What Are The Chances?

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eagleray2003

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As mentioned by SeaHunter lets get some good constructive talk going on this.
What are the chances of getting bad air?
Other than smell or taste could bad air go undetected by the user?
Could there be health risks as a result?
 
The chances of getting bad air from a system that is well designed and maintained are incredibly low. I'm guessing all diving deaths are investigated, and air testing is standard procedure, but when was the last time you heard of a death from bad air?
Yes, injury and death can result from bad air, but hopefully these days shop owners are too afraid of pushing bad air to let that happen. Just one unsubstantiated rumour about bad air could cost a shop heavily I'd imagine.

Having said that, we had an instance a couple of years ago where multiple people on a dive boat who all got their tanks filled at the same place on the same day, complained of an oily taste and headaches. Upon removing the valves from a couple of tanks oil was found at the bottom - in one case it was about half a cup. All tanks had to be re-O2 cleaned. The shop owner was notified but denied that their equipment was at fault (but had it serviced two weeks later just before it could be tested by the ministry).
 
I agree in your comments that it is rare indeed that a diver had died from contaminated air as a direct cause, but must point out that unknown or known contaminants with in the breathing atmosphere can indirectly contribute to diving accidents and fatalities.

Our commonly known rules relating to time/depth and exposures are only based upon known gases at known ratios and concentrations. When an unknown or known contaminant is inadvertantly inhaled at depth, the affects can vary from lethal to incapacitiating. In this I mean that impaired judgement and an inability to fuction safely may be the result of being exposed to a contaminant.

Who denies or confirms that a diver's lack of judgement resulting in a death by drowning or injury wasn't the indirect result of breathing a tank with contaminants.

What is the long term effects of such an exposure?

In an IDLH environment such as diving, one must be very strict as to what is in their tank. Whether underwater, in a fire or inside a chemical filled hole the standards must be maintained.

Regulations, Specifications, Proceedures and Policies are put here for 1 reason only..to protect everyone's behinds.
 
eagleray2003 once bubbled...
As mentioned by SeaHunter lets get some good constructive talk going on this. What are the chances of getting bad air?

The way this question is phrased seems to me to assume that it is a random event. It is not usually. Good maintenance and a good setup makes it very unlikely. Poor maintenance and a poor setup (especially with gas or diesel powered compressors make it very likely.

Other than smell or taste could bad air go undetected by the user?

Carbon monoxide contaminated air would be undetectable to the user. I would imagine some other contaminants may be as well.

Could there be health risks as a result?

Yes. Not to be a smart ass but death is one risk if an undetectable contaminant was present. Also, long-term exposure of the lungs to organic chemicals cannot be good for you.
 
Ok, this may be stupid newbie question but - if you're diving in cold water, doesn't "wet" air have an awful good chance of freezing up parts of the reg (depends on reg, I guess). Joule-Thompson equation descibes the cooling of a gas as it expands, and it looks like there's a very real risk that the already-cold (say 4-6C) compressed air expanding in the first stage reg will drop below 0C and freeze out any water present. Or am I missing something here?

To answer part of the original question by eagleray2003, yes, there are some contaminants that have no smell or taste. Not many, though - the most likely toxic contaminant in compressor air is the oil from (or lubricants associated with) the compressor itself. We have the same problem when bubbling air to lab fish and invertebrate cultures - compressors can get pretty bad, although there are a few "contaminant-free" designs out there for labs - probably same for breathing air. More $$$, though.
 
When a breathing air sample is tested, the standards also require a maximum moisture content.
If the air sample is good, it means the moisture level is also acceptable for all scuba diving.
 
Both NAUI & PADI require quarterly air testing as per their respective agency standards or ethics. Quarterly would be ever three months.....how many shops do you know that follow that standard in Ontario?

The CSA standard refers to air tests every six months or after maintenance on a compressor. Some of the busy shops pump more air in three weekends than others do all year. Should the standard be changed to be in relation to the number of hours the compressor operates?

Depending on the version of Z-180 used the air is tested for Carbon Dioxide, Oxygen, Nitrogen, Methane, Carbon Monoxide, Nitrous Oxide, Non-methane hydrocarbons, Halogenated Hydrocarbons, dewpoint, Nitrogen Dioxide, Water Vapour, and Odour.

Well I have seen samples that contained Dichlorofluoromethane, Isobutane, Butane, 2-Methylbutane, Acetone, Pentane, 2-Methylpentane, 3-Methypentane, Hexane, Methylcyclopentane, Tolune, Ethylbenzene, Limonene etc...but they are not normally tested for. What are the exposure effects of these? What is the effect of breathing these at depth?

With regards to dew point and freeze faillure....will mold grow in a tank????????

Well thats enough ranting for me for now.....
 
Generally and for many years dive shops tested their air every year. Those that are members of an agency that requires quarterly testing will do the tests to maintain their membership. In the case of PADI, it costs about $1000 yearly to get and keep the 5 Star rating and quarterly submissions of positive air tests are required. The air tests cost about $200. Besides being necessary to keep the 5 Star rating, it's also good business and good insurance for the store.

Stores that pump a lot of air do not necessarily need more tests. The replacement of the filters and other maintenance of the compressor are based on it's use. Busy stores would be replacing the filters more often but, assuming proper maintenance is carried out, quarterly tests are sufficient.

Stores that don't pump a lot of air are possibly MORE likely to be a problem. They are less likely to spend any money on maintenance and on more frequent tests. It's kinda' like buying a chocolate bar at a tiny store that isn't busy compared to buying it at a busy store. At the busy store, the staff is checking and filling the candy bar section more frequently and the bars are fresh.
 
Mold will DEFINATELY grow in a scuba tank because there is a lot of air, hence oxygen available but, you'd have to be getting very wet air. Mold or any kind of biological growth requires much more water than is available in approved breathing air so, if your air comes from a good source, you won't have a problem.

There was a story many years ago that I can't confirm about a dive store owner who would put a dab of spit on the valve face to check for leaky valves before filling the tank. Then he'd fit the filler whip and fill the tank. Obviously the spit was blown into the tanks. The story goes that divers were getting ill even though the air was good. Finally someone spotted his practice and checked the tanks only to find they had a fungal growth on the inside from the spit.
Don't know if it's true but it sounds plausible .... and disgusting!
 
OK you Scubaboard experts!!
How can I have 4 posts in a row without an increase in the numbers of posts I've made?
 
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