Crowcon - Detecting Gas Saving Lives
28 July 2016
Deadly Sin No. 6 – ignoring alarms

Ignoring alarms is Crowcon’s sixth in the series of Deadly Sins of Gas Detection. Alarms may be ignored if they go off so frequently that they become a source of annoyance rather than a vital piece of safety equipment. However, there have been incidents when a history of such spurious alarms has led to the detector being ignored or switched off, with disastrous results.

A lucky escape…
As a gas detection company, we hear of or witness first hand instances where alarms have been ignored or disabled.

In one incident, a national Health & Safety Authority were called in to investigate a laboratory using nitrogen. In this case, an oxygen monitor had gone into alarm, which should have been sufficient warning to the laboratory technicians that something was wrong. Rather than take appropriate precautionary actions, the technicians switched the monitor off at the mains. If the monitor had been installed according to the manufacturer’s instructions, this would not have been possible, but this was not the case. The upshot was the technicians collapsed due to low oxygen levels and had to be rescued. By extraordinary good fortune, nobody died.

A cover up…
Other instances include, in an environment where low levels of toxic gas were not unusual, a reset button on a control system being taped over.

This meant the button was permanently pressed in and the system was not able to go into alarm. In the event of a serious and dangerous gas escape, the system would be unable to alert workers to the danger.

Similarly, paper cups over gas detectors have been used for the same ill-judged and dangerous reason.

A deadly environment…
In a another laboratory establishment involving a nitrogen leak, the detector was working, the alarm was sounding and the control system, through the window showed 13% oxygen – a rapidly lethal environment. However, the alarm was ignored and everyone went about their normal business until a visiting service engineer alerted the manager.

Alarms should be alarming!
If alarms are going off so frequently that they are being ignored, then the situation needs to be addressed. Alarms being ignored has led to fatalities in the past.

To determine this, a review of the specific operational conditions to evaluate appropriate alarm setting is advisable. The default manufacturer alarm settings are often retained by the user, but for toxic gases, these are not appropriate for every site. It could be that alarm levels should be raised. If alarm levels are appropriate and the instrumentation is in good working order, then you could well have an even more serious safety issue.*

Setting things right
When gas alarms (or any other alarms for that matter) are being ignored, it is imperative to recognise that something is wrong. If there is not a genuine gas alarm situation, the equipment may be faulty or the alarm levels inappropriately set. In any case, the situation needs to be remedied if an accident is to be avoided. Employees cannot rely on their senses to distinguish what is in the atmosphere.

*For more information on this issue raised in this article, read the HSE’s review on alarm setting for toxic gas and oxygen detectors.

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