Visuals on all emptied tanks?

[cat]

Biology, explained well enough, is chemistry.
Chemistry, explained well enough, is physics.
Physics, explained well enough, is mathematics.

... and no-one seems to be able to explain mathematics well enough

 

[Doppler]

cat once bubbled...
Biology, explained well enough, is chemistry.
Chemistry, explained well enough, is physics.
Physics, explained well enough, is mathematics.

... and no-one seems to be able to explain mathematics well enough

Run away with me Cat.... :wacko:

 

[pufferfish]

Thanks professor Cat and Doppler for your chemisty and physics classes there. It is nice to have some experts around for us jack of all trades, master of none types.

Now Cat you have a serious problem if you are doing fills downwind of that Bowater plant. They are number two in the country for air pollution releases and you might have a serious problem taking some of those nasties to depth. Hydrogen sulphide is the one that gives that sweet smell right? I guess that is the one time the PADI tank taste and smell test might actually work!

Have you been up to the Rossport Inn yet for dinner? Awesome food and real nice atmosphere as the Inn was built in the late 1800's. Down a little further the Kinniwabi Pines restaurant in Wawa is real nice too. And if you want to try your hand at kayaking the Pukaskwa coast I'd highly recommend David Wells op in Wawa, Naturally Superior Adventures. Stunning scenery there.


Ok back to the tank fill pressure thread.

 

[cat]

The list of chemicals that can be scented on the air around many pulp mills (Cornwall's is really horrible, IMO) is long and varied and includes things like mercaptans. Definitely puts me off eating on the rare days that wind blows in the wrong direction. H2S, the stench (I wouldn't call it a sweet smell, pufferfish) of which I commonly associate with black anoxic mud and Alberta gas wells, oxidizes fairly readily to sulfur oxides (which still stink). Fortunately, the days where the wind blows from the mill to the town are very infrequent. Haven't had a stinky tank yet, nor heard of one. Suspect I won't - the guys who fill tanks and change the filters at Wally's (including Wally and his son) breathe more of it than I ever do - enlightenened self-interest is a good thing.

I have not had time to do much non-diving related travelling - it's busy season for us aquatics types (thought I counted as a JOAT too ) Still managing to take in a decent dose of stunning scenery - there's rather a lot of it up here, so it's unavoidable.

Doppler: What? And leave all this stunning scenery?

 

[Doppler]

cat once bubbled...
SNIPPED


Doppler: What? And leave all this stunning scenery?

Scenery... you can't see it for all those Rocks and Trees. (Heard the Rocks and Trees song, at Mariposa this last weekend. Do you know that one??)

Rossport is the launching point for our Gunilda dives and the Rossport Inn has quite the rep. with our crew! Strange and eccentric owner!

Tank fills!!! Puffer, what would you suggest one does for a portable compressor? Any suggestions regarding filter set up or ways to manage the risk of contamination while on Expedition... to places like Rossport where there is no "local" air station.

 

[ScubaScott]

...... wow. I'm confused......

SS

 

[Doppler]

I must say that as much fun as we get poking holes in each other's posts... Scar Tissue, really!!! SeaHunter is correct on several scores when it comes to the "Short Fill" issue.... First of all, it's not a big deal. A couple of hundred psi or a few BAR shouldn't make much of a difference to your dive plan. Secondly, there's not much that one can do to change it... "Yer cannea defy the laws o' physics, Captain!"

Of course, the CGA regs do allow for a percentage overfill to compensate for temperature / pressure drop, but even so, you gotta be more flexible in your expectations for a fill guys.

Now if it were liquid air the thermal effects would be less... HAHAHAHA

Doppler

 

[Bubble Boy]

seahunter once bubbled...

By law I can fill a tank to it's stamped pressure only. If filled properly, you get a full tank. If a dive store owner is prepared to break that law (assuming he evens knows about it!), what other laws do you suppose he would break to make money??

The main thing to do is follow the manufactures specifications and fill at a rate not exceeding 300-600 psi/min. CSA B-340 clearly states that the service pressure shall not be exceeded when the container temperature is 15 degrees C and 125% service pressure when the container is 55 degrees C.

I must agree with you SeaHunter that 200 psi should not make a difference to some one that plans their dive and dives their plan.

