Cave Fills on LP tanks

[BRT]

Im not sure what the actual designations are now days but at one time something about a 3500 psi tank required a different dinn valve than <3500. I probably don't have that right but it is vaguely in my mind of being a catagory change at 3500. The point was really " 60 psi changes the world view" Kind of like a motorcycle race a 199cc is the 200 class but a 201 is in the 250 class. And like bikes you buy them for their class size , not actual size which making comparisons often confusing.
again its like getting a oms 121 tank and it is actually a 125.

It may be the line where 232 or 234 bar is. one is under and the other is over.

There is a category change at 3500 but that doesn't make 3442 low pressure. It is a yoke vs din thing.

 

[PfcAJ]

I also overfill 50s.

Still alive.

 

[LiteHedded]

I also overfill 50s.

Still alive.

livin on borrowed time mate

 

[Caveeagle]

I had a fill station in s fla pump a couple LP72s up to 3300. I gave the guy a little "feedback" just because those are tanks I am much less comfortable with. I keep that at or below 2700.

Honestly, people who keep saying: just get bigger tanks, don't really get it.

I have both LP85s and HP100 available for me to use. At the fill station, they get treated pretty much the same. With a drysuit, salt or he, I prefer the 100s. Otherwise the 85s travel and trim out better with slightly more gas.

When you factor in risk categories for cave or technical dives, this doesn't even make the top 5.

 

[LiteHedded]

I had a fill station in s fla pump a couple LP72s up to 3300. I gave the guy a little "feedback" just because those are tanks I am much less comfortable with. I keep that at or below 2700.

Honestly, people who keep saying: just get bigger tanks, don't really get it.

I have both LP85s and HP100 available for me to use. At the fill station, they get treated pretty much the same. With a drysuit, salt or he, I prefer the 100s. Otherwise the 85s travel and trim out better with slightly more gas.

When you factor in risk categories for cave or technical dives, this doesn't even make the top 5.

as far as I can tell the risk is a big fat zero. one of these tanks has NEVER exploded. not even worth discussing

 

[PfcAJ]

I had a fill station in s fla pump a couple LP72s up to 3300. I gave the guy a little "feedback" just because those are tanks I am much less comfortable with. I keep that at or below 2700.

Honestly, people who keep saying: just get bigger tanks, don't really get it.

I have both LP85s and HP100 available for me to use. At the fill station, they get treated pretty much the same. With a drysuit, salt or he, I prefer the 100s. Otherwise the 85s travel and trim out better with slightly more gas.

When you factor in risk categories for cave or technical dives, this doesn't even make the top 5.

It’s not even on the list at all.

 

[Superlyte27]

OK, fine, so pressures have to be divisible by 3 for rule of thirds, and from @kelemvor's post we see that 3600 is now customary. How long has that been going on? Was it 3300 before? 3000? I don't know -- maybe someone else does -- but I stand by my original assertion that early "cave fills" were made to lower pressures than today's "cave fills." It is based on this that I do not believe that the practice of what are now called "cave fills" can be considered to have a 30 year accident-free history. The actual history is in fact shorter.

I started cave diving in 1996, got certified in 1997. 3600 was very common before that.

 

[Charles2]

Agree there are other factors involved tat what i understand it is in the safety factor of hte tanks. the US uses a factor of 4 other nations use 3 or 2.5 to determine working pressure. NOt that this is 100% true if an LP tank was designated under a factor of 2.5 its working pressure would be 3840 and not 2400 psi wth a factor of 3 it wold be 3200 and not 2400.

A few questions:
1. What does factor of safety mean? Is it equal to burst pressure / working pressure?
2. If equal to burst / working, does that mean that the burst pressure of a 3AA-2400 is 9600 psi? Does an HP-100 with a working pressure of 3442 psi have a burst pressure of 13,768 psi?
3. Where did you get this information? Or is this just anecdotal 'tribal knowledge'?
Thanks

 

[BRT]

A few questions:
1. What does factor of safety mean? Is it equal to burst pressure / working pressure?
2. If equal to burst / working, does that mean that the burst pressure of a 3AA-2400 is 9600 psi? Does an HP-100 with a working pressure of 3442 psi have a burst pressure of 13,768 psi?
3. Where did you get this information? Or is this just anecdotal 'tribal knowledge'?
Thanks

8400# on one that failed viz due to corrosion.
Aluminum tank, also failed viz, similar results

 

[JohnnyC]

8400# on one that failed viz due to corrosion.
Aluminum tank, also failed viz, similar results

Wicked dude! That's awesome!