Selection And Use of Portable Gas Detection Technology for protection of workers in confined spaces - Patrick Hogan

Confined space entry is the most hazardous working environment for an operator because poor ventilation means the greatest chance of a build up of hazardous gas. Sometimes, in utility and construction industries for example, the operator is working in a cramped underground area that is wet, dirty, contaminated with pollutants and prone to changes in humidity and temperature. Portable gas detectors are small, lightweight, battery powered devices that can be worn by those who perform their job in hazardous areas where there is potential exposure to flammable and toxic vapours. The devices use chemical sensing methods to sample the air in the environment and raise early warning alarms that alert the user to the presence of three major threats: flammable gases; toxic gases and the diminution of breathable oxygen.

Selection criteria
The ideal portable gas detector is of robust design, waterproof, lightweight, has a long battery life, detects and alarms hazardous levels quickly and is able to respond to all the likely hazardous gases (including hydrogen) whilst remaining immune to other species that could contaminate or adversely affect the actual reading of the target gases. Especially with large fleets of gas detectors, selection criteria may also include overall cost of ownership and technical features that reduce the cost of maintaining the devices in calibrated, full working order. Principally, users of gas monitoring equipment are concerned that the detector is always available for gas detection and is not impaired in any obvious (e.g. battery dead) or undetectable (e.g. a sensor grille is blocked) way that would lead to workers not being protected. Health and safety legislation and standard operating procedures do not allow entry into confined spaces without such sensing protection. The consequence of the unit not being operational is often expensive down time for the operator or contractor.

Portable gas detection technologies
Modern portable gas detectors use a range of sensing technologies that are now commercially available for inclusion in portable devices. This review is focused specifically on the demands of confined space entry in aggressive working environments and how well the available technologies compare with one another.