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From: trey@ne*.co* (Trey)
To: "Ian Puleston" <ian@un*.co*>, <techdiver@aquanaut.com>
Subject: RE: OMS vs PST tank specs
Date: Fri, 23 Mar 2001 06:40:42 -0500

volume is volume, so that part you have right. Obviously you do not want to
hear the rest, but I will tell you anyway. For ocean or cave or anything
else, only a moron dives steel with a wetsuit, Faber or PST. There is no way
to balance the rig like this, and the compression of the body at depth will
negate any perceived surface buoyancy characteristics, and that is a fact.
Aluminum has a pos to neg swing that allows a belt to be used to offset and
drop in an emergency ( or the light ). Double 80's with a stage is the same
as 104's gas wise, and far more sensible not only diving with a wetsuit ,
but walking around on a boat or getting in and our of the water.

For dry suit diving anywhere, the PST offers a better buoyancy fit as a pair
are -9 in fresh vs neutral for the Faber. To offset a proper shell suit with
insulation takes between 20 and 26 pounds, and that is achieved by the
tanks, the plate, the light, and the regs, leaving the diver neutral at all
depths with little or no gas, and negative by the amount of the gas when
full, plus or minus a little depending on the insulation and the diver, with
the light being droppable in an emergency to get up.

For Faber diving, one needs to make the Faber more negative by a steel plate
or wedge under the plate. The Fabers are otherwise lighter. I use Fabers as
doubles with my rebreather as that device has buoyancy characteristics which
allow the lighter tanks.



-----Original Message-----
From: Ian Puleston [mailto:ian@un*.co*]
Sent: Thursday, March 22, 2001 2:08 AM
To: techdiver@aquanaut.com
Subject: OMS vs PST tank specs


I was looking at the tank specs for OMS and PST tanks LP tanks the other
day. PST say their 104 has a capacity of 104 cu ft at 2640psi, and weighs
45lbs without valve. OMS say their 108 has a capacity of 112 cu ft at
2640psi, and weighs 41lbs with valve. Both state a liquid capacity of 17
litres.

Firstly, two tanks with the same liquid capacity cannot have different air
capacities at the same pressure, so someone ain't telling the whole truth -
anyone know how the volumes really compare.

Secondly, the significantly lower weight of the OMS tank seems to make it a
better choice for ocean diving, but up to now I've been lead to believe that
the PSTs are a better choice. Anyone have any opinions between the two for
ocean diving?

I got the specs from the manufacturers brochures, but FYI they're also to be
found at:

OMS:
http://www.h2oadventuregear.com/productinfo/tanks.html (note the PST specs
here are wrong).

PST:
http://scubadiving.com/gear/27tanktips/stats.shtml
http://www.pstscuba.com/aaspo.htm (not much detail)

Ian

P.S. - I know there was a recent thread about ALs for ocean so don't start
that over again - I just want to know how these two compare for ocean use.

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