Rae MiniRAE Plus PGM-76, Руководство по эксплуатации и обслуживанию

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SECTION 4 PROGRAMMING IN HYGIENE MODE
4 - 22
4.7.5 Calibration for Other Gases
It is often impractical to carry a range of different standard
gases into the field for calibration. If the type of the organic
vapor to be measured in the field is known and the relative
sensitivity of this gas compared to the standard reference gas (
such as 100 ppm isobutylene ) for the PID instrument is
available, then one can calibrate the instrument using a standard
reference gas and then convert the instrument readings into
actual ppm of a specific gas based on the relative sensitivity,
also known as
calibration factor .
The calibration factor for a specific gas is defined as:
sensitivity to a standard gas
Calibration factor =
______________________
sensitivity to a specific gas
For example, when the PID sensor is exposed to 100 ppm
isobutylene gas, the instrument will measure say 10 mV from the
sensor. When exposed to 100 ppm benzene gas, the
instrument will measure say 17.5 mV. Then the calibration
factor for benzene, relative to isobutylene is :
10 mV
Calibration factor (benzene) =
______
= 0.57
17.5 mV
Appendix C contains a list of calibration factors for common
organic vapors. There are two ways to use these calibration
factors to obtain a calculated concentration of another gas: