What Are The Chances?

[eagleray2003]

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?

[Marvintpa]

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).

[SneakyB'tard]

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.

[Goldminer]

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.

[cat]

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.

[seahunter]

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.

[Bubble Boy]

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.....

[seahunter]

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.

[seahunter]

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!

[seahunter]

OK you Scubaboard experts!!
How can I have 4 posts in a row without an increase in the numbers of posts I've made?

[Jonathan]

because it does it dynamically. If you look at your first post ever and last post you will have the same numbers of posts and status.....

[earlj]

Please explain this in layman's terms.

[fredk]

Prpper maintanence is key,spending a couple hundred dollars every month or so in the busy season for oil and various filters is cheap in comparison to what it could cost not to do the maintanence compressors are not cheap nor are lawsuits. I have in the middle of summer stopped pumping air for a day or 2 waiting for filters to arrive, I really don't need the $5.00 that bad to chance pumping sub standard air or have a diver or staff member get injured.

[seahunter]

Yes please Jonathan explain what you mean by 'dynamic posting'. I take it from your reply that the total number of posts I've made is equal to the number showing under my name eventually. I'm still having a problem understanding how that number stayed at 74 on 4 consecutive posts recently. Even today, my total shows an increase of one. Where did the other 3 go?

I just noticed on this thread alone that 3 of my posts show a total of 76!!

[WreckWriter]

Do a search on a post you made a month ago, go look at it. Post count shows the same as on a post you made just 5 minutes ago. Status is the same, check a post I made a week ago when I was a regulator, it will show my current status, not what it was when I made the post.

WW

[seahunter]

Right fredk!
It's a nuisance and expensive but I have to keep at least 2 filter sets (that's 2 filter cartridges at $175 each PLUS 2 separators at $49 each Plus new O rings and BU rings) on hand at all times plus a can of oil $225.
I can't go a couple of days without air. It's particularly bad when the compressor breaks down and despite the best preventative maintenance that will happen. The pressures and heat generated are incredible and occasionally something inside just gives up. Recently without warning the third stage exhaust valve simply blew out of the head. We replaced the entire head ($700) and then though it would be good to check the 4th stage because that would be the likely source of a third stage problem (don't ask - there is a logical explanation but would take too long to explain here) and discovered it was ready to blow too. The fourth stage head cost $600 so the total bill with labor came to over $1700.
This is in January when most stores are pretty quiet and daily cash flow is lower but, you have no choice.
At $5 a fill (if you can get it), the compressor will never be paid for. The diver air fills don't cover even the regular maintenance costs. The above off-season expense alone will require 340 fills.

Air fills should be $10 to $15 (the cost of 2 bar drinks). At that rate ($15) to recoup the cost of the compressor and the maintenance will require 150 fills a week every week for 5 years.
Hell of an investment Eh!
Spend $35,000 and you'll get back the money you spent in 5 years. That's assuming $15 per fill, 150 per week every week and no unforeseen expenses. No profit!!

Not complaining - just explaining!!

[Butch103]

We have heard from other shop owners/operators, all with the same complaints re the loss learder of air, but nice to kinda see the numbers.....i would assume different systems different costs, but it does give you some sort of idea as to the costs of running the compressors for the airfills. Would it be more "profitable" ( I use the term very loosly) to fill by volume as opposed to flat rate ??.......More than likely added costs somewhere to do that also.....

[SneakyB'tard]

Are there any stores that just specialize in air and blending?

If there are, does it help or hinder their ability to make profit by being limited to air service only?

[seahunter]

It's been tried (volume charging) but generally it's more trouble than it's worth. To determine the amount of air sold by the tank (kinda' like propane) is a nuisance. We could make a list of different tanks with the price eg. a 63 costs $4.50; 80's are $5.00; 94's are $5.50 and so on. I'm not sure if other store owners would be interested and I'm not sure how the divers would react.
Generally it's accepted that the diver is not paying for the air but for the service i.e. the cost of compressing the air and then the act of filling. Whether I put 63 cf or 102 cf into a tank doesn't really affect my costs.
About 2 years ago we simply decided to eliminate the problem. We do not charge anything for air fills! Certified divers get free fills (max 2 a day - some instructors tried to bring in 10 -12 tanks for their classes! No surprise there!).
Having determined we were never going to make money pumping air, I figured we might as well get some good will and maybe pick up some customers too. Effectively it became an advertising expense. I have to have the compressor running anyway.
Certainly smaller compressors in smaller stores have lower costs but I think it will all come back to the same. They likely have higher maintenance because their compressors work harder plus it takes much longer to fill the bank or diver's tanks.

