Tanks used for SM

[Dive-aholic]

From a newb that asked the same kind of questions . . . Decide your priorities and go from there.

In my case, the priorities were:

Out-of-water weight
The most gas I could get for the least tank
Usability - single or SM, fits on the dive boats I use, etc (ruled out 8" dia tanks)
Behavior as the gas volume gets low
No extreme buoyancy characteristics

I picked the Worthington X7-100 because -
- weighs ~ the same as an AL 80
- most gas I could get in a tank that is ~ weight of AL 80
- good tank for single or SM, according to half of ScubaBoard (who I asked) :chuckle:
- doesn't change trim characteristics as it gets low
- no huge buoyancy swing

Ruled out PSTs due to some supportability issues I was told about - didn't want to buy from a firm having issues.

On thing I missed was coordinating gas fills with my lds. Instead of discussing my needs, I simply asked if he could fill a tank to 3500. He said yes. However, that is only when he pulls out his gasoline-powered compressor; the electric one he has set to 3000 and it stays there. So, unless it is the summer 'load' time, I end up with short fills.

All the above because I have limited storage and budget and choose to not have a dozen tanks around . . . even if the idea is really appealing.

Hope this helps.

So, effectively you have 85s (actually 87s) when you fill your 100s to 3000. That's still a good amount of gas.

 

[Jax]

It works for me, and for lake / pool use I do the most ( ), I don't notice any 'shortage'.

 

[pdelannoy]

Jax,

Scubamagic fills to 3500 psi and also does custom blending. He's in Tempe.

PD

 

[metaldector]

I use Faber 85's LP and pump them to 3400 psi. The are easy to handle and hold a good bit of gas. I had PST95's which were a lot heavier and didn't give me much additional gas for the hassle of humping them into the water. I know one SM diver who uses PST130 LP's, too much weight for me.

 

[tbone1004]

so why not just buy HP100's and then get 85's if you get short filled so you aren't essentially hydro'ing your tanks every time you fill them?
4000psi is hydro pressure on those LP tanks and filling them to 38 so they cool off to 35/36 can't be good for them. I'd just as soon suck up the extra 3lbs on land to extend tank life. The 100's are a hair shorter though