Ventilation is the subject of an article in the August issue of International Mining magazine. Gas detection is an important consideration in ensuring best ventilation practice. In the paper Choosing the best detection technologies for measuring combustible gas and VOC vapours, Bob Henderson President of GfG Instrumentation in the USA explained that “No one single sensor (or type of sensor) is capable of detecting all types of dangerous gases and vapours. This is why workers who may be exposed to multiple hazards use instruments with multiple sensors installed.
“The most commonly used sensors are for the measurement of combustible gas, oxygen, carbon monoxide and hydrogen sulphide. The majority of multisensor instruments are equipped with at least these four sensors. However, in many cases, these basic sensors are not capable of measuring all of the atmospheric hazards that are potentially present.
“The sensors utilised in portable gas detectors are extremely good at detecting what they are designed to measure. The problem is that users are frequently unaware of the limitations, and use the sensors in ways that result in inaccurate readings. It is critically important for instrument users to understand what the sensors in their instrument cannot properly measure as well as what they can.
“There is an extremely wide range of technologies and types of sensors available for use in portable multi-sensor instruments. Just because one type of sensor does not work for a particular gas does not mean there are no alternatives.
“The only limitation is that the instrument must be sufficiently flexible to make use of the most appropriate detection technologies.
“Oxygen, carbon monoxide and hydrogen sulphide sensors are designed to measure a single type of gas. There is very little ambiguity in the readings these sensors provide. The only gas an oxygen sensor responds to is oxygen. Electrochemical sensors designed to measure a particular gas may not be quite so specific. Although sensor manufacturers design their products to minimise responsiveness to gases other than the one they are supposed to measure, no design is perfect. For instance, CO sensors may also respond to hydrogen as well as to the vapours produced by alcohols, solvents and other volatile organic chemicals (VOCs). Since most interfering effects are positive, the
possibility that the sensor may occasionally provide higher than actual readings for CO is generally not regarded as a safety concern. It just means that workers leave the affected area a little sooner.”
GfG’s Microtector II G460 is a light and robust gas detector, a development of the proven Microtector II G450. The key features are retained – smart, interchangeable sensor technology, low cost of ownership – but extra functionality is now added. The G460 measures up to seven gases simultaneously in ambient air for increased workplace safety. The sensor slots can be equipped individually. Different detection principles are available for optimal measuring results.
The G460 is certified to EN 60079-29-1 (combustible gas performance) EN 50104 (oxygen), EN 45544-1 (toxic) and EN 45544-2 (toxic). The most common sensors detect O2, H2S, CO, CO2 and combustible gases. Additional sensors are available for NH3, HCl, PH3, HCN, NO, NO2, SO2 and a variety of other gases.