[seahunter]

Far as I know no one fills tanks only. Some companies (Liquid Air, Camcarb, etc) fill tanks but not just air and not for an end user. The fills from them whether air or some other gas are not cheap.

There are lots of private scuba compressors around the province. If we could get a list of names and addresses we might be able to set something up.

I very much doubt anyone could make a living only filling tanks. Gosh divers complain about a $4 or $5 fill. That's another problem we got rid of with the free fills!

[GTADiver]

I would pay ten bucks a fill if I new it was good air. I have had experiences with bad air and I would not go back to that shop. I now look for a certificate every time I get air.

[Butch103]

Had I known Seahunter I'd have brought my tanks in on Wednesday when I was in.........Oh well......

I knew that it wasn't an original thought that I suggested, just wondered what the comparison might have been......

[TCDiver1]

seahunter once bubbled...
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. I DO NOT want to meet up with a fungi that can thrive at 3000 Psig.

I'm no biologist but don't think mold growth is possible at that pressure.

[seahunter]

Another related topic is the difficulty we have in getting divers to be patient enough to properly fill their tanks so when they get to the dive site, the tank is still full.

Divers are very used to getting their tanks filled in a few minutes and they complain bitterly (and rightly so) when the pressure is 200 to 300 psi less the next day.

To ensure a good fill (minimal loss) it takes 1/2 hour to fill a tank. The heat generated by the initial filling takes a very long time to dissipate and during that time the tank should be topped up regularly as the pressure drops. If you wait for the pressure to drop a lot before topping up, more heat is generated.
Water baths do not help a great deal especially with aluminum tanks. First the water bath is at room temp or higher (sometimes much higher if there's a lot of fills. Stick your hand in the water at G&S on a busy weekend in Toby).

Some stores are in the habit of filling your tank to 3200 or even more so when it cools the pressure is close to 3000. That's not only dangerous but not good for your tank either.
The only solution is to take time.
I've looked at this a lot because we fill a lot of tanks so get more than our fair share of complaints. Particularly so since we stopped overfilling. We tried filling the tanks quickly and then letting them sit with regular top ups. We tried filling them slowly and then letting them sit with regular top ups. It doesn't seem to make a difference. The heat generated is the same I suppose. With a quick fill it gets very hot but then starts to cool down right away. A slow fill if doesn't get as hot but the time to fill PLUS the time to cool is the same as with a quick fill.
A quick fill is harder on tha tank.

The answer unless someone else has some tested ideas, is to allow 1/2 hour for your fill. Fill it slowly (less than 1000psi/minute) and then let it sit with regular top ups (every 5 minutes) for 20 to 30 minutes. Anything less than that and you'll have substantial pressure loss (more than 10%).

If a diver is not prepared to wait that long then he'll have to accept that the tank pressure will drop. On the other hand, if you need every 100 psi of air in your tank to make the dive safely, perhaps you should modify at your dive plan.

[seahunter]

I don't know gedunk but they've found animals living and growing in the deepest parts of the ocean - no light, high pressure and very cold.

The story about the spit in the tank could be an urban myth but it's very old and it's a good shocker so I'll keep telling it.

Tanks have lots of available oxygen, moisture and warmth. Does anyone know if the pressure will prohibit bacterial growth?

[TCDiver1]

seahunter once bubbled...
I don't know gedunk but they've found animals living and growing in the deepest parts of the ocean - no light, high pressure and very cold.

The story about the spit in the tank could be an urban myth but it's very old and it's a good shocker so I'll keep telling it.

Tanks have lots of available oxygen, moisture and warmth. Does anyone know if the pressure will prohibit bacterial growth? Like i said, i'm no biologist but it seems to me the stuff in the deepest part of the ocean probably slowly evolved to survive there. Take mold or fungus that typically lives at atmospheric pressure and subject it to those pressures and i think you would have dead ala pancake mold or fungi.

