The importance of clean breathing air to sustain life and maintain good health is well known. The dangers associated with breathing contaminated air are also well known and especially critical when using SCBA tanks in emergency situations. Some of the common Air Contamination Sources are listed below.
Sigma Sensing has individual solutions for each contaminant or solutions for monitoring multiple contaminants.
Breathing Air Carbon Dioxide (CO2) Contamination
Normal CO2 levels outdoors (i.e. 200 – 400 ppm) or indoors (i.e. 500 – 2,500 ppm) are not considered hazardous. However, compressed air with CO2 levels that are within the “indoors range” can create problems in Self-Contained Breathing Apparatus (SCBA) applications. Some compressors might be equipped with filters to reduce CO2 levels. CGA G-7.1 lists a 1,000 ppm maximum for Grade D and a 500 ppm maximum for Grade E air. High CO2 levels in SCBA 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 SCBA air quality failures is excessive CO2 content.
Breathing Air Carbon Monoxide (CO) Contamination
Carbon monoxide (CO) which is termed a toxic asphyxiant, is a colorless, odorless gas that is invisible to the human senses and ranks as the most dangerous compressed air contaminant. Low ppm doses of carbon monoxide can cause headaches and dizziness High doses can be fatal. High-pressure compressors are often equipped with a catalyst which converts CO into much less toxic CO2. Both CGA G-7.1 Grades D and E (the most widely recognized SCBA air quality grades) list a 10 ppm maximum CO content. European Pharmacopoeia lists < 5 ppm (v/v).
Breathing Air Water (Dewpoint) Contamination
The dew point is the temperature at which water vapor will start to condense from air. This value depends upon the air’s water vapor content and pressure. The water vapor content of intake air ranges from saturated to very dry.
Breathing Air Oil Contamination
Oil is a major contaminant in systems using lubricated compressors. In reciprocating compressors, lubricating oil applied to cylinders causes small droplets by the shearing action of the piston to enter the air system as a mist. Oil mist can cause breathing discomfort, nausea and pneumonia, and create unpleasant taste and odors. Centrifugal compressors are “oil-free compressors”, but the term refers only to the compression chamber, not the compressor system as a whole, or the resulting compressed air quality.