 

[pufferfish]

Doppler once bubbled...
I must say that as much fun as we get poking holes in each other's posts... Scar Tissue, really!!! SeaHunter is correct on several scores when it comes to the "Short Fill" issue.... First of all, it's not a big deal. A couple of hundred psi or a few BAR shouldn't make much of a difference to your dive plan. Secondly, there's not much that one can do to change it... "Yer cannea defy the laws o' physics, Jim!"

Of course, the CGA regs do allow for a percentage overfill to compensate for temperature / pressure drop, but even so, you gotta be more flexible in your expectations for a fill guys.

Now if it were liquid air the thermal effects would be less... HAHAHAHA
Doppler

I would have to agree with you Doppler that Seahunter was bang on with respect to his commentary on tank fills. Had he just left off that point #7 it would have not set off my fact or fiction radar,..ha,ha. Now Cat if Seahunter fills a tank at 20 C and takes the appropriate time say of ten minutes to do a dry fill and fill to 3000 psi, what would the pressure drop be after letting the tank cool back to 20 C. And after a fill done in five minutes? Probably no less than 2800 psi right? Now I get it free fills, free coffee, and a forced ten minute respite in the shop to look at stuff I need. Very smart indeed

So Dopp have you dove the Gunilda? Wow 240 feet in the mother of all fresh water lakes no less. You are right about the owner of the Rossport Inn who I believe is an ex USAF pilot. He has all kinds of stories to keep guests entertained. I can't remember how he met his wife but that was a neat story too. I do recall when one goes to register at the desk there is a large newspaper article on the wall to the left about the Gunilda and a diver death on it. I guess this is just to warn divers before they take the plunge on her.

Remembering I am not an expert on compressors but do consider myself quite well informed now (in a large part thanks to SH and self-interest) I would say your concern about air quality using a portable compressor (?gas) would be the number one risk management issue on such an expedition. The reason I say this is I assume divers heading down on the Gunilda are the cream of the crop and therefore have the best equipment and many years of deep mixed gas experience before attempting such a dive. Please don't tell me that deep diving has or is becoming like climbing Mt. Everest where anyone with the desire and $$ can be guided down to the Gunilda.

Again as I had mentioned to you before it always amazed me that tech divers obsess about this configuration, that training agency, and that hose length but not a peep about their air quality. In the US one hears a lot more about oxygen compatible air (OCA) and debates about not only the amount of particulates or hydrocarbons in the air but the size of those particulates. Here in Ontario we debate (we being recreational divers mainly) whether using the OUC unaccredited lab once or twice a year is a prudent way to manage contaminant risk. And the worst offenders of all for either denial, arrogance, or ignorance seem to be the tech shops in Kingston, Mallorytown, and St. Catharines. These tech guys (on the bleeding edge of dive info) who really should be up to speed on the reasons why OCA air is important at depth (effective concentration of contaminants at 7 atm) continue to mix uncertified OUC air to a 1985 standard with your 'medical' grade helium and oxygen. Sounds to me like the, "I'll have a diet coke with the big mac and fries syndrome"! That OUC air is what you got to worry about and using medical grade He won't mitigate the risk of OUC air at 7 atm.

Ok I will get back to your question but that topic hit a raw nerve with me,.. mixed gas stations using OUC air,...kind of like when you mention Maxxam to Seahunter where unpredicatable things get said

Assuming I was going to dive the Gunilda (only in my dreams) I would think of all the risks I might encounter and can control. Pretty much everything like equipment, training, pre dive sleep, diet, psychological prep is all in my control. If I screw up here I am the one that will become a statistic. Now the one huge risk I cannot control and might not know much about is my air source. Someone else likely supplies a portable compressor which I have no idea about the quality, when the last filter and oil changes were done, etc. If you search under 'compressors' on this site as I did and read some of the threads from experts on portable compressor and filtration the number of issues to consider with regard to air quality is huge. Types of filters, intake placement issues, filter order issues (guys putting the dessicant after the charcoal), back valve issues, oil issues, the list is huge. If you don't own the compressor and maintain it I would hazard to guess the portable compressor is your greatest concern re risk management.

