BSAC avoids annual VIP

[NAM001]

Would you mind providing your records from your survey of shops to determine their lack of pit picks and record keeping? And just how big was your survey sample to be able to state "the majority of cylinders are not getting properly inspected"?

Just curious....
(and a little tired and a little hangry today)

and then what you are going to match it with YOUR records of YOUR survey to debate the issue. TROLL REQUEST

 

[BRT]

its measured down there or maybe its greater than -100 instead of -200 ... Either way you can purge the atmosphere humidity in the tank when putting on the valve by a couple of fill and vents.

just checked its lower than -100 not -200. .02% rh at 70F is right at -100 dewpoint I want to say the min for some filters components is -50 higher than that thngs like the monoxicon and carbon is not going to function right. so high pressure on the back pressure reg fo the moisture separater adn a good desicant is critical to get that.

OK, There may be some way to get it below -100 dew point. I don't believe any scuba compressor system does.

 

[NAM001]

OK, There may be some way to get it below -100 dew point. I don't believe any scuba compressor system does.

Once again as i understand it the -100 is the dewpoint when it leaves the desicant. a major factor to get that is to have the desicant not do the majority of the water removal. so if you have a say 2700 back pressure on your compressor just after the moisture separator, you will go a long way to gettng that close to most the time -80 or better on the final. another thing that helps greatly is a cooler after the final stage before teh consensation trap/ moisture separator to get even more out of the line before the desicant. there is a good write up on it on foxturd.com regarding compressor filtering systems and getting efficiency. I have one compessor that is a rix 6 and also a bauer 6/min compressor. I have yet to build it but the plan is to put about 50 ft of coiled line in a bucket to further cool the air prior to getting to the separator. a back pressure reg after teh filter stacks will max the dwell time in the filters also. that will also add to the effectivness of water removal because of additional time to dry with longer dwell times.

 

[rjack321]

the majority of cylindars are not getting properly inspected as it is. You ar ehard pressed to fnd a shop that has pit picks let alone a record of inspections. The reality is do a bogus inspection every year or do a bogus inspection every 2-3-4-5 years.

Where's this "fact" coming from?
My inspection tools aren't exactly front and center in my garage but I do have them. And I rarely have to break out my pit picks or gauge - because pitting in my cylinders is exceptionally rare. When I do have a pit its almost always on the outside under the SS stage bottle clamp so highly visible and it doesnt take a rocket scientist to estimate how deep it is.
(BTW there are actually errors in the PSI materials on maximum pit depth. Their numbers are all based on AL3000 cylinders and do not account for AL2015 cylinders which have a much thinner wall thickness. While Al14s havent been made in a few years, even the teachers make mistakes.)

 

[chrisch]

Asking as potentially of interest, not critiquing:
So, i.e. divers driving over from the continent on holiday need not bother bringing any of their own scuba or diluent tanks (tested appropriately wherever they are from) as for sure, nobody will fill them?

The decision to fill or refuse is the discretion of the dive shop. If you have your tanks hydro tested anywhere in the EU you should get a certificate from the testing body. Under EU law it is illegal to discriminate against member states by not recognising their certification procedures. So now you have a viewpoint with which to argue with the dive shop that says no.

However the safety of the person filling the tank is his/her responsibility and they can refuse to fill a tank and effectively not give you a valid reason. Even if they are wrong they have the final say and if they say no there is no mechanism to get your tank filled.

My honest opinion is that if the tank has recently been tested and stamped you would get an air fill most (but not all) places. Most shops would accept that your tank is OK by the standards of it's country. However nitrox or diluent would be a different matter. Without a valid O2 sticker virtually no shop anywhere will fill anything other than air. You can argue all you like (I have) but the answer is no. (Some shops even refuse any other shop's sticker - unless they cleaned [sorry "cleaned"] it no fill)

I find it all stupid, not least because the fire risk is the valve and not the tank and the sticker is on the tank. Also if the tank has only had one or two fills (like a diluent tank or a bailout tank) how on earth can it be contaminated? Oh and yes - you need an O2 sticker (and routine "cleaning" for a tank that is dedicated to pure O2 as well.

 

[NAM001]

Where's this "fact" coming from?
My inspection tools aren't exactly front and center in my garage but I do have them. And I rarely have to break out my pit picks or gauge - because pitting in my cylinders is exceptionally rare. When I do have a pit its almost always on the outside under the SS stage bottle clamp so highly visible and it doesnt take a rocket scientist to estimate how deep it is.
(BTW there are actually errors in the PSI materials on maximum pit depth. Their numbers are all based on AL3000 cylinders and do not account for AL2015 cylinders which have a much thinner wall thickness. While Al14s havent been made in a few years, even the teachers make mistakes.)

