Panasonic PT-DZ12000U Operating Instructions Manual page 141

Power - The units of power are horsepower (hp) and watts
(w) or kilowatts (kw). One U.S. horsepower equals 0.746 kw
and 1.014 metric horsepower.
Absolute Pressure - In pressure or vacuum systems,
absolute pressure is the pressure above a perfect vacuum
condition (zero pressure). In a pressure system, it is equal to
the positive gauge pressure plus atmospheric pressure. In a
vacuum system, it is equal to the negative gauge pressure
subtracted from atmospheric pressure. U.S. units for absolute
pressure are pounds per square inch, absolute (psia).
Adiabatic - A change, such as expansion or compression,
without loss or gain of heat. Any sufficiently fast process is
approximately adiabatic.
Atmosphere - Unit of pressure that will support a column of
mercury 29.92 inches high at 0 C, sea-level, and latitude 45.
Actual day-to-day atmospheric pressure fluctuates about this
value.
Atmospheric Pressure - Pressure exerted by the
atmosphere in all directions, equal at sea level to about 14.7
psi.
Back Pressure - Resistance to flow in a system.
Barometer - Device for measuring atmospheric pressure at a
specific location.
Barometric Pressure - The reading, in inches of mercury
("Hg), showing atmospheric pressure at a given location.