Equipment II Glossary accumulator A device used to reduces fluid pressure pulsation by trapping the fluid and returning it to the system using a piston system, diaphragm, or other mechanism. air infiltration (vapor lock) A condition where air is pulled into a pumping system or air is trapped in a section of the process line. axial fan A type of fan in which gas is moved forward in a straight line along the axis. axial pump A type of pump in which liquid is moved forward in a straight line along the axis. barometric leg A length of pipe that drains condensate from condensers or other equipment in a vacuum system. belt drive A drive component that uses a pulley and belt system to create rotation and torque from a driving shaft to a driven shaft. blower A compressor that moves high volumes of air at low differential pressures. brake horsepower The horsepower required at the pump shaft to pump a liquid at the specified head and flow. cavitation A phenomenon that can occur in a liquid, where vapor bubbles form and then implode due to pressure changes within the liquid. centrifugal fan A fan that uses centrifugal force to accelerate a gas and increase pressure. centrifugal pump A type of dynamic pump that uses centrifugal force to accelerate a fluid and increase pressure. chain drive A drive component that uses a pulley and belt system to create rotation and torque from a driving shaft to a driven shaft. circulating oil system A system that delivers cooled oil continuously to high speed equipment and other applications. clutch Mechanical switch positioned between a motor and a driven shaft on a piece of equipment. compressor A mechanical device that increases the pressure of a gas by forcing it into a smaller volume. coupling A mechanical device used to directly connect two shafts into one long continuous unit. diffuser Stationary impeller-like disks that may be located in a centrifugal pump cavity to reduce turbulence and improve efficiency by directing the fluid in a more controlled manner into the volute and to the discharge port. dynamic compressor A category of compressors that accelerate the flow of the gaseous fluid then convert the additional energy generated to pressure. dynamic pump A type of pump that has an impeller which spins around the pump’s axis to move the fluid through the pump. foot valve A device designed to prevent liquid from draining out of the suction line when the pump is shut down. gear drive A drive component that uses gears to create rotation and torque from a driving shaft to a driven shaft. grease gun A device that delivers grease to a lubrication application. impeller A rotating device in a pump used to increase pressure and flow of a fluid. induction motor A type of AC motor in which current is induced from the rotating magnetic field established when the stator is powered. knockout pot A device used to prevent liquids containing solids from entering a pump. mixed flow fan A fan in which air is drawn through an inlet like a centrifugal fan but exits in a flow path similar to an axial fan. mixed flow pump A type of pump with the characteristics of both an axial pump and a centrifugal pump. motor A machine that converts electrical energy into mechanical energy. motor control center (MMC) A cabinet or closet that houses motor controllers, power switches, ground-fault protection, fuses, and contactors. motor controller Device use to control the operation of a motor including rotation direction, speed, torque, and overloads. Net Positive Suction Head Available (NPSHA) The total energy available at the discharge of a pump taking into account energy losses in suction piping and increases due to pressure of the fluid and for any suction lift. Net Positive Suction Head Required (NPSHR) The energy required by a pump at a given operating point to prevent cavitation. positive displacement compressor A category of compressors that displace gas in a chamber and then compress the gas by reducing the volume of the chamber. positive displacement pump A pump that moves a fixed volume of fluid during each cycle. pump A mechanical device that transfers energy to a fluid. pump efficiency The percent of energy that the pump imparts to the liquid divided by the energy the pump requires to do the work. reciprocating compressor A category of positive displacement compressors that use a piston to drive a gas into a smaller space. rotary compressor A category of positive displacement compressors that use a rotor to compress a fixed volume of gas during each rotation. rotor (armature) The rotating component in a motor. slip The difference between the ideal and actual rotational speed of a piece of equipment. stall A condition in which inlet air hits the fan blades at an angle resulting in non-uniform pressure. stator The stationary component in a motor or other rotary system in or around which the rotor turns. strainer Device used to removed solid contaminates from a liquid stream. stuffing box The area around the pump shaft that holds packing in place. surge In a compressor or fan, a reduction of flow to one or more of the impellers or stages that causes large differences in discharge pressure. synchronous motor A type of AC motor in which power is supplied directly to the rotor which in turn creates a magnetic field around the rotor. vacuum A gas in a closed container that is below the surrounding atmospheric pressure. vacuum break Any device or configuration that prevents backflow of air or liquids if vacuum production is interrupted vacuum system A vacuum source and the piping and fittings that move gases from a process through the vacuum source to a point where it is vented to the atmosphere. variable pitch controller Electric or pneumatic control devices that control fan airflow volume by blade pitch. viscosity A fluid's resistance to flow. windings Groups of coiled insulated wires located in a motor stator that fo