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pyranometer
pyranometer Actinometer which measures combined
solar and diffuse sky radiation, sensor viewing entire
visible sky. Also called solarimeter.
Pyrene Trade name for fire exitinguishers and for
carbon tetrachloride filling.
pyrgeometer Actinometer which measures terrestrial
radiation.
pyrheliometer Actinometer which measures only direct
solar radiation.
pyroelectric detector Sensitive detector of IR; radiation
enters via precision window of Ge and light pipe directs it
to microscopic flake of TGS which rises in temperature,
changing polarization and generating surface charge
amplified in low-noise electronics.
pyrogen Pyrotechnic generator; ignition squib for solidpropellant
motors comprising electric resistance or
bridgewire which ignites hotburning powder charge.
pyroharness Network joining pyrometers, usually round
an engine.
pyrolitic carbon Allotrope of carbon derived from
controlled pyrolysis of char-yielding resin (eg phenolic
resoles or Novolaks) to form matrix used in
carbon/carbon composite, with reinforcement by carbon
PZT
or graphite fibre. Used in rocket nozzle liners, hightemperature
wheel brakes, etc.
pyrolysis Chemical decomposition by heating.
pyromechanical actuator One energized by solid fuel or
other combustible charge.
pyrometer Instrument for measuring high temperatures;
optical, electrical resistance, thermocouple, radiation, etc.
pyron Non-SI unit of EM radiant intensity (no abb.), =
calories (Int.)/cm 2 /min.
pyrophoric Igniting spontaneously on contact with air.
pyrotechnic Today includes not only visual ‘firework’
devices but also precision igniters for large solid motors,
single-shot actuators, hot-gas generators and IR flares
giving accurately controlled decoy wavelength.
Python Becoming important as a computer language for
engineering and science.
pz See pièze.
PZD Petrolatum/zinc dust.
p o , p zero Free-stream static pressure.
PZRK Portable rocket (missile) air-defence system (R).
PZT 1 Lead zirconate titanate.
2 Piezoelectric translator.
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