BSAC avoids annual VIP

[chrisch]

What people use as "evidence" is the number of reported catastrophic failures.

No-one records details of cylinders failing vis or hydro, so there are no true numbers.

Hence my disgust at teh fight in the UK with the standards, as it's not based on any empirical data

Not true. The number of cylinder failures was a critical part of the reason that the UK did not adopt annual tests. The data shows there was no need to do so.

It is important to remember that the UK is nearly all steel tanks and the US nearly all Alu. The two countries are not the same. Also terrible water and salt ingress like the photos above show that the tanks have been emptied and sea water has got in. This is unforgivable. I hope it is not representative of any divers anywhere.

To the best of my memory nearly all the catastrophic failures in the UK have been pony tanks and water ingress due to breathing dry was the diagnosis in most cases. There is also an issue with the mini tanks used on dSMB and some old fashioned BCs. These do not need a test at all and are frequently subject to water ingress as they are emptied underwater as a routine event.

Perhaps the proposed change of testing should have been to include the mini tanks and to annual test pony bottles only? I can imagine the howls of protest at annual testing diver's little comfort blankets

I have no doubt whatsoever that if there was any logical reason to annual test the UK would adopt it in a heartbeat. Making money from health and safety mythology is what we are good at.

 

[TrimixToo]

I believe that. depending on the brand or type of of desicant you can improve that and increasing dwell time and use of multiple filtering stages can get it below -100.

I have a K14 with three filter towers. The first two are entirely 13X dessicant, the third is about half dessicant. I don't know their volume with the cartridges installed, so I don't know the total dwell time. The PMV on the downstream side of the towers is set at the pressure Bauer recommends. The club's compressor has similar filtration and about the same dew point. I could add refrigeration ahead of the coalescer if I were so inclined, I suppose. Increasing the PMV setting would dry the air more by increasing the dwell time but it's kinder to the compressor to leave it where it is set.

I still think that -200F difficult to achieve.

Also, since it's come up elsewhere in the thread, I will add my belief that the dew point is measured at STP (Standard Temperature and Pressure). It's considerably higher (a smaller negative number) under pressure, IIRC. That said, I never see evidence of condensation in my tanks (rust spotting) even when I dive in the winter, so around here, at least, -70 or so is "dry enough."

 

[Edward3c]

…
So, where’s this bs of “no evidence of increased safety” by inspecting every year come from, I still haven’t got an answer about how they arrived at that conclusion.
...

What people use as "evidence" is the number of reported catastrophic failures.

No-one records details of cylinders failing vis or hydro, so there are no true numbers.

Hence my disgust at teh fight in the UK with the standards, as it's not based on any empirical data

SITA (Scuba Industry Trade Association) gathered the failure rates from the UK test houses:
• Number of tests undertaken (in the thousands),
• Number of failures, type of failure,
• Cylinder age, size, condition, pressure,
• The survey covered a number of years not just the most resent.

The cylinders at most risk are 3Lt and smaller, where the thread might fail.

...
In closing...don't get your frillies in a flutter...this reduced inspection protocol is not going to happen in North America...
...
Warren.

For the U.K. it isn’t a reduction from anything to 2½, 5 years. We’ve had this regime for over 20 years.

 

[BRT]

I have a K14 with three filter towers. The first two are entirely 13X dessicant, the third is about half dessicant. I don't know their volume with the cartridges installed, so I don't know the total dwell time. The PMV on the downstream side of the towers is set at the pressure Bauer recommends. The club's compressor has similar filtration and about the same dew point. I could add refrigeration ahead of the coalescer if I were so inclined, I suppose. Increasing the PMV setting would dry the air more by increasing the dwell time but it's kinder to the compressor to leave it where it is set.

I still think that -200F difficult to achieve.

Also, since it's come up elsewhere in the thread, I will add my belief that the dew point is measured at STP (Standard Temperature and Pressure). It's considerably higher (a smaller negative number) under pressure, IIRC. That said, I never see evidence of condensation in my tanks (rust spotting) even when I dive in the winter, so around here, at least, -70 or so is "dry enough."

You can find an online dew point calculator. -65 isn't low enough for me as I may transport filled tanks well below 20 F.

 

[Bob DBF]

Also terrible water and salt ingress like the photos above show that the tanks have been emptied and sea water has got in. This is unforgivable.

To the best of my memory nearly all the catastrophic failures in the UK have been pony tanks and water ingress due to breathing dry was the diagnosis in most cases.

Seems like the issue is divers ignoring the fact they have breathed the tank all the way down, and refusing to take a look inside. I certainly can tell if I breathe a tank down, not that I do it often, and the next maintenance on my list is to open the tank and insure it stayed dry, anything else is asking for problems. Sounds like a training issue rather than a tank issue.



Bob

 

[chrisch]

Seems like the issue is divers ignoring the fact they have breathed the tank all the way down, and refusing to take a look inside. I certainly can tell if I breath a tank down, not that I do it often, and the next maintainance on my list is to open the tank and insure it stayed dry, anything else is asking for problems. Sounds like a training issue rather than a tank issue.

I was trained to leave some gas in the tank I doubt many divers realise they should inspect a tank if has been emptied in this way. It's something I learned from working in the industry and being a sad dive junkie addicted to forums and not from any diver classes or formal training.

 

[kelemvor]

I was trained to leave some gas in the tank I doubt many divers realise they should inspect a tank if has been emptied in this way. It's something I learned from working in the industry and being a sad dive junkie addicted to forums and not from any diver classes or formal training.

I don't know about other agencies, but any NAUI certified diver knows this. It's on Page 23 in the NAUI Scuba Diver (open water) manual. Probably gets covered in the first day or 2 of class.

 

[boulderjohn]

I was trained to leave some gas in the tank I doubt many divers realise they should inspect a tank if has been emptied in this way. It's something I learned from working in the industry and being a sad dive junkie addicted to forums and not from any diver classes or formal training.

That is part of standard PADI OW instruction.

 

[chrisch]

That is part of standard PADI OW instruction.

I don't know about other agencies, but any NAUI certified diver knows this. It's on Page 23 in the NAUI Scuba Diver (open water) manual. Probably gets covered in the first day or 2 of class.

I guess it is easily forgotten then if it is in OW training.

 

[Stoo]

well I have to take my hat off to BSAC on this one. It appears they have avoided implementing annual VIP's for dive cylinders. Now we just need the US to get rid of them as well and the world will be a better place....

BSAC Takes Stand To Avoid Annual Cylinder Inspections – DeeperBlue.com

I managed a shop in Tobermory in the very early '80s and I seem to recall that VIPs were just becoming a thing at that time. I have no recollection of there being a series of exploding tanks leading up to this, any more than there have been since. I also recall that the "qualifications" for we inspectors were suspect at best. Thankfully, at least that aspect has been improved.