By your comment (regarding your garage) I assume you are talking about your tanks, and not the run of the mill tanks the public takes to a shop for a vis. I have not yet found any shop that takes more than 5 minutes or so to do a vis inspection. seldom find a shop that does not call a valve removal look inside dump the dust out and replace a valve a vis. occasonally i find shops that will remove old stickers. occasionally i find a shop that removes a tank boot to check for pitting or rusting. most shops the attitude is 6061's have no problems. less than half the time the valve o-ring is replaced. I took my tanks in years ago and painted a print bridge from the valve of the tank. the paint/ nail polish was not broke and a new sticker was on the tank. Other divers have experienced the same. Lax vis procedures are not uncommon. what is uncommon is that you get your tank back and you get a report (verbal or other) of what was found. I speek a lot to divers that travel. on cruise ships etc.. so i have some what of a mental collection of how things get done across the country. Generally what I hear is that again valves are removed to see if you had any water or oil in the tank from bad fills. If that is good it gets a sticker. I have seen tanks with prop cuts in them and they have a sticker. It is not hard to surmise that the degree of thoroughness is lacking. Also that if using PSI as the standard for measuring a degree of competantcy then is is lacking very much across the board. Just to cover teh base. I seldom get to talk to cave divers to see how tings are done in their area. Most of them inspect their own and also do their own cleaning. Many do not have vis stickers on their tanks at all. But over all when you look at the cave community it is a rather small % of the divers out there. When you talk about your tanks and where you find your problems, I have to say my tanks are the same way. no one uses them but my wife and me. the only chips or gouges are in the paint from hydro stamps. I would estimate that of the tanks i see,,,, at the half a dozen sites i can locally can go to,,,,, over half have several years of stickers on them. I think this is the sae type of thing where i take in my lp tanks for a fill adn come home with 3200 in them because they never read the tank to see full was 2640 with the +.... This i find to be area dependant some what, ask the tank monkey about the + on a tank. many have no clue they just fill to 3200 so they cool to 3000 and the job is done.

Because of those observations and comments form so many others as well as mine from allover the country I take the position that thorough vis's are not done. What causes that attitude in shops I dont know. Perhas this is just a small mom and pop shop thing. It certainly is not prevalant is any shop that deals with any one tech. I can only guess that the shop policy (right or wrong) is to not deal with tanks over 20 yo. As AL's go there is nothing but 6061's that are dhop elegible to be filled and they have no machine to look for cracks because of that of that same policy. I have had tank monkeys look for tank date (oroiginal hydro) and ignore everything else like working pressure.

 

[TrimixToo]

When I put my valve on i presureize it to 1500 adn drain refill to 1500 and drain. any humidity in it from atmosphere when the valve is put on is reduced everytime you fill with dry air. if you had atmospheric air with rh60% and you fill to 1500 dnavent to 100 you now have 6% RH at 1 ATM do it again and you have .6% atmfill it again and it dont matter anymore because the fill to 30 will tru to make it around .03% rh at 1atm ,,,,,,,,,,,,,,,,, that is a low dew point probably well under -200f. The only thing that can mess it up is a wet fill from bad filtering.

Unless you are getting air from someone who fractionally distills it from the atmosphere, I rather doubt that you can find any with a -200F dew point. My compressor's DP is -70F on the latest test report.

 

[BRT]

Once again as i understand it the -100 is the dewpoint when it leaves the desicant. a major factor to get that is to have the desicant not do the majority of the water removal. so if you have a say 2700 back pressure on your compressor just after the moisture separator, you will go a long way to gettng that close to most the time -80 or better on the final. another thing that helps greatly is a cooler after the final stage before teh consensation trap/ moisture separator to get even more out of the line before the desicant. there is a good write up on it on foxturd.com regarding compressor filtering systems and getting efficiency. I have one compessor that is a rix 6 and also a bauer 6/min compressor. I have yet to build it but the plan is to put about 50 ft of coiled line in a bucket to further cool the air prior to getting to the separator. a back pressure reg after teh filter stacks will max the dwell time in the filters also. that will also add to the effectivness of water removal because of additional time to dry with longer dwell times.

I have a refrigerated cooler on the output from my compressor but I do not believe my air is that dry.

 

[Diving Dubai]

So a modern day steel tank, galvanized or zinc coated, is subject to the same testing procedures as those 1970 tanks, still in use today, that flash rust in the blink of an eye. Does that help clarify how we arrived at the current state of inspection practice and controversy

I can relate to this. In teh 90's when I was in the aerospace business, we were trying to qualify water based primers.

Anodized Ali and Cad plated Steel samples were all painted and placed into a small environmental test chamber for 28 days for accelerated enviro testing. They had a (calibrated) score made through the primer and electro treatment before being put in. The test alternated them being dipped in water and left in warm humid air 24/7.

They were 4mm plate (5/32) and they would be destroyed in 28 days the worst (on the primers that failed) would look litterially like paper table decorations - all losing over 50% of their material thickness.

So in the real world, unless you remove all old cylinders from circulation you have to match inspection frequencies to meet teh most vulnerable.

Even those cylinders with galvanic coatings (and anodizing for Ali) aren't impervious. The plating is easily damaged even on the inside by carelessness, and given the right conditions, that tank will corrode. The effects are more dramatic on steel because of their thinner wall thickness.

 

[BRT]

I can relate to this. In teh 90's when I was in the aerospace business, we were trying to qualify water based primers.

Anodized Ali and Cad plated Steel samples were all painted and placed into a small environmental test chamber for 28 days for accelerated enviro testing. They had a (calibrated) score made through the primer and electro treatment before being put in. The test alternated them being dipped in water and left in warm humid air 24/7.

They were 4mm plate (5/32) and they would be destroyed in 28 days the worst (on the primers that failed) would look litterially like paper table decorations - all losing over 50% of their material thickness.

So in the real world, unless you remove all old cylinders from circulation you have to match inspection frequencies to meet teh most vulnerable.

Even those cylinders with galvanic coatings (and anodizing for Ali) aren't impervious. The plating is easily damaged even on the inside by carelessness, and given the right conditions, that tank will corrode. The effects are more dramatic on steel because of their thinner wall thickness.

People seem to think that steel cylinders are coated or galvanized on the inside. With the exception of some old steel 72's I don't believe this is true.