Gas monitoring equipment

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1. What is it for?

Gas monitoring equipment is designed to detect and warn you of potentially hazardous atmospheres in confined spaces. These ‘early warnings’ should help you decide:
 

• whether it is safe to enter a confined space; and
• if the atmosphere is safe for you to continue working inside it.

It is especially important for monitoring fumigation chemicals when inspecting or unpacking containers.

For handling of fumigated containers, see: 

• Safe working in docks and freight areas - Examining freight and containers
• Dangerous Substances - Fumigants

2. What types are available?

Two distinct types of gas monitoring equipment are available.

Oxygen meters: These measure the percentage of atmospheric oxygen, which should be approximately 20.9 % of the air. They will give you an audible and visual warning if the level: 

• drops below 19 % (a danger to life); or
• exceeds 23 % (a fire/explosion hazard).

They are equipped with an earphone for use in noisy areas, an aspirator to allow remote sampling and a waist clip.

Remember: oxygen meters only measure oxygen levels — not other gases.

Multi-gas personal monitors: These will detect hazardous gases at the same time as monitoring the level of atmospheric oxygen. They provide a warning in cases of: 

• oxygen deficiency (less than 19 % in the air);
• oxygen enrichment (more than 23 % in the air);
• dangerous levels of methane (potentially flammable and explosive); and
• dangerous levels of hydrogen sulphide (poisonous and potentially flammable). 

3. How do I use it?

Use it to test the atmosphere, both before you enter a confined space and while you are inside. You must not enter a confined space if you have no gas monitoring equipment available. When you are working in a confined space, if the alarm sounds you must immediately put on your ELSA (emergency life support apparatus) and leave the area. Never continue to work while wearing ELSA.

Remember: gas monitoring equipment is highly specialized apparatus. It must be used only by people who have been trained how to use it. 

4. How do I look after it?

Oxygen meters

Care and maintenance instructions are supplied with oxygen meters. You should follow them strictly. The meter is powered by a zinc carbon battery, which should provide up to 400 hours of continuous use. A low battery warning is provided and a replacement (of the same type) should be fitted as soon as it is activated.

Multi-gas personal monitors

These monitors are very sensitive and should be calibrated in accordance with the manufacturer’s instructions in order to remain effective.
The unit should be returned to the manufacturer for maintenance regularly.
It is recommendable to keep maintenance records at the station for five years.

Remember: NEVER attempt to replace the battery while you are in a confined space.

The guidance contained in this section intended to serve as a general reminder of the risks that are sometimes encountered during the examination and sampling procedure and of the safety equipment that you should use and precautions that you should take.
You must refer to the legislation and the guidance of your national administration for more information.