A liquid chromatography column of narrow bore (typically 2 mm or less) for improved resolution.

NPT
National Pipe Thread; a standardized tapered pipe fitting.

Nut
It is the tensioning element of a compression fitting. As the threaded nut is tightened into the fitting detail, it pushes the ferrule forward into the tapered ferrule seat, causing it to make up on the tube.

Pilot
The tubing which extends beyond the ferrule in a made-up fitting, or the integral portion of a ZRF internal reducing ferrule which extends beyond the ferrule.

Pilot depth
The length of the tubing diameter cavity beyond the tapered ferrule seat within a fitting detail. Valco fitting pilot depths are tightly controlled to facilitate the interchange ability of components without the risk of leaks or dead volume.

Pipe thread
The external or internal threads of a fitting designed to effect a metal-to-metal seal on the conical thread faces. This type of fitting does not "bottom out" in the detail. Typically used with Teflon tape or other compounds to lubricate the threads. But since the diffusion rate of air components through the Teflon tape is considerable, pipe fittings should not be used in systems where leakage rates are critical.

Port
The connection, orifice, seal, or septum, etc. through which samples may be added (injected) or withdrawn.

Reducing ferrule
A ferrule which allows a smaller tube to be used in a fitting detail designed for a larger tube. It should be taken if standard reducing ferrules (RF) without integral pilots are used, since dead volume may be created in the fitting pilot depth.

Reducing union
A fitting which joins two tubes of different ODs. The bore of the fitting should match the ID of the smaller tube.

Radius of a Circle
A straight line drawn from the center to the extreme edge of a circle.

Socket Fitting
A fitting used to join pipe in which the pipe is inserted into the fitting. A fillet weld is then made around the edge of the fitting and outside the pipe.

Soldering
A method of joining metals using fusable alloys, usually tin and lead, having melting points under 700 degrees F(371 degrees C).

Strain
Change of shape or size of a body produced by the action of a stress.

Stress
It is the intensity of the internal, distributed forces which resist a change in the form of a body. When external forces act on a body they are resisted by reactions within the body which are termed stresses.

Stress, Compressive
It is the stress that resists a force to crush a body.

Stress, Shearing
It is the stress that resists a force to make one layer of a body slide across another layer.

Stress, Tensile
It is the stress that resists a force to pull a body apart.

Stress, Torsional
It is the stress that resists a force to twist a body.

Tensile Strength
The maximum tensile stress which a material will develop. The tensile strength is usually thought over as the load in pounds per square inch at which a test specimen disrupts.

Turbulence
Any deviation from parallel flow in a pipe due to rough inner walls, obstructions or directional changes.

Tee
A type of distribution fitting connecting three pieces of tubing, arranging them in the shape of a "T".

Through-type bore
A bore, used with the given fitting, and which is slightly larger than the OD of the tubing. A union with a through-type bore allows the tube ends to butt directly together, or for one tube to run completely through the fitting. It is denoted by suffix "T" in the product number. In order to ensure correct pilot lengths, ferrules should be made up on the tubing in a standard union.

Union
A fitting for connecting two pieces of tubing of the same OD, or different OD's.

Female union: a type of compression fitting in which the fitting body has female threads. Also referred to as an internal union.
Male union: a type of compression fitting in which the fitting body has male threads. Also referred to as an external union.

Unswept volume
The volume of any portion of a fitting which is in the flowpath but which is a different diameter than the primary flow orifice through the tubing/fitting assembly, or any area not directly swept by the fluid flow. It is also known as "dead volume" if inadequately swept

Velocity
Time rate of motion in a given direction and sense, usually expressed in feet per second.

Volume of a Pipe
The measurement of the space within the walls of the pipe. To find the volume of a pipe, multiply the length (or height) of the pipe by the product of the inside radius times the inside radius times Pi (3.142).

Welding
A process of joining metals by heating until they are fused together, or by heating and applying pressure until there is a plastic joining action. Filler metal may or may not be used.

Wetted surfaces
The surfaces which are contacted by the sample stream.

Y
A type of distribution fitting connecting three pieces of tubing, arranging them in the pattern of a "Y". Occasionally referred to as a "wye".

Yield Strength
It's the stress at which a material manifests a specified inciting permanent set.

ZDV
Abbreviation for zero dead volume.

Zero dead volume (ZDV)
It is a connection which does not add volume to the system beyond which an extension of tubing would if in its place.

Zero volume
Often used interchangeably with ZDV, it means a fitting design in which there is no internal volume, such as a through-type union designed to butt-fit two pieces of tubing.