Keep safe when using gas detectors

Sadly, there has been a fatal incident following misleading gas detection readings. An explosion occurred when hot works were carried out on the basis of a misleading reading for flammable vapour.

The gas detector was not calibrated correctly for the type of gas present. The key cause of the accident, however, was that flammable vapour had absorbed onto the inner surface of the sample tube before it could reach the gas detector, thus producing a lower reading than it should have and therefore misleading the operator.

HSE safety alert

To prevent this terrible accident from happening again, the Health & Safety Executive (HSE) has issued a safety alert  – ‘Failure to detect dangerous gas/vapour due to incorrect specification of sample tube’.

All gas installers should read this alert and make sure they are using their gas detector correctly for the type of gas and application they’re working with.

How can I keep safe?

We recommend you read the safety alert in full.

Here are the main points you must consider when carrying out hot works in environments where flammable or toxic vapour may be present:

  • The gas detection system used must be suitable for the intended purpose
  • Check that the detector you are using has been calibrated correctly for the substance to be measured
  • Function check (‘bump test’) gas detectors before each day’s use
  • Bump test the sample tube as well as the substance that needs detecting
  • Make sure the sample tube is as short as possible
  • Check the response time in accordance with the gas detector manual, or where no time is specified, 3 seconds per metre of sample tube. Where the response time exceeds this the arrangement should be considered unsatisfactory.

The HSE alert contains further details and references British Standards, plus more information about the selection and use of flammable gas detectors.

It is very important that you review your own gas detector usage for both flammable and toxic gases to keep you and your colleagues safe.

To read full alert, click here.

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