HP Tanks - Never DIR?

[MASS-Diver]

It seems like most GUE trained DIR divers don't like hp tanks, part of this may be due to the fact that hp can create problems for TRIMIX divers.

However, are hp tanks always non-DIR for rec divers? In the DIR III video, George points out the problem of someone diving with a big heavy hp and a thin (or no) wet suit and, as a result, being overweighted and unable to swim their rig up in an emergency.

But, what's wrong with a hp tank and a drysuit? If I were using a al tank I would just have more weight on my belt. With 15lbs on my belt now I feel like I have plenty of ditchable weight and I can swim my rig around fine with no air. Do look dumb putting my halcyon bp/wings on a steel tank with their big DIR logo right behind my tank? Why am I doing it wrong?

I plan on going to doubles soon, but, I still think for certain dives I will stick with my hp120 and 40al stage so I would like to hear comments on this set-up, espically from those with a DIR background.

 

[Compressor]

I thin the GUE have alot going for them with alot of great suggestions and ideas I respect. However not every idea they have is right in my opinion. The case you mentioned is a perfect one. Just because something is DIR, does not mean everything else is DIW (Do it wrong). Another case is when they mention that HP tanks stress the regulators. I don't get it; my reg sisrated for the pressures they mention. Furthermore in Europe the tanks are rated over 4000 psi.

 

[pescador775]

Mass, good to see that you are thinking out of the box. Some European HP tanks are fairly heavy, too much so for doubles, IMO. However, the HP tanks most commonly in use are the PST which are often lighter and less negative than comparable LP tanks. Anyone who says that HP damages regulators is seriously behind the times. I'm sure the majors like Scubapro would have something to say about that. Even the old double hose two stage regs could be used at 3000 psi, all day, every day. The average single hose first stage is built like a brick. The offending HP seats in diaphragm regs that would upset occasionally at HP are long gone. As to trimix, the gas mixer is free to underfill a HP tank if he doesn't have a blender or booster suitable for the job. See the thread on PST's new E series 3442 psi tanks. They quit scratching their heads over diver culture and tried to fashion a product which would serve both camps.

 

[salty]

A big misconception about DIR is equipment


HP tanks are not non-dir. Diving steel tanks and a wet suit are. Too many people get the idea that standard equipment listed on the wkpp web site are the "Blessed" equipment choices.
Wkpp and most DIR divers use lp tanks because of there benifits are required. Hp tanks with the correct manafold or valves are not a problem.
GUE and Wkpp are two difrent things GUE does not say what brand of equipment to use only recomends styles and features that you should look for. Wkpp has strict rules for the simple reason that they have tryed it all. Diving at Wkpp is excelerated compaired to what most of us do. If a reg will not last a week at Wkpp it might last a few years with Joe diver. this causes a lot of problems because no one seams to understand this. People get naturaly defensive when they are told that the reg they just spent $500 on is crap and dangerous. Well chances are it will never fail and they wont have to remove a cover to clear it but who wants to take chances at 250 ft?
I had an opertuinity to sit through a lecture with GI3 as any one else who knows him will say he is plesent and full of information and will calmly explain his position even when faced with the most hard core anti-DIR diver. This is when the diffrences in GUE and Wkpp come out and a lot of the how and why's become clear.

Equipment dosent make the diver.

 

[Genesis]

HP tanks are not non-dir. Diving steel tanks and a wet suit are.

Which is a load of horse-manure.

This is one of the places where the DIR-zealots have adopted a position without thinking it though, and it points out where the line between reason and religion gets crossed.

The issue is proper weighting. How you achieve that is not relavent to the type of suit you wear.

The mass of the gas you breathe is a constant regardless of what the tank is made of. Steel or Aluminum doesn't change the buoyancy shift of the tank - that is ENTIRELY controlled by the buoyancy shift (or weight, if you prefer) of the gas inside.

