Why is Breathing Air Testing necessary?
Breathing air testing to BS EN 12021:2014, also known as compressed air quality testing is necessary to ensure that the air supplied to a worker’s air-fed helmet is of suitable quality. By suitable quality, we mean that it does not contain any contaminants at levels that can harm the user.
Which contaminants are specified in Compressed Air Quality Testing to BS EN 12021:2014?
BS EN 12021:2014 specifies the compressed air quality testing contaminants as carbon monoxide, carbon dioxide and oil mist. In addition, the breathing air testing sets requirements for the amount of oxygen, water, the water vapour dew point and the odour and taste of the air supply.
Where do the contaminants in the air come from?
The breathing air testing specifies several hazards. These enter the air in the following way:
The air intake of a compressor may draw in Carbon dioxide and carbon monoxide from an outside source. Carbon dioxide is an asphyxiant and carbon monoxide is toxic because of the way it reacts with the breather’s blood.
A failing air compressor pump or failing filtration can cause oil in the air line. This gives rise to toxic volatile substances in the air.
The compressed air quality testing measures the amount of oxygen in the air because a dryer malfunction can reduce the oxygen to an unsafe level.
Water and water vapour dew point measurements are important to prevent the condensation or freezing of water in the air line. This could disrupt the supply of air to the user.
How often is breathing air testing required?
Changes in the compressor and filter performance can happen rapidly. For this reason, the HSE require that the test is at least every three months. For rarely used equipment they require compressed air quality testing before each use. Employers must store the records of these tests and repairs for a period of at least five years.
BS EN 12021:2014 Limits
The purpose of the test is to make sure that the control measures put in place by the employer, such as inline filters, are delivering the air quality required by BS EN 12021:2014. In summary, BS EN 12021:2014 sets these limits for the breathing air testing:
- Oxygen must be at 21% ± 1%.
- Carbon monoxide must be as low as possible and must not exceed 5 ppm.
- Carbon dioxide must not exceed 500 ppm.
- Oil mist and vapour must not exceed 0.5 mgm-3
- Odour/taste – Without significant odour or taste.
- Water (liquid) – 290 mgm-3 at 5 bar and 20oC.
In addition, the compressed air quality testing must show a dew point low enough to prevent condensation and freezing. In particular, the dew point of the air must be at least 5oC below the lowest temperature that the operators use and store the equipment. Furthermore, the pressure dew point must not exceed -11oC where the conditions of usage and storage are unknown.
The frequency of the breathing air testing should be based on a risk assessment. However, it should take place at least every three months. This should be more often when the quality of air cannot be assured at these levels.
Further Information on compressed air quality testing is available below
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