The possible combinations in types of calibration gases and span gases are numerous. But how to choose the correct calibration/span gas that fits your gas detector? In this months blog, we advise you on how to choose the right substation for calibration of your gas detector. No matter if it is a single gas – or multi-gas detector.
Which type of calibration gas should be used for single gas detectors?
As the detector name reveals, a single gas detector should be calibrated with a single gas. This type of gas could be a flammable gas, oxygen gas or toxic gas. The type of gas used for calibration of the single gas detector is not by definition brand related. For example; a single flammable gas detector needs to be calibrated with a single flammable gas which is methane calibration gas or iso-butane calibration gas in most of the times. Or a single gas oxygen detector could be calibrated with pure nitrogen calibration gas or with oxygen calibration gas.
“a single gas H2S detector needs calibration with hydrogen sulfide calibration gases”
If you are using a single gas CO detector, this detector needs calibration with carbon monoxide calibration gases, and a single gas H2S detector needs calibration with hydrogen sulfide calibration gases. There are many specific toxic single gas detectors which each requires their own particular toxic calibration gas or span gas for calibration.
Which type of calibration gas should be used for a multi-gas detector?
In comparison with single gas detectors, multi-gas detectors are calibrated with calibration gases mixtures which are brand related. Every brand multi-gas detector needs calibration with its particular gas mixture. This has resulted in the fact that there are specific calibration gas mixtures for multi-gas detectors of brands like Riken Keiki, MSA, Dräger, Crowcon, GMI, BW Technologies, RAE, etc. These calibration gas mixtures are most of the times 4-gas mixtures including carbon monoxide, hydrogen sulfide, flammable gas and oxygen in balance nitrogen. The flammable gas type in the various gas mixtures is most of the times methane or iso-butane and sometimes propane. The flammable gas concentration of each specific flammable gas is always a %Vol which is equal to 50%LEL. Where gas mixes of different brands differ from each other are the height of the ppm concentrations of toxic gases such as carbon monoxide and hydrogen sulfide and the height of the %Vol concentration of oxygen.
How many litres of calibration/span gas do you require?
Disposable calibration gas cylinders are available in 10, 34, 58 and 110 litres. Single gases are available in all the sizes mentioned above. Gas mixtures are only available in volumes of 34, 58 and 110 litres. Which cylinder size should be used is in principle free to choose. The larger the cylinder size, the more content, the higher the price.