Just a guess.

[seahunter]

You're spoiling my story!
I seem to recall it happened in Florida. Does that make difference?

[seahunter]

I notice in your signature the caption 'Go Wings'.
Surely you're not referring to the hockey team that was once quite good?
You must mean Buffalo wings which are very popular here too - especially so on the nights when we drink beer and gather to watch the Leafs win!

[GTADiver]

seahunter once bubbled...


The answer unless someone else has some tested ideas, is to allow 1/2 hour for your fill. Fill it slowly (less than 1000psi/minute) and then let it sit with regular top ups (every 5 minutes) for 20 to 30 minutes. Anything less than that and you'll have substantial pressure loss (more than 10%).



For breathing air most cylinder manufacturers recommend a fill rate of 300-600psi/min. I get scared when I see them filled in ten seconds.

[Butch103]

You could be referring to one of my posts...doesn't seem to matter in this shop if you take it as you wait or leave it for 48 hrs....which they really don't like you to do..........anyway enough ragging onthe LDSs............

[sparky30]

I think hot fills are a fact of life at most dive stores...
I have not found one where they can keep up with demand during a summer weekend.... If you want your tanks filled while you wait and you have 10 people with two tanks each in front of you, you will most likely end up with a hot fill.. The big tub of cold water will minimize the effect, but not by much.. All the more reason to drop your tank off a few days ahead of time.. so they can top it off and there is no rushing..

[seahunter]

If you come into a LDS on Thursday or Friday night or on Saturday morning it could be a bit of a wait. We can fill 4 tanks at a time and can control the fill rate of each individually so it shouldn't be too bad but, you're right spark, Friday night in July can be crazy.

Most LDS including us don't like tanks left for fills. Strictly speaking they must be tagged for service since they are our responsibility while in the store. More than once a customer has left a tank and then not picked it up for several days or even weeks!! When one goes missing (not tagged!) it's a real problem. The owner has no tag, we have no tank - who's at fault? We should have tagged it and given him a service number. Without that we have no responsibility but... at our store I hate to disappoint anyone so I've actually given the customer a new tank based on his word that he did bring it in AND didn't already pick it up. Now you see why we don't want tanks left for fills. The same applies at other stores. If you leave the tank, be certain to get a receipt. The store does not have to give you anything without one.

Ther answer is to bring your tank in during the slower periods. Weekdays anytime, Thurs, Fri, Sat or Sun midday. It may not be the most convenient but I suppose it not a lot different that lining up at a ski lift or golf course on a Saturday morning. For sure it's not fair to blame the owner of the LDS.

Let me suggest that most tanks coming in for fills are at 1000 psi or more. Therefore losing 200 to 300 psi from a regular fill is really more a problem in the divers mind than in practice. However, I too would be irritated if I thought I was paying for 3000 psi and didn't get it. Maybe a change of thought is in order. As I said earlier, you're not paying for the air in the tanks - you're paying for the compression and delivery of the air. Since 2500 is as good as 3000 for most dives, reguler fills are not as big a deal as they're made out to be. If you can accept that idea great. If not and you insist on 3000 psi, you may have to line up.

We get very few divers complaining about the time needed to get a good fill. Perhaps because we don't charge for air fills and also the pro shop is interesting.

[Butch103]

So true....I rarely use all the gas in the tank. When I do it is because I have done a second dive on the tank. ( usually to rehook a dock line, quil check for something etc)...I always plan to end a dive at worse case 500#, but usually hit the boat or shore with 1000# +...My own personal safety facture........:)

[seahunter]

Now that's a good diver!!

I just completed an Equipment Course and we discussed the old 'J and R' valves with reserves. I asked the class how we knew in the early days that our buddy was an experienced diver. The answer is that an experienced diver in the 60's regularly checked his reserve lever to ensure it had not been pulled down accidentally - that it was still up and ready for use.

One thing that has not changed in scuba is that you must not run out of air!! Even bad air is better than no air! Sort of like bad breath is better than no breath!
I don't want to get off topic but even all the current training in handling out-of-air emergencies won't save a diver who runs out of air.