Gas detectors. Explosimeter – toximeter – oxygenometer

This article deals with the use of gas detectors in explosimetry and toxicometry. In these fields, the gas detector is a device designed to give an alarm when the atmosphere becomes explosive (presence of a combustible gas) or toxic (presence of a gas hazardous to health, absence or excess of oxygen). The flammable gas detector is also known as an explosimeter.

To accurately identify a danger threshold, the detector must perform a measurement: it measures the concentration of the gas present, or in most cases its partial pressure. This type of device is therefore used for atmospheric monitoring, not process control, which differentiates it from analyzers, which are more precise and therefore more expensive. It is most often used for industrial purposes, although there are also detectors designed for domestic use (methane or carbon monoxide leak detectors).

The use of microprocessors has extended the field of application to industrial hygiene, and even pollution control; it has become possible to store measurements, calculate averages over time... However, these measurements, which are often regulatory, require measurement uncertainties or specific measurement rules which cannot always be obtained or used with this type of device.

Performance requirements are set by the European and international communities (CEN – European Committee for Standardization – and IEC – International Electrotechnical Commission for Standardization).

Care should be taken when selecting such devices for measurements other than simple indications of the presence or absence of gas.