AWESCO - Glossary: A

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Absolute Pressure – A quantity of pressure measured with respect to total vacuum. Equal to the sum of a pressure gauge reading and atmospheric pressure.

Absolute Zero – The minimum point in thermodynamic temperature scale (-273.1 6 ?C or -459.69 F)

Absorption – The penetration of matter in bulk into other matter, as in the dissolving of a gas in liquid.

AC - Alternating Current. Produced by all transformer type welding machines.

Accuracy – The degree of agreement of a measured value with the true or expected

value of the quantity of concern.

Adsorption – Adherence of the atoms, ions or molecules of a gas or liquid to the surface of another substance, called the adsorbent. Molecular Sieves are adsorbents.

Advanced Squarewave - The advanced AC output available from certain types of power sources. The wave is much more square than the conventional Squarewave power source. It also has expanded balance control to 90% electrode negative (max penetration) and the ability to control arc frequency (arc direction). Some have the additional ability to adjust the amount of current in the electrode negative and electrode positive cycles independently.

Air Carbon Arc Cutting - A cutting process by which metals are melted by the heat of an arc using a carbon electrode. Molten metal is forced away from the cut by a blast of forced air.

Alternating Current (AC) - An electrical current that reverses its direction at regular intervals, such as 60 cycles alternating current (AC), or 60 hertz (Hz).

American Conference of Governmental Industrial Hygienists (ACGIH) – This Conference is a professional society, not an official Government Agency. It is an organization devoted to the development of administrative and technical aspects of worker protection.

Amperage - The measurement of the amount of electricity flowing past a given point in a conductor per second. Current is another name for amperage.

Anhydrous – Descriptive of an inorganic compound that does not contain water.

Anneal - To soften by heating and cooling. To anneal carbon steels, low alloy steels and martensitic stainless steels, the steels are heated to a temperature greater than the critical temperature range and cooled slowly, usually by a controlled cooling rate in the furnace. To anneal austenitic stainless and manganese steel, the steel is heated to at least 1850°F and cooled rapidly, usually by quenching in water.

Annealing - The opposite of hardening. A heat treating process used to soften a metal and relieve internal stresses.

Anodize - To anodize aluminum is to coat the metal by either chemical or electrical means. The coating provides improved corrosion and wear resistance. The thickness of this coating depends upon the length of the treatment. This coating is often removed from the area to be welded. This coating can be reapplied after welding.

Arc - The physical gap between the end of the electrode and the base metal. The physical gap causes heat due to resistance of current flow and arc rays.

Arc Length - Distance or air space between the tip of the electrode and the work.

Arc Voltage - Measured across the welding arc between the electrode tip and the surface of the weld pool.

Asymmetric Waveform - The output waveform of a welding power source that has the ability to modify both the amplitude and duration of the positive and negative half cycles of alternating current.

Asphyxiant Gas – A gas which has little or no positive toxic effect but which can bring about unconsciousness and death by replacing air and thus depriving an organism of oxygen.

Attached Poppet (Tied-Seat; Tied-Diaphragm) – A feature of certain regulators whereby the stem (poppet) is physically attached to the diaphragm.

Atomic Weight – The relative weight of an atom of an element, compared to carbon-12. Equivalent to the sum of protons and neutrons in the nucleus.

Autogenous Weld - When a TIG weld is made without the addition of filler metal.

Automatic Welding (AU) - Uses equipment which welds without the constant adjusting of controls by the welder or operator. Equipment controls joint alignment by using an automatic sensing device.

Axis of Weld - Can be thought of as an imaginary line through the center of a weld, lengthwise.

Azeotropic Mixture (Azeotrope) – A liquid mixture of two or more substances which behaves like a single substance in that the vapor produced by partial evaporation of liquid has the same composition as the liquid. The constant boiling mixture exhibits either a maximum or minimum boiling point as compared with that of other mixtures of the same substances.

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