Testing Recreational Dive Tanks

Dear Mr. Kerr,

It is with great pleasure that I have stumbled on your web site and CO detector from a link on the aeromedix.com web site. I am a scuba diver and family physician who is concerned about the air I breath often at up to 5 ATM pressure. The problem with scuba air station fills these days is the monitoring of air quality is poor. Twice a year here in Canada a fill station is obligated by CSA to send an air sample out to an accredited lab. The fill station owner though is not obligated by law to act on a contaminated sample and can continue to fill tanks. He does not have to send his lab reports to any government office I believe unless he has employees who complain to the Ministry of Labor. This is a less than ideal situation.

A recreational diving safety magazine called Alert Diver published an article in 1998 stating that two of the United States  largest air testing labs, Lawrence Factor and TRI, found that between 5 to 8 percent of their air station samples tested over the 10ppm level and several were found to be in the 100 to 200 ppm range. I called one of these labs this week to clarify those figures and was told that samples directly from scuba fill stations greater than 10 ppm are about 3 percent which I still consider far too high. Most of the failures come from fire stations where they might have an older gas compressor or improperly maintained electric compressor. I feel for the fireman that is going to check out a CO alarm and puts on his SCBA unit which has 200 ppm of CO in his breathing air!

The problem in scuba is we breath air under pressures much higher than atmosphere so the partial pressure of CO would be greater at depth and one would want to keep CO contamination to a minimum in scuba air. Many dive shops particularly in places like Latin America and here with the portable compressor use gas compressors where CO can enter the fills.  Even with the electric compressors an improperly placed intake pipe or improperly maintained compressor can lead to CO in the fill.

It is with that background information that I began a search for a product to allow me to check my own fills out in the field before entering the water and decide for myself if my tank is free of CO. In the past there were several scuba dedicated products but these were mainly the gel tubes or colormetric devices and most of these companies have gone out of business.  Recently I was looking at an industrial handheld unit by BW Technologies which costs $375 US and needs to be calibrated often. This is really out of my price range and would not be readily accessible to the recreational diver (single tank, depths less than 130 ft (5ATM)) at this price.


It is with pleasure then I came across your product and would appreciate greatly if you could comment on how I  plan to use your detector.  The best scuba fill would have no CO in the tank but the current standard is to allow up to 10 ppm and the US Navy allows up to 20 ppm. I am interested in a detector which is battery powered, portable, and most importantly quantitative and sensitive in the 0 to 100 ppm range.  Any tank which was found to have more than 20 ppm I would not dive with. An elevated CO is often just a marker for other contaminants like hydrocarbons.

My sampling would be done as follows.  I would put your device in a plastic bag with my scuba mouthpiece in the bag and gently purge air from the tank via the mouthpiece into the bag until the air in the bag is replaced by tank air. I would then remove the mouthpiece and seal the bag. At no time would the device be exposed to any moisture or high pressure air. I would then take a reading on the tank air in the bag. This in fact was how I thought I would use the BWT handheld device and they said that would be fine. Many of the oil and gas workers do this each morning to check their H2S detectors.

There basically is no information on the physiology of CO contamination of breathing CO at depth. The number of deaths attributed to CO poisoning in recreational scuba appears to be very low but some think this may be under reported as many deaths are just reported as ‘drownings’ and the air is not checked for CO unless a suspicion is raised. Not all states and provinces require mandatory testing of tanks in dive accidents or deaths.

In any case I would just like to have a way to lower the risk of CO contamination in my air fills. Let me know what you think about the use of your device in this fashion. You know if it works and is reliable there are something like 3 million recreational divers in the United States not to mention all the technical guys who also need such a device. Could be a large market.

Looking forward to your reply. Are there any Canadian distributors?

Thank you.
Yours truly,
P. M.
Toronto, Canada


Thank You, for your E-mail.
I am Extremely Interested in this Problem that you brought to my attention, which  I was NOT aware of previously.  My Canadian Associate, along with being a Gas Detection Expert, is also a Firefighter, … and a Scuba Diver.
I have forwarded him your E-mail, and I am sure that he will be in Contact with you shortly.

His name is Jim Mackie, and you will find some INFO on Jim on my Website under “Recommended Professionals”.  We WILL work with you on finding the Best Possible Solution to this C O Problem.

Thank You again for bringing this to our attention,
Best Regards,
George E. Kerr, President


And in a follow up letter from Jim Mackie:


Please contact me on my cell phone.

I have discussed this with a fellow diver who is an investigative reporter from the Toronto area and we are both interested.

I have run some preliminary tests on stored air from three different sources and was very surprised to find 4 ppm background in the first sample.

I will discuss this further with you when we speak.


Jim Mackie

Any new development on the scuba CO detector ?



Dear M B
As I believe I told you previously, the “Major Problem” is that the Compressors being used, [in many cases are portable gas powered units], are creating excessive C  O in the Area where the AIR TANKS are being filled.

Their is an “Existing” product to “Test” the “Filling Process”; however, since there is NO “Legal Requirement” that has EVER been enforced, it simply isn’t being done.

You can get more information on this C  O Product by contacting: Sam Summers at: gases101@hotmail.com


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CO Experts
19299 Katrina Lane; Eldridge Missouri 65463-9102
Tel: 1-888-443-5377 Fax: 1-888-436-5377

CO Experts
19299 Katrina Lane – Eldridge Missouri 65463-9102
Tel: 1-888-443-5377 Fax: 1-888-436-5377