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A wave generated by friction between wind and a fluid surface. Ocean waves are produced principally in this way.
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Related Terms |
PNEUMATIC CONTROL VALVE
A valve in which the force of compressed air against a diaphragm is opposed by the force of a spring to control the area of the opening for a fluid stream.
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PNEUMATIC DRILLING
Drilling a hole when using air or gas in lieu of conventional drilling fluid as the circulating medium; an adaptation of rotary drilling.
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PLUMMET
A loose-fitting metal plug in a tapered rotameter tube which moves upward (or downward) with an increase (or decrease) in fluid flow rate upward through the tube. Also known as float.
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PLUG VALVE
A valve fitted with a plug that has a hole through which fluid flows and that is rotatable through 90 for operation in the open or closed position. Also known as plug cock.
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PLUG METER
A variable-area flowmeter in which a tapered plug, located in an orifice and raised until the resulting opening is sufficient to handle the fluid flow, is used to measure the flow rate.
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PITOT TUBE
An instrument that measures the stagnation pressure of a flowing fluid, consisting of an open tube pointing into the fluid and connected to a pressure-indicating device. Also known as impact tube.
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PISTON PUMP
A pump in which motion and pressure are applied to the fluid by a reciprocating piston in a cylinder. Also known as reciprocating pump.
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PIEZOMETER
1. An instrument for measuring fluid pressure, such as a gage attached to a pipe containing a gas or liquid. 2. An instrument for measuring the compressibility of materials, such as a vessel that determines the change in volume of a substance in response to hydrostatic pressure.
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PERMEATE
The clear fluid that passes through the membrane in a membrane filtration process.
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PECLET NUMBER
Dimensionless group used to determine the chemical reaction similitude for the scale-up from pilot-plant data to commercial-sized units; incorporates heat capacity, density, fluid velocity, and other pertinent physical parameters.
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