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HAZARDOUS SUBSTANCES


workers were exposed to unacceptable risks.


The only way to check that a gas detector is working and can respond to the target gas is by function testing or ‘bump testing’. This involves the use of a special test gas mixture containing specific quantities of each of the gas components that the equipment is being used to detect. Ideally the test should be carried out by the user of the equipment each day before it is used, or it may be carried out by a technician in a calibration workshop.


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damage, the sensor ports may become obstructed or damaged, or there might be a manufacturing problem.


If the sensors fail, the user has no way of knowing. There’s no alarm to signal that the equipment is not working and, crucially, the user will be unaware that a gas leak or a hazardous gas build-up has occurred. It is also important to note that catalytic flammable sensors and electrochemical sensors fail to zero output – meaning that the instrument reading remains at zero when hazardous gas is present.


Over the last two years, there has been a number of high-profile incidents where things have gone tragically wrong. While not all relate to gas detectors failing, they highlight all too clearly the potential hazards.


In November 2012, a UK firm was fined for putting


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employees in danger by allowing them to work in confined spaces without relevant training or safety measures. In a statement, the Health and Safety Executive said its inspectors: “found that a gas analyser, used to ensure that the atmosphere in the pit was safe, had not been calibrated to ensure its accuracy.”


In 2010, 29 workers were killed at a coal mine in New Zealand following a blast caused by a methane gas explosion. A Royal Commission report into the incident said: “the tragedy was preventable but administrative and regulatory reforms are urgently needed to reduce the likelihood of further tragedies.” The report said the systems and infrastructure necessary to produce coal safely had not been completed, and that


“OVER THE LAST TWO YEARS, THERE HAS BEEN A NUMBER OF HIGH-PROFILE INCIDENTS WHERE THINGS HAVE GONE TRAGICALLY WRONG.”


Gas detection equipment is used across a wide range of industries including chemicals, utilities, water, tank repair, oil plants and petrochemicals, mining, pulp and paper and pharmaceutical laboratories. It also applies to other industries where employees work in a confined space, or in any environment where there is the potential for an explosive or toxic atmosphere, or a risk of oxygen concentrations being depleted to harmful levels.


‘Bump testing’ is easy to carry out, and manufacturers typically include a methodology for performing a functional check in the user manual. So, there should be no excuses.


Being lightweight, function testing can be carried out easily in the field or in a


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workshop. No tools are needed to connect the gas control equipment to the canister, and these can range from the largest, holding 110 gas litres, to the smallest 12 litre aerosol. They are compliant with current European standards and legislation, robust and reliable, and offered with gas control equipment suitable for either diffusion instruments, or units fitted with internal pumps. Custom and standard gas mixtures and pure gases are available, providing mixture accuracy, optimum stability and maximum shelf life.


Hard statistics are rather thin on the ground, but there is an abundance of stories about poor or absent safety procedures, with gas detection equipment being


dug out of storage and not being checked. Every year gas-related accidents mean people die unnecessarily and property is damaged.


The message is simple: ‘bump testing’ must be included in every gas safety system. Carrying out regular before-use checks will give operators the confidence and peace of mind that the equipment they are relying on is actually working. Without a ‘bump test’, they won’t know it isn’t working, until it doesn’t. And if the atmosphere is toxic, flammable or oxygen deficient, that could be too late.


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