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| A |
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Angstrom, a unit of measure equal to 1 X 10-10 meters in length.
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| AA |
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Abbreviation commonly used for atomic absorption spectroscopy.
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| ASTM |
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American Society of Testing Materials, an organization which sponsors committees which develop standards for Industrial Manufacturers and Consumers.
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| Absolute Pressure |
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A measurement of pressure which sets a total vacuum as having a value of zero. For example the commonly used term psia stands for pounds per square inch of absolute pressure.
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| Absolute Zero |
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The lowest point in the Kelvin temperature scale. 0°K = - 459.67°F or -273.15°C in the Farenheit or Celsius temperature scales, respectively.
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| Absorption |
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The physical penetration of a substance into the structure of another substance, such as the dissolution of a gas into a liquid.
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| Accuracy Expresses |
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the degree of agreement of a measured value when compared to the true or expected value of the quantity of concern. This term is often confused with precision, which is the range of the confidence level within which a measured value can be considered valid.
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| Adsorption |
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The adherence of molecules, ions or atoms of a gas or liquid to the surface of another substance. The adsorbed species is thought to be adhered to the surface by weak physical or chemical forces.
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| Aerobic |
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Describes gases that contain oxygen and which are commonly used as atmospheres for biological culture growth.
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| Anaerobic |
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Describes gases that do not contain oxygen which are used for biological culture growth.
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| Anhydrous |
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Literally means without water. The term is often used with those gases that are particularly corrosive in the presence of moisture, such as ammonia.
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| Annealing Gas |
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A gas blend used as a reducing atmosphere in the metals industry during heating to render them less brittle. A commonly used furnace gas consists of a blend of hydrogen and nitrogen.
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| Asphyxiant Gas |
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A gas which displaces air in an enclosed space and which can cause
unconsciousness or death due to lack of oxygen.
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| Azeotrope |
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A mixture of two substances that typically cannot be separated easily by simple distillation. A commonly used term to describe a liquid mixture that has a constant boiling point.
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| Bar |
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One Bar equals 10^5 Newtons per square meter (=14.5 psi or 1.02 kg/cm^2)
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| BTU |
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An abbreviation for British Thermal Unit, a unit of energy defined as the quantity of heat needed to raise the temperature of one pound of water 1°F.
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| Boiling Point (BP) |
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The temperature of a liquid at which the vapor pressure is equal to the pressure of the atmosphere above it.
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| Bourdon Tube |
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A curved metal tube commonly used in pressure gauges. The tube flexes a known degree as pressure is applied, and that movement is translated as the physical movement of a gauge needle across a scale.
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| Boyle’s Law |
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A gas law which states that for an Ideal Gas at constant temperature the volume of the gas is inversely proportional to the pressure applied.
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| Burst Pressure |
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The designed test pressure at which a gas-containment device such as a cylinder, piping or pressure adjusting device will begin leaking but not violently rupture. For most gas handling equipment, the industrial standard is that the burst pressure is four times (400%) of the normal operating pressure.
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