Tonhil
When serving in the fire service I was told the air in our BA sets was of medical standard
Air Quality Standards ISO 8573.1 & ISO12500 set out the different standards of air quality.

Figure given above will be for your cylinders if they are 200 bar

Full description below:




Taking into account the requirements of the National Foreword to BS EN 12021,2 the standards for breathing air are detailed below. All measurements are at atmospheric pressure.
■ The oxygen content shall be in the range of 21% (+_ 1) by volume (dry air).
■ Lubricant content (droplets or mist) shall not exceed 0.5 mg.m­3.
■ Carbon dioxide content shall not exceed ­3
500 ml.m (500 ppm).
■ Carbon monoxide content shall be as low as
­3
possible but not exceed 3.5 mg.m (3 ppm).
■ The air shall be without significant odour or taste.
■ There shall be no free liquid water.
■ The maximum water content of the air measured
at:
­ a compressor system outlet for filling cylinders,
should not exceed 25 mg.m­3.
­ a cylinder outlet, cylinder pressure from 40 to
200 bar, should not exceed 50 mg.m­3.
­ a cylinder outlet, cylinder pressure >200 bar,
should not exceed 35 mg.m­3.

Phil

MEden380, HeO2, nickygee, many thanks.
As far as I can tell the compressor has been serviced, however BA sets are freezing up intermittently to the extent that at times valves cannot be closed such is the frost build up and there are reported incidents of loss of air at demand valve!!!