Glossary of Compressed Air Terms :: M :: Glossary Index A B C D E F G H I J K L M N O P Q R S T U V W X Y Z M3/min M3/hr Volume flow rate measured in cubic meters per minute (or per hour) Mach number is the ratio of the actual velocity at a given point to the velocity of sound in the same gas at the conditions existing at this point. These are known as local conditions. Man way An inspection cover or port in an air receiver tank. MAWP Maximum allowable working pressure. This data is found on the pressure vessel nameplate and is the maximum pressure at which the lowest set safety valve must be set (stamped). Maximum operating pressure The highest operating pressure the system or component is designed to withstand. Mayonnaise The oily condensate discharged by lubricated air compressors. The name is derived from the appearance of the condensate. Under normal conditions oily condensate should just be cloudy, like a small amount of milk in a bucket of water. When a lubricated compressor goes wrong, then the condensate becomes thick and sticky. In fact almost identical in appearance to the name it has been given. Mechanical efficiency The ratio of the indicated power to shaft input. Media A mat of fibers that provide a barrier to particles entrained in the flow of air or gas. Media migration Carry over of particles or contaminant from the filter or other filter materials into the clean side of the air flow. Medium Is singular for media and is the material...paper, wire, cellulose or a combination... from which the filter element is made and which does the actual filtration or separation. Membrane dryer Reduce dew point by passing compressed air through a bundle of hollow membrane fibers; water vapor and a portion of the compressed air then permeate the membrane walls and vent to atmosphere Mesh size Mesh is the number of openings in a square inch of screen or sieve. It is equal to the square of the number of strands of metal or plastic screening per lineal inch. Standard US mesh screen # 16 equates to a 1.19 millimeter particle diameter, mesh size #40 is 0.42 millimeters. Micron Micrometer or one millionth of a meter; micron is sometimes represented in filtration by the Greek letter µ (mu). A micron is 0.000039". Contaminant particles are measured by micron size and count. Micron rating A measurement applied to filters or filter media to indicate the particle size at which suspended solids above that size will be removed. Millibar A unit of atmospheric pressure equal to 1,000 dynes per sq. cm. or about 1/32 in. of mercury. Mineral oil The most commonly used lubricating oil for compressors. MMCFD Millions of cubic feet per 24 hour. Modulating control Compressor controls will run the compressor at varying loads to accommodate demand variations. Running a compressor at less than full load results in a drop in compressor efficiency and thus an increase in operating costs. Modulating unload The air compressor continues to run and air supply is matched to the demand by partial unloading. This can be accomplished by a regulator controlled floating inlet or by step unloading. Moisture separator A unit designed to separate condensate from the compressed air stream. Moisture trap A device designed to enable accumulated liquids to be held for draining in a compressed air system. Molecular sieves A solid adsorbent used for drying compressed air. Molecular theory All matter consists of molecules which are in constant motion, but which are held together by molecular forces. In a solid the molecules are closely packed and arranged in such a pattern that the influence of the molecular forces is very strong. This gives the solid its consistency and form. Molecular motion consists largely of oscillations around points of equilibrium. In a liquid the molecules are about as close as in a solid, but they are not arranged in a lattice and the cohesive forces are weaker. The molecules are more mobile in relation to each other, whereby the characteristic liquid phase develops; the liquid accommodated itself to the walls of the containing vessel, and its free surface aligns itself horizontally in response to the force of gravity. In a gas, however, the molecules are farther apart, and they move freely about each other since the molecular forces are not as strong. A gas therefore expands through space and mixes with other gasses present. The total volume of the molecules in a gas is very small in relation to the volume of the gas. A gas can therefore be compressed into a small part of its original volume. Mottling In spray painting applications, blotches of metallic or mica particles in a paint film caused by insufficient compressed air MPCV Combination minimum pressure valve and check valve. MSDS ACRONYM - MATERIAL SAFETY DATA SHEETS Multistage axial compressor A machine having two or more impellers operating in series on a single shaft and in single casing. Multistage centrifugal compressor A machine having two or more impellers operating in series on a single shaft and in single casing. Multistage compressor A machine employing two or more stages. Glossary Index A B C D E F G H I J K L M N O P Q R S T U V W X Y Z