Cave Fills on LP tanks

[Michael Guerrero]

My LP85s are in hydro after 5 straight years of 3600+ fills. I'll post if f I get them back without holes drilled in them.

 

[HalcyonDaze]

Almost two years ago I acquired a set of LP 121s for the price of the hydros. Not being a cave diver and generally being a stickler for going by what the label says, I've only had them overfilled to ~3500 cold twice here in Miami; I'm not sure if the shops gave me cave fills without being requested or if the employee working the compressor assumed they were HP tanks. The first time it was a bit concerning because the valves only have 3000-psi stamped burst disks and, not being familiar with the limits on LP tanks, I was asking a few people that week if I had a couple bombs sitting in my living room. Was nice to have ~170 cf of back gas on my next dives ...

 

[Fruitographer]

I'm diving sidemount and prefer the LP85's over HP100's. I have a spinal injury and that's just to much steel to have thrown on my back and causes a lot of pain. I would rather have 4 smaller tanks that I can maneuver around with than 2 buses strapped to my back. If you ever end up in the caves you'll have to match gas with the person who has the smaller cylinders anyway. So even if you have 104's, if your buddy has 80's you'll only be able to use the equivalent of whet they have anyway. So now you'll basically have huge tanks that you'll only be able to use 80cf from.

 

[Caveeagle]

...So even if you have 104's, if your buddy has 80's you'll only be able to use the equivalent of whet they have anyway. So now you'll basically have huge tanks that you'll only be able to use 80cf from.

The gass matching comment is true as applied to limits to penetration and turn pressure.

However, that BM diver with the "giant busses" will surely be your BFF if you have an OOG situation. That extra capacity is still there if/when you need it.

Biggest issue with diving large capacity tanks is the penalty of drag from tanks and wing inflation.

 

[kelemvor]

My LP85s are in hydro after 5 straight years of 3600+ fills. I'll post if f I get them back without holes drilled in them.

My 108's got their first hydro last year. I was a little nervous because of the overfills. All four came back with the + rating. I guess a little validation goes a long way.

 

[Lobzilla]

The gass matching comment is true as applied to limits to penetration and turn pressure.

However, that BM diver with the "giant busses" will surely be your BFF if you have an OOG situation. That extra capacity is still there if/when you need it.

Biggest issue with diving large capacity tanks is the penalty of drag from tanks and wing inflation.

+1

AL80 doubles (154cuft@3000PSI) and a wet suit got me about as far into the flow of Ginnie as the LP104 busses (312cuft@3600PSI i.e twice the gas) with a drysuit. But if something happens, the big tanks sure give everyone a whole lot more time to sort things out.
Blind, gas sharing exit with the small tanks? No thanks. Unless I am diving with an instructor who reaches 1/6 in his AL80s after I reach 1/3.

 

[PfcAJ]

Biggest issue with diving large capacity tanks is the penalty of drag from tanks and wing inflation.

Helium helps.

 

[PfcAJ]

You're in largo. I'm in st Pete. If yo're really looking for a butt puckering thrill, you can come by my house. I've got a couple pumped up to 4200 in my garage.

Come hang out with my lp95 juiced with oxygen

 

[Fruitographer]

If someone wants to carry around those gigantic things so we have an extra safety buffer I'm all for it. Unless they have them because their SAC rates so bad they need something that big. In that case I don't want to share air with someone who's going to breathe down everything I have before we make it to the exit. I'd rather dive with someone who has smaller tanks and breathes more efficiently. I say improve your SAC rate before going to larger tanks. Once that's good and you still want to have the 104's then go for it.

I'm only 5'6" and 145lbs so a pair of 104's are larger than I am. the amount of drag it would create for me would make the dive miserable. In open water, Ievery time my SAC rate was substantially better than everyone I've dove with. Even if I was kicking and they had a scooter, I would still come up with more gas left in the tank. That changed when I first got in the cave and didn't understand where the flow was. My instructor use the half the gas I did. I'm pretty good now but I've only been in the caves for the last two years so I still have a lot to learn.

 

[kelemvor]

I think you're overestimating the size difference.
A luxfer al80 is 7.25" diameter, 26.1" tall. A worthington LP108 is 8" diameter, 26.5" tall So it's 0.75" larger diameter and 0.4" taller than a standard al80. As far as the size goes, other than the fact that it doesn't fit into tank holders on some boats it's a very minor difference.

Now, the LP108 is 14.5lbs heavier than a standard al80. That's a pretty big difference. I think that the weight is also a boon, as it means I generally do not need to carry much lead (if any at all).