The fundamental temperature scale with its zero at absolute zero and expressed in degrees Kelvin. One degree Kelvin is equal to one degree Celsius or one degree Centigrade. For the purpose of practical calculations in order to convert Celsius to Kelvin add 273. It is normal for the degree Kelvin to be abbreviated in mathematical formulae to ‘K’ with the degree symbol being omitted.
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FLASH POINTThe lowest temperature at which a liquid gives off sufficient vapor to form a flammable mixture with air near the surface of the liquid. The flashpoint temperature is determined by laboratory testing in a prescribed apparatus. Establishes the danger point when transferring, pumping, and firing procedures are concerned. |
POLYFORMING
A noncatalytic, petroleum-refinery process charging C3 and C4 gases with naphtha or gas oil at high temperature to produce high-quality gasoline and fuel oil; mostly replaced by catalytic reforming; the prodTesting and Materials analysis of paraffins (P), olefins (O), naphthenes (N), and aromatics (A) in gasolines.
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POLARIZING PYROMETER
A type of pyrometer, such as the Wanner optical pyrometer, in which monochromatic light from the source under investigation and light from a lamp with filament maintained at a constant but unknown temperature are both polarized and their intensities compared.
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PLAIN CONCRETE
Concrete without reinforcement but often with light steel to reduce shrinkage and temperature cracking.
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PILOT WIRE REGULATOR
Automatic device for controlling adjustable gains or losses associated with transmission circuits to compensate for transmission changes caused by temperature variations, the control usually depending upon the resistance of a conductor or pilot wire having substantially the same temperature conditions as the conductors of the circuits being regulated.
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PH METER
An electronic voltmeter using a pH-responsive electrode that gives a direct conversion of voltage differences to differences of pH at the temperature of the measurement.
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PERIODIC KILN
A kiln in which the cycle of setting ware in the kiln, heating up, soaking'' or holding at peak temperature for some time, cooling, and removing or drawing'' the ware is repeated for each batch.
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PERMANENT GAS
A gas at a pressure and temperature far from its liquid state.
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ORDER OF PHASE TRANSITION
A phase transition in which there is a latent heat and an abrupt change in properties, such as in density, is a first-order transition; if there is not such a change, the order of the transition is one greater than the lowest derivative of such properties with respect to temperature which has a discontinuity.
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OPTICAL PYROMETER
An instrument which 382 determines the temperature of a very hot surface from its incandescent brightness; the image of the surface is focused in the plane of an electrically heated wire, and current through the wire is adjusted until the wire blends into the image of the surface. Also known as disappearing filament pyrometer.
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