What is a Correction Factor (CF)?

The Correction Factor (CF) is the measure of the sensitivity of a PID to a specific gas. The CF will only be used if you have an instrument calibrated with one compound when you are sampling another. The relationship between the calibration gas and the alternative compound determines the sensitivity of the PID to that gas, and gives you the Correction Factor.

For example with an Isobutylene-calibrated instrument, a measurement of toluene will read high. This is because the response of the PID to toluene is different compared to Isobutylene. This difference is the response/ correction factor.

Correction Factor Example:
For toluene the correction factor is 0.5. Therefore if the instrument reads 100ppm and you know it is toluene, the correct value is 100ppm x 0.5 = 50ppm

Most manufacturers publish a list of response/correction factors for several hundred different compounds. These factors are now usually built in to the PID to allow users to correct the readings.

Example correction factors:
Acetone- 0.7
Ammonia - 8.5
Benzene - 0.5
Butadiene - 0.85
Diesel Fuel - 0.75
Ethanol - 8.7
Gasoline - 1.1
n-Hexane - 3.3
Styrene - 0.45
Toluene - 0.51
Vinyl Chloride - 2.2
Xylene - 0.43 

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