DEMA - Pressed Steel new tanks?

[MikeFerrara]

Genesis once bubbled...

A twinset of HP100s, empty, will have a buoyancy difference from the E130s of one half pound. If you need V-weights for those and not for the E130s then I have to wonder what you're doing, because half a pound isn't enough to make any material difference to anyone I know of.

I don't know for sure about the e-series tanks but the lp tanks are 3-4 pounds more neg (empty) than the the hp tanks. This is per PST and is consistant with the results we get in the water.

As I explained in another post the dealer price list has a set of specs that reads different than the catalog specs. The catalog specs are calculated while the others are measured in salt water and include the valve. Regardless of what the published specs say there is a big buoyancy difference between the lp-104 and the hp-100

 

[Genesis]

that's gone though - at least it does if the new E-tanks are what PST appears to say they are.

Perhaps PST is wrong. Perhaps they're not. But I bet they're not, because they're shipping with the Thermo valves and I suspect they've done their homework on these tanks.

And while Fabers may be an option for fresh water divers, cold-dip (really spray painted on!) galvanizing in salt water is asking to have the tanks rust to the point where they fail a vis. You want hot-dip for salt water steel tanks, and the only place you can get THAT is from PST.

 

[pescador775]

According to Rodales, the PST HP 100 is more negative than the LP 104.

LP 104.....(-)0.7 lbs empty
HP 100.....(-)1.4 lbs empty

http://www.scubadiving.com/gear/27tanktips/stats.shtml

 

[Genesis]

by seven tenths of a pound!

This is material? I don't think so. Even if you have a twinset, its a 1.5lb difference.

If that's a big deal to you one way or another, me thinks you doth protest too much!

The LENGTH issues may be real for some people - that I freely admit...

 

[MikeFerrara]

pescador775 once bubbled...
According to Rodales, the PST HP 100 is more negative than the LP 104.

LP 104.....(-)0.7 lbs empty
HP 100.....(-)1.4 lbs empty

http://www.scubadiving.com/gear/27tanktips/stats.shtml

It sure can be hard to get a point accross around here sometimes. Their numbers come from the catalog which is calculated from design criteria PER PST My numbers come from the dealer price list and are actual measurements. Not to mention the fact that I have made hundreds of dives in both tanks and I can tell you that the lp 104 is 3 - 4 pounds more negative than the hp 100. In fact I originally used hp 100's because the published buoyancy numbers were better. They were wrong and I switched to lp 100's. As always Rodales doesn't know crap.

All the info I have posted on PST tanks has come directly from PST and, of course, personal experience which bear the other out.
When I get back to the shop I'll post the numbers from the PST price list.

 

[Genesis]

then I would be dangerously overweighted with them in a wetsuit and open water, especially if I had TWO of them on my back!

Most of the ditchable weight that I need is to compensate for the positive buoyancy of an AL80. Being inherently neutral with an empty tank is something I can deal with (without a weight belt.)

Being inherently negative is, as I'm sure you know, unwise.

 

[MikeFerrara]

The latest data I have from PST lists the hp 100 at 1.3 neg when empty and the lp 104 4.8 neg when empty.

These are not the tanks for wet suit diving without (dare I say it) a second bladder. I have used the hp 100's with a wet suit and they worked just fine. Without weight and full tanks I was only slightly neg.

 

[Genesis]

on my "usual" openwater rig would mean I'd need no belt at all; I'd be neutral with an empty tank on the surface.

I carry 6lbs right now with an AL80 (SS BP + STA); I could swap to an AL BP to get rid of 4lbs of negativity if I needed to, but it looks like a single HP100 would be ok as it sits.

Double HP100s would be a bit negative and might prompt me to swap plates; that is assuming the STA and bands are roughly the same amount negative.

 

[pescador775]

I have two sets of tanks for general use; there are three PST HP 100's for tropical skin diving and three Faber HP 100's for wet suit/dry suit diving. The Fabers are very heavy at about 6.5 pounds neg buoyancy. The Fabers replace my old PST 95.6 cu ft/3300 psi, (-)6 lbs tanks which I used from 1977-99 for any diving requiring a suit. However, I don't use any metal plates or accessories which would significantly increase the negative weight bias. If the PST LP tanks are indeed (-)4.5 lbs I can understand their popularity for cold water diving. I say this because dry suit divers, in particular, seem to really like the Faber HP tanks. I'll take Mike's word on the PST LP's. However, like Genesis, I am a bit conflicted on 8 inch dia bottles. If I was 6'4" and 250lbs I might feel differently. My dive buddy during the years 1993-1995 used those tanks and I used to kid him about the 'hot water heaters' but he was unphased. He is 5'10', 170 lbs, a tad smaller than me. Those were his first and only set and as a California head boat habitue preferred for max low pressure fills on those boats.

 

[Scubaroo]

Anyone seen these tanks or heard an ETA? PST aren't even listing them on their website yet.