Terminology/Glossary

TERMS USED IN THE INDUSTRY

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.

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.

ANSI
American National Standards Institute, Inc.

ASME
American Society of Mechanical Engineers

ASTM
American Society for Testing and Materials

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.

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.

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.

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.

Buna
Synthetic rubber, a copolymer of acrylonitrile and butadiene.

Burst Pressure
The pressure at which rupture occurs.

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

Clamp
A device used to join mechanical parts, fittings, ensuring a quick leak-proof connection and enabling easy take down.

Cold Flow
Continued deformation or movement of rubber or PTFE under stress.

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.

CW
Clockwise

DA
Double acting

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.

DPDT
Double pole-double throw

Durometer
An instrument for measuring the hardness of rubber.

Durometer Hardness
A numerical value, which indicates the resistance to indentation of the blunt indentor of the durometer.

EPDM
Ethylene propylene diene monomer, a synthetic rubber.

Elastomer
Any of various elastic substances resembling rubber.

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.

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.

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 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
A small part of an apparatus (may be detachable).

Fluorocarbon
Elastomer known as Viton® a registered trademark of DuPont.

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.

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.

Hex Union Nut
An internally acme-threaded six-sided connector used to assemble bevel seat fittings.

ISO5211
International standard for valve and actuator interface.

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.

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.

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.

Maximum-Shut-Off
The pressure of the media flowing into the valve against which the valve will have to close.

Media
The material flowing through the system.

MTR
Material Test Report

Modulating Service
Proportional positioning of a valve between the open and closed positions, used for flow control processes.

NAMUR
International Standard of Interface for Actuator Accessory Connections.

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.

Nominal Size
A dimensional value assigned for the purpose of convenient designation, used for pipes.

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.

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.

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.

Polypropylene
A lightweight synthetic plastic.

Pressure
The force per unit area applied on a surface in a direction perpendicular to that surface.

PSI
Pounds per square inch

PSIG
Pounds per square inch gauge

PTFE
Tetrafluoroethylene, DuPont's Teflon®, a high performance thermoplastic polymer that has excellent dielectric strength, chemical and temperature resistance.

Santoprene
A thermoplastic elastomer, a rubber-like material that complies with FDA requirements.

Silicone
Dimethyl silicone, a synthetic rubber.

Sintering
Heat process in which powdered metal particles are heated to near melting point, fusing the metal granules together.

SPDT
Single pole-double throw

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

Stem Torque
The force required at the valve stem to open or close the valve. Torque is expressed in inch pounds or foot pounds.

Supply Pressure
The plant air supply pressure available to operate a pneumatic actuator.

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.

Torque
A twisting or turning force. Usually measured in inch pounds (in. lbs.) or foot pounds (ft. lbs.)

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.

Turbulent Flow
Irregular flow that is characterized by tiny whirlpool regions. The velocity of this fluid is definitely not constant at every point.

WOG
Water, Oil, Gas. Pressure rating for valves handling these products. This does not include steam.

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.

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.