Now LP steels CAN be unsafe with a wetsuit (especially a thin one!), but that's because LP steels are often SEVERELY negative EVEN WHEN EMPTY!

HP steels are (typically) close to NEUTRAL empty.

You must be able to weight for neutral at the surface when almost out of gas. If the amount of gas (measured as weight, not volume - He weighs a lot less than N2!) that you have on your back, when weighted for empty tanks, means that you are more negative than you can swim up at the START of the dive (say you jump in and discover your BC has a hole in it) then you need a REDUNDANT source of lift.

Such a source could include a drysuit. It could also include a liftbag, but using one for that kind of purpose is tricky at best. It does, however, beat sinking to the bottom in 2000' of water!

However, the issue is NOT the material your tank is made of. You can be just as dangerously overweight with a pair of AL80s on your back in the wrong conditions and weighted incorrectly as you can be with a pair of LP104s.

Ditching weight at depth is NOT a reasonable option. The reason is that as you start up your wetsuit will uncompress, and as it does you will get a runaway ascent with NO CHANCE OF STOPPING IT.

The "DIResque" argument about steelies and wetsuits is a load of bunk. The reasonable argument is whether or not you can swim up your kit with full tank(s) and a defective (punctured, etc) BC - if the answer is "no", then you need a redundant source of lift - NOT the ability to ditch some of your weight.

The material the tanks are made of is IRRELAVENT to the debate.

 

[MASS-Diver]

Thanks for the feedback!

As a posted I dive on air or NITROX now, but, in the future I will be learning to dive with TRIMIX. Assume my LDS can fill hp tanks (boosters etc)with MIX, are hp sOK? I though I read once (on this board) that some of the gas law get "screwy" at high pressures, any truth to that?

BTW, my original comment about ditchable weight was for if one was in trouble on the surface, not a depth. On the flip side ,I went to a weight belt after the first time I took off my BCD underwater and (wearing no weight on my body) I was supper positive.

 

[salty]

Mass Diver:


I dive HP tanks because thats what I own and a shop that does a fair amount of mixing will have the skill to mix HP tanks without a problem. BUT I am currently looking to switch to the LP tanks due to reciently putting togther a mixing wip and planning on mixing my own gas. The LP tanks make it easier for the home brewer.

As for the debate over diving steel wet, as soon as I get the numbers togther Ill post some thing unless someone beats me to it.

 

[salty]

First I would like to thank Genesis, I had too think for a while to rember the awnser to this one.

If you are weighted properly you should be able to maintain 10 ft with near empty tanks and no air in the bc or suit(if diving dry). This goes for dry or wet.

If diving wet you need enough weight to over come the boyency of the tanks and your suit. At the end of the dive this should be around 5-10 pounds for the suit and 4 pounds if diving double steel tanks. OK so far no problem, now lets check the start of the dive. You hop in with 15 pounds on your waist and 20 on your back due to the weight of your tanks. At 100 feet your suit has compressed and has no redundent lift. So you add air to your wing and find out there is a hole and it wont hold air. Now you have to swim up 20 pounds because your weight belt is off(ditched because no one is swiming up 35 pounds from 100ft). Back at 40 feet you cant slow down because you sucked down half you tank because it was so hard to swim up that weight and your CO2 retention is at its peek. So your too light to maintain depth and you pop to the surface. Sounds like a sucky day to me.
Why take the chance?
That is why it is a bad idea to wear steel with a wet suit.

Now if you doing a 20 to30 foot beach dive its not going to make much of a diffrence. But were talking about a system that is ment to work every where.

 

[Aquamaniac]

Genesis once bubbled...


Which is a load of horse-manure.

This is one of the places where the DIR-zealots have adopted a position without thinking it though, and it points out where the line between reason and religion gets crossed.

What group of DIR divers are you talking about?

There IS a differance.

Dave

 

[Compressor]

The greatness of posts included under this thread really points to the expertise and objetivity of many of the people on this scubaboard. Congratulations you fabulous divers.