So what to do? I would simply tell the guy setting up the compressor to get up there a few days before and set up. I would then arrive at least a day before ideally more (to let the HPA axis settle after the long drive) and have a sample bottle from either Seatech or (shhh) Maxxam on hand. Run the compressor at least a half hour and then fill the bottle over twenty minutes. Call Purolator to the Rossport Inn to pick up the bottle and have them rush the sample to Halifax or Toronto. The lab will do a sample on 6, 24, or 48 hr notice for a fee (see www.seatech.ns.ca). Don't worry about the $$ as this is the one risk factor worth spending the money on to reduce the contaminant risk to its lowest level when at 8 atm. The next day you get the result back on the compressor setup exactly where you intend to use it. That way if there is some strange gas drifting in from Bowater at Thunder Bay you might know about it. Also you don't have to worry about all those issues you can't possibly check like oils, filters, backvalves, etc. You will have a air cert done one day before you dive that reflects that compressor setup one day before you dive. That way you don't have to worry about the typical yada yada, "oh yah I changed those filters last week or I dove the air last week and it was fine, trust me."

On the day of the dive I would inspect the wind direction and where my exhaust and intake are. Forest fires which are very common up that way with smoke in the air would be an absolute contraindication to a deep dive. Likely lots of CO2 and CO if there is smoke in the air.

As a final check on my tanks to be used on the day of the dive I would use my portable CO monitor and assess the dewpoint as well. For that type of dive (deep and cold) I would accept a CO level of zero and the dew point should be very low (<-60F). If either of those start to creep up during the expedition I would be suspect of a filter problem. One can use serial CO and dewpoint levels over days, weeks, or months to detect possible early filter degradation by moisture. A CO level that goes from zero to five ppm or a dewpoint that rises quickly assuming no new intake sources or CO or humidity might be your 'smoking gun' to look a little closer at that compressor and how it is being operated. Remember in the six months between air certs as is required by the Ministry of Labour a lot can happen to a compressor especially when it is working overtime during the hot busy summer months. The serial CO/dewpoint technique may allow the diver an interim assessment of fill station quality.

The last issue you will see in some of the compressor posts is one of particulate matter quantity and size in the fill. I would only accept an oil and particulate level of <.1 mg/m3 for a deep dive. As far as particulate size this is open to debate although there is a lot of recent medical research on particulate matter (PM) less than 2.5 microns causing cardiorespiratory problems in susceptible people. Theories include cytokine production, changes in blood clotting componenents, or direct cardiac toxic effects. Personally I think this is where the answer to pulmonary edema of diving might lie or the 'sensitivity' to it in some individuals. If you are getting your air locally in Rossport PM concentrations are not an issue although I would check the MOE air quality index for Tbay as it has had some higher levels when wind conditions are right from the States. As for filters I would insist on some sort of hyperfilter at least down to the US Navy standard of 5 microns (the smaller the particles less than 10 microns the deeper they penetrate the respiratory tree). ANDI 1994 specifies < 2 microns which is even better but adds additional cost to the fills. Lawrence Factor (www.lawrence-factor.com) I think sells a portable hyperfilter you can attach to the fill whip. In anycase for those deep dives with higher effective concentrations I would go for a minimum of 5 micron in the fill.

So there you have it. I am not a deep diver but have been to 20,000 ft above sea level and experienced mild AMS. Did the climb without much knowledge of AMS and after reading about the physiology behind this a few years later I realized lots of dumb things were done on my part. You know the saying of bold vs. old! Would do things very differently now. As you know 'knowledge comes from books, but wisdom come from life' but sometimes wisdom does come from doing dumb things and then realizing in hindsight boy I am lucky to be talking about this.

Hope this long post (as bad as SH I know) helps or at least gives you some things to think about to help reduce that large blind spot in risk that really does exist for tech divers called air contamination. As I said I am no expert but these would be issues to consider and an approach to the problem. Looking forward to hearing some ideas too from JimmyB :mean:

 

[Jimmy B]

I still think the best approach would be to lobby the OUC to move to your perferred testing station. Then everyone would be in the loop and OUC would again start to grow some teeth. Instead of reinventing the wheel why don't we re-engineer what we have.

JB

Just because Puffer asked.