HP100 vs LP95 steel tanks

[tech3324]

I would look at a cylinder table, maybe like this one Scuba Cylinder Specification Chart from Huron Scuba, Ann Arbor Michigan and compare the buoyancy characteristics of the HP and LP tanks you are considering, might have an effect on your weighting.

Also, my regulators are older yoke mount and only rated for 3000psi service, so I probably wouldn't fill an HP tank to over 3000psi.

 

[Lenaxia]

Trim really shouldn't be an issue with single tanks, because you have the option of moving them up and down in the cambands. The only time it might really be a problem is with either VERY long tanks (like the 120s) or VERY short ones (like the HP80s). Anything else is going to be adjustable enough.

I find the HP100s and LP95s balance almost exactly the same, but the 100s are lighter, and I appreciate that when I'm hauling tanks on and off boats, or in and out of the truck. But we ended up doubling up our 100s, so I use the 95s as single tanks. (I don't like them as doubles AT ALL!)

Actually, my issue with LP95's wasn't a pitch issue but a roll issue. I found the LP95's tend to take worse to swimming sideways than the HP100's. By extension, any position other than superman horizontal was less stable with an LP95.

It wasn't a huge difference and if I have to dive an LP95 then I would still be fine. However there is a subtle difference to how the two tanks feel and so if I were given a choice I'd choose an HP100.

 

[elmer fudd]

If you're going to get LP95's, you may as well get HP119's instead. They have almost identical weight and dimensions, but the later is rated for 24 more cf of air. The only significant difference between the two is that one is rated for 2640 psi and the other for 3442 psi. I really can't see any reason why I'd want my tanks rated at a lower pressure. You can still fill an HP119 to 2640 if you want and dive with only 95 feet of air, but you can also have it filled to 3442 without being part of the Florida cave diving community.

 

[DA Aquamaster]

A couple more thoughts:

The Worthington X8-119 is basically a higher pressure rated LP 95 (in terms of weight and dimensions - not so much in terms of metalurgy).

But, for an extra pound and 1.5" of lenght, you can get an X8-130 and pick up another 7 cu ft of gas. (an X8-119 actually holds 123 cu ft at 3442 psi)

And,

Most yokes using a 9/16" yoke screw will tolerate pressures up to 4000 psi without stretching regardless of the stamped pressure. And I am not aware of any current yokes that won't handle the 3442 psi pressure of the current "high pressure" tanks available in the US. Thus the convertible DIN/K valve intended for 3442 psi service pressures. So...if the reg itself is compatible with 3500 psi pressures (if a DIN version is available) then I would not stop at 3000 psi fills in a 3442 psi tank just because you have a yoke reg.

 

[tech3324]

So...if the reg itself is compatible with 3500 psi pressures (if a DIN version is available) then I would not stop at 3000 psi fills in a 3442 psi tank just because you have a yoke reg.

But on an older reg like my Conshelf it's unclear whether a DIN version was available or not. So my thinking was to go with the pressure stamped on the yoke as a safe maximum.

 

[DA Aquamaster]

A Conshelf 12, 14, or later will do fine at 3442 psi and the yokes are good to go to 3500 psi.

 

[elmer fudd]

A couple more thoughts:

The Worthington X8-119 is basically a higher pressure rated LP 95 (in terms of weight and dimensions - not so much in terms of metalurgy).

But, for an extra pound and 1.5" of lenght, you can get an X8-130 and pick up another 7 cu ft of gas. (an X8-119 actually holds 123 cu ft at 3442 psi)

Good point. I would have bought 130's, but my LDS had new XS 119's for $329. 130's were considerably more.

At similar prices I'd definitely go for the 130's.

 

[spectrum]

Getting fills of 2800 -3000 on a HP cylinder is extreme unless the shop didn't have the capacity to fill to 3442. On a quick insta-fill about the worst I have had is 3250 which puts a ding in the capacity but it's not the end of the world. As mentioned dropping them off for a fill and top-off when cool should deliver perfect fills.

I have not been a big user of LP cylinders but don't count on perfect fills there either. Boyle's law will take a toll on LP cylinders though it's not severe. Consider however that being 100 PSI short on a LP is not too different than being 150 PSI on a HP fill. That begins to level the playing field.

There are shops and regions where it's commonplace to get bodacious fills for LP cylinders. That's an anomaly and if it's available to you then then so be it.

As for feel and trim that's mainly an adjustment deal and a little playing with your configuration will clean that up. However a larger LP cylinder may work better for a toll diver and a stout HP may be the ticket for a shorter person.

Pete

 

[kramynot2000]

But on an older reg like my Conshelf it's unclear whether a DIN version was available or not. So my thinking was to go with the pressure stamped on the yoke as a safe maximum.

I had LP95's and my experience was the same as what was previously described, that sometimes you'll only get a 2400psi fill, especially if your tanks weren't last hydro'd with the +. Then you have one very heavy 80.

I ended up selling the LP95's and now have E8-119's, which are pretty much the same tank but rated to 3442. Also, I use my DIN Conshelf 22's with them and have had no problems.

 

[HFig]

All I use is Faber LP-95s with 3600 psi fills you'll get 130 cu' out of them. I have used worthington HP-130 and found the trim and buoyancy characteristics to be far superior with the Faber's. I'm using them as back mount doubles right now.