Air Analysis:  Is It Necessary?

A Quick Summary Bulletin #2

Analysis of compressed air is the best way to discover any immediate problems and to avoid surprises. Routine testing also demonstrates to your clients that you have a Quality Assurance program that is designed to prevent surprises. Other reasons for checking the air include PADI requirements, certain state requirements, and OSHA general safety orders.

What You Cannot See Can Hurt You

One of my favorite stories:  In 1997 I spent a week in the Caribbean where some shops have their own compressors. One of the shops I visited told me that they had a testing program. When I asked them what it was, they pointed to a local gentleman who’s job it was to smell the air, flow some onto a white cloth and change anything that looked suspicious. I told him that that was good, but when I asked him about hydrocarbons and he said, “what’s that”? I asked him what carbon monoxide smelled like and he shrugged his shoulders. I asked him if he ever had the air analyzed, ….. and they asked me to leave. Depending totally on filter efficiency and supplying air without an effective air checking program is dangerous. We all know people who have had their vacations ruined by diving with tainted air. If you get headaches or feel nauseous after a long dive, it could be methane, elevated Carbon Dioxide, Carbon Monoxide, or the breakdown products of overheated compressors. It is not uncommon for gas leaks or restaurant exhaust to end up in the intake of compressor systems where it will concentrate; filters will not pull it out. Carbon Dioxide can also build up in the air, but for an entirely different reason. And then, of course, we have the possibility of oil mist or oil oxidation products. You can't detect them when the air goes from the compressor or storage flasks right into the SCUBA flasks. The point is, without a test of some sort, you will never know what is in the air. Organizations not performing scheduled air analyses, honestly believe that their QA program can discover as well as prevent problems. Although the great majority of air systems we test consistently produce good clean air, here are some documented case histories of our own experiences which are a reminder of things that can go unobserved if all you do is change air filters and check the CO.

  1. A store in a small town  had its compressor overhauled but not tested for contaminants prior to filling SCUBA flasks.  The tank of air one diver received contained over 400 ppm of carbon monoxide in it; that diver died underwater. The point is that even a simple $10  test with a color indicator tube (Drager tube)*  would have prevented this accident, but the store owner put all his faith (and future) in assuming that an overhaul meant that the air must be ok.
  2. A group of divers became sick despite no odor, no evidence of oil, and normal readings on the system’s CO detector.  Changing filters and lubricants did not solve the problem.   Laboratory analysis revealed methane from a leaking city gas pipe. Another case with similar symptoms, identified paint solvents.
  3. I spoke to two ladies that are experienced divers. They said that the air the air in their flasks did not have an odor, but after a short dive they became "sicker than they had ever been", and would never dive with or recommend that dive operation again.
  4. Changing filters was routinely done in this store, but a combination of overheating and extending the filter replacement time caused pyrolysis of fugitive oil. A training dive was cancelled when the entire group became sick from that air. Another diver ignored the odor, and surfaced experiencing blurred vision, muscle impairment, and convulsions which required 2 days of oxygen therapy in a hospital.
  5. Our sampling program at the USN Dive School discovered oil mist escaping the filters when sampled at production flows. Our early warning allowed the compressor to be repaired before harm came to any diver.
  6. In separate incidents, desiccant disintegration, rust debris, charcoal dusting, and cylinder destruction were not visible during daily charging of flasks, but were discovered during our sampling and analyses. See the evidence on page 2 of sampling for oil mist plus particulate.
  7. A portable compressor was working fine without any apparent symptoms of mechanical failure. A quarterly check discovered a large amount of iron particulate in the product air. Shut down and inspection of the compressor revealed that the piston was gouging the cylinder walls. Discovery of the debris resulted in the compressor being removed from inventory. This likely prevented a dive team from being injured from the debris it was producing.

It is Good Business

Finally, air analysis can have a significant effect on your business, even if you are not required to do it.  When you post our lab report at your charging station, you are advertising your commitment to a quality service.  The feeling of trust can begin or end right there. *ALWAYS REQUIRE YOUR MECHANIC TO CHECK THE AIR FOR OIL,  PARTICULATE, AND CO AFTER ANY REPAIRS. Contact us ! © 2010  Analytical Chemists, Inc.