English Dictionary

zero air

noun

atmospheric air specially cleaned so that it contains less than 0.1 ppm of hydrocarbon impurities; it then is usable in laboratory procedures such as versions of gas chromatography in which sufficiently pure air may serve as a carrier gas.

Zero air is used in analytical laboratories to ensure accurate measurements.

意味（1）

atmospheric air specially cleaned so that it contains less than 0.1 ppm of hydrocarbon impurities; it then is usable in laboratory procedures such as versions of gas chromatography in which sufficiently pure air may serve as a carrier gas.

For calibration, first pass a known range of concentrations of the gas through the gas chromatograph, for comparison with zero air that contains effectively none of the gas to be measured.