dry suit inflation options

[nimoh]

With my impending trimix training on the horizon, I am looking to go argon for my drysuit.

I have been looking specifically at the Highland system, and the DUI system.

What I mostly like about the highland system is that I can buy the parts in pieces including choosing a tank size. I don't plan on buying a mounting harness in favor of mounting it on my backplate with piece of webbing and shock cord. I like the idea of getting a larger tank (14ft3) so that I can get in a few dives before filling, and to prepare for longer dives in caves when I might be up and down a bit more.

On the DUI system, I like that the valve handwheel comes straight off instead of at a 90 degree angle. Seems like slightly less of a snagging hazard, but probably minor.

Based on this, I have a couple of main questions, but appreciate any feedback

1. is a 14ft3 too big, and should I consider a 6 or 8, and only get a 14 when I actually need the extra gas?

2. is the handwheel on the DUI system harder (or easier) to manipulate when suited up?

 

[rjack321]

I don't know of any 8cf suit inflation tanks (steel?). The AL14 tanks are no longer made by Luxfer but you can sometimes find them used. So your new choices are: 6cf and 13cf, both 3000psi aluminum.

The first thing you need to find out is, can your shop fill argon to 3000psi? If not then you are stuck getting a 13cf cylinder and (trans) filling as best they can. Or use air in a 6cf cylinder.

The 13cf (and 14cf) are big bulky things which are really overkill for open water deco dives. Assuming you can get it filled, get a 6cf with a normal valve. There is zero risk of 'snagging' a side mounted valve knob since in open water deco diving you'll have deco bottles on which cover up the argon bottle anyway.

If its a long drive to get the bottle refilled you might consider the larger 13cf size since you can get 3 or 4 dives out of that. Better is 2x 6cf though. The 13cf cylinders are really the worst of both world's - bulky and big but 3000psi and not full from merely transfilling.

 

[nimoh]

I don't know of any 8cf suit inflation tanks (steel?). The AL14 tanks are no longer made by Luxfer but you can sometimes find them used. So your new choices are: 6cf and 13cf, both 3000psi aluminum.

sorry, I meant to type 13cf as opposed to 14.


Worthington makes a 8cf cylinder with a service pressure of 2015. The way I figure it, 8 is better than 6, but a little leary about overfilling aluminum, so I would be using it as an 8.

The first thing you need to find out is, can your shop fill argon to 3000psi? If not then you are stuck getting a 13cf cylinder and (trans) filling as best they can. Or use air in a 6cf cylinder.

all of my fills locally will be at one of two places, and at both argon fills are through a booster, so 3000psi is not a problem.

The 13cf (and 14cf) are big bulky things which are really overkill for open water deco dives. Assuming you can get it filled, get a 6cf with a normal valve. There is zero risk of 'snagging' a side mounted valve knob since in open water deco diving you'll have deco bottles on which cover up the argon bottle anyway.

If its a long drive to get the bottle refilled you might consider the larger 13cf size since you can get 3 or 4 dives out of that. Better is 2x 6cf though. The 13cf cylinders are really the worst of both world's - bulky and big but 3000psi and not full from merely transfilling.

thanks, that is exactly my concern about the 13cf bottle, that it is just too bulky on a dive.

Also, good point about the stage bottle protecting the argon bottle, although I didn't see the snagging hazard as a big deal, just that the DUI system seemed to be slightly less of one.

 

[Peter_C]

I like the smaller size of a 6cf better and just own two bottles. *shrugs*

 

[c5diver]

whats wrong with the Alum 8 cf 2015psi size wise its an inch bigger around same height

 

[rjack321]

whats wrong with the Alum 8 cf 2015psi size wise its an inch bigger around same height

Never used one.
But honestly IMO its better to have the same size plate mounting as the rest of us. I could loan you a 6cf but 8cf would have too big a strap. 6cf is fine for 1, 2, or even 3 dives (depending on your personal suit use patterns and depth). 8cf would probably be a 2 or 3 dive inflation cylinder but require custom mounting hardware/straps. Is it worth it to have an occasional 1 extra dive between fills in exchange for not being able to borrow or rent inflation bottles?

 

[nimoh]

another good point.

I usually make it out to Seattle every summer, and last year was able to borrow tanks...perhaps I will need to look at borrowing an argon tank as well

 

[boulderjohn]

If you can get boosted argon, then what follows doesn't really matter to you, but perhaps some other reader might find it useful.

I had to deal with unboosted argon quite a bit. After I figured out that I could not tell much difference, I used "airgon"--I put in whatever argon I could, and then put it on the compressor to top off with air.

When I was doing multiple dives out in the field with no access to argon, I would eventually have to top the tank off with air transfills. That was when I started wondering how much benefit I was really getting from the argon. An argon bottle filled with air usually felt just fine.

Today I will only bother with argon if I am going to dive some pretty cool water, which I haven't done for a while now. Otherwise, I just use air.

 

[rjack321]

Practically speaking, argon is rarely if ever "warmer". Air works just as well for most dives. For really cold things some people report feeling like the chill overtakes them a little slower with argon vs air.
In any case you need suit gas. 6cf is fine for open water diving. Modest cave diving still does fine with 6cf (swimming or scootering in JB for instance). Lots of deep ups and downs in a cave with multi-hour deco obligations, or remote from refills would be a good tme to upsize. I'd resist the urge to get some big honky inflation bottle now "to grow into". By the time you are doing huge cave dives requiring >6cf of inflation gas you'll have a whole stable of tanks and getting a suitable cave diving suit tank will be no big deal.

 

[nimoh]

thanks for all the input. I think I am convinced that the 6 is the way to go.

Also, even though I have access to boosted argon, "airgon" might work well in a pinch.