Cave Fills on LP tanks

[BRT]

Wicked dude! That's awesome!

Good to remember that these were defective tanks that could not be filled because they had failed visual inspection due to corrosion and were not safe.

 

[kotik]

Good to remember that these were defective tanks that could not be filled because they had failed visual inspection due to corrosion and were not safe.

And that the pressure needed to do it is beyond what any dive shop compressor on the planet is capable of. Definitely an awesome video though--

 

[NAM001]

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

I knew it was something, thanks for the clarification.

 

[NAM001]

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

This happens through testing of the tank. Apparently through distructive testing the burst presssure is determined. It is possibly the lowest pressure burst of perhaps 100 tanks tested. that becocmes part of the product information. Now the various nations safety groups adapt a safety factor to determine what service such a tank can be used. the USA uses a consumer safety factor of 4. from that the working pressure is assigned as burst / safety factor. Europe may use 3 or is some places 2.5 as their national standard. Aspects I do not know about is . It the working pressure teh max assigned pressure. Is this destructive testing done after say 10,000 cycles to hydro pressure or half calculated burst pressure, etc. So a tank same as eh us tank was working pressure rated for germany may be different than the rating inthe US. That is one reason the DOT stamp is required onthe tank. That marking identifies the standards including the safety factor infvolvedfor the working spics. Their may also be other things that lower the pressure from that calculated from the burst testing. You mentioned the 3442 tanks their actual burst pressure listed working pressure may be igher but the reduction to 3442 may be a marketing tool. marking such a lower pressure dies not violate the safety factor based working pressure. The safety factor issue was supposedly one of the problems with shifting to an international marking system. all these nation's would have to agree with a working pressure under a common standard. Those that fill international marked tanks would hve to chime in there. I dont have any so i anm not up on them.

At this point i have to say this is tribal knowlege because i don't have the ambition to look it up again

 

[lv2dive]

Count me in (overfilling LP50's) for the hat trick!

I also overfill 50s.

Still alive.

 

[67macoshark]

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.

Why are you less comfortable with the 72's? They are built to the same 3AA standard. Is it just the age of the tanks?

 

[Caveeagle]

Why are you less comfortable with the 72's? They are built to the same 3AA standard. Is it just the age of the tanks?

There are a few reasons I am more conservative with My LP72 tanks.

-they are older tanks that have changed hands several times (still passed hyd/VIP)
-you see more of these tanks failing Hydro vs other steel tanks. (From discussions with a Hydro tech I know, as well as a shop owner)
-they are obviously a lighter weight tank than other steel tanks. They get real floaty when below 1500psi
-some came with vinyl inner liners, and were tumbled a lot to remove it
-tribal knowledge: even people who are ok with "strong cave fills" tend to be more careful with the 72s.

I still think they are great tanks. I own 6 of them. For short single tank dives, even with just the 10% overfill. You get same gas as an AL80, and they are much better to dive. I will also use them for sidemount diving when I just don't need to bring as much gas along.

 

[kensuf]

overfillin lp50s here checking in.

have not exploded yet

I still have 6 sets of double 104s in my garage that haven't blown up since yesterday. Ditto for the sidemount 85's, 95's, and 104's. Plus that 72 of oxygen. Damn, someone get me a lottery ticket.

 

[Compressor]

Amazing thread. I've read all 19 pages so far and basically learned that some fill their above stated limits and some don't.

 

[PfcAJ]

Why are you less comfortable with the 72's? They are built to the same 3AA standard. Is it just the age of the tanks?

I have no qualms with 3000 in my 72s.