The most important parameters in specifying Breathing air quality are:

• Carbon Monoxide
• Carbon Dioxide
• Oxygen
• Total Hydrocarbons
• Oil Mist & Particulate Matter
• Dew Point
• Viable Count.

The importance of clean Breathing Air is to sustain life and maintain good health.

The Compressed Gas Association sets quality standards for Breathing air is GRADE D (ANSI/CGA G-7.1'97)

Carbon Monoxide – CO is the most dangerous contaminant in Compressed Breathing Air. CO enters the Breathing Air System through the air intake, or is produced by overheating of piston type compressors. The air intake must be placed away from engine exhaust or other sources of Carbon monoxide. Headaches, dizziness, unconsciousness and death can result from exposure to elevated CO levels. Both CGA G-7.1 Grades D list a 10 ppm Maximum CO content. If a good air supply and a properly functioning, efficient compressor are in use, CO levels will be less than 1 ppm. Detectable CO levels above 1-2.5 ppm are abnormal and require further investigation.

Carbon Dioxide - Normal CO2 levels in outdoor Air (i.e. 200-400 ppm) or indoor Air (i.e. 500-2,500 ppm) are not considered hazardous. However, Compressed air with CO2 levels that are within the “indoor air range” can create problems in SCBA applications. Some compressors are equipped with filters to reduce CO2 levels. CGA G-7 lists a 1000 ppm maximum for Grade D air. High CO2 levels in Breathing Air tanks can produce many of the same symptoms as CO poisoning. In addition, high CO2 levels increase breathing rates, which shorten SCBA usage time. One of the most common causes of Breathing air quality failures is excessive CO2 content.

Oxygen – The O2 level in Compressed Air derived from natural or synthetic air should fall within a narrow % range.CGA G-7.1 lists an allowable 19.5-23.5% range for Grade D.

Total Hydrocarbon Content – Several thousand types of organic gases and vapors are potentially present in air. Volatile organic contaminants can be man-made such as Gasoline vapour, Exhaust fumes, cleaning solvents, Lube Oil Vapour or the result of biogenic activities such as Marsh Gas, Mold, Mildew. Many organic vapors are hazardous and/or have irritating odors. A common feature of these volatile organic materials is that they contain 1 or more hydrogen (H) + Carbon © atom. Since it is impractical to measure each type of organic contaminant present, they are measured as a group and described as “Total Hydrocarbon Content”. Compressed synthetic Breathing Air can have TH Values of less than 1 ppm.

Oil Mist and Particulate Matter – Air Compressors, including non-lubricated models, utilize some type of lubricating fluid. Many compressors contain either mineral or synthetic lubricants (e.g. oil). Even with particle, oil and odor filters, it is still possible for oil or fine particulates to contaminate Breathing air if a mechanical malfunction occurs or there has been poor maintenance. CGA Grade D 7.1 lists Breathing Air Oil mist and Particulate Matter of 5 mg/m3. Detectable Oil levels is above 0.1 – 0.3 mg/m3 are abnormal.

Water Vapour and Dew Point - The Dew point temperature or Saturation temperature can be defined as the temperature at which condensation or moisture begins when moist air is cooled. The amount of water vapour that gets into Breathing Air depends on the intake air level and filter efficiency. Breathing Air is required to be dry enough to prevent malfunctions due to internal condensation or icing caused by expansion cooling past regulators. High Water levels can also inhibit catalysts that convert CO into Co2. CGA G-7.1 does not list a Water vapour and Dew point limit for Grade D.

Viable Count- For Breathing Air System, Viable count should be <100CFU.< /p>