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Section 17 Glossary
17.1 Gas units
17.2 Generic terms and definitions
Unit Meaning
% air
percentage, by weight. A concentration of 100% air corresponds to liquid saturated with air at current
pressure and temperature. The equivalent concentration of O
2
is approximately 20% O
2
in normal
conditions.
% O
2
percentage, by weight. A concentration of 100% O
2
corresponds to liquid saturated with pure O
2
at
current pressure and temperature.
%Vbar ratio in percent between the partial pressure of gas measured and the atmospheric pressure
%Vext
ratio in percent between the partial pressure of gas measured and the external pressure. Available when
an external pressure sensor is present.
µg/L micrograms per liter
atm atmosphere
bar, mbar bar, millibar
cc/kg
volume of gas per kg of liquid. The volume of gas is calculated considering normal conditions
(T = 0°C, p = 1atm)
g/kg grams per kilogram
g/m
3
grams per cubic meter
mg/L milligrams per liter
ml/L milliliters per liter
Pa, hPa, kPa Pascal, hecto Pascal, kilo Pascal
ppb parts per billion, by weight
ppm parts per million, by weight (same as mg/kg)
ppm Vb
parts per million, per volume, barometric pressure referenced.
= %Vbar / 10,000
ppm Ve
parts per million, per volume, external pressure referenced.
= %Vext / 10,000
psia pound per square inch, absolute
V / V volume per volume (ratio)
Terms Meaning
Absolute pressure This is the total pressure in a system (i.e. relative pressure, plus atmospheric pressure)
Analog output A voltage or current signal that is a continuous function of the measured parameter.
ASCII
American Standard Code for Information Interchange. A standard character-coding scheme used
by most computers to display letters, digits and special characters.
Baud rate
Baud rate means transmission speed (Unit: bits per second, bps ), especially for RS-232/422/485
interfaces.
CIP Cleaning In Progress
Concentration The relative content of a component in a gaseous or liquid media.
Conductivity The reciprocal of electrical resistivity.
FIFO (First In First Out)
FIFO is a concept to describe the behavior of a buffer. It means the data which entered first will
exit first.
Headspace The empty volume above a liquid or solid in a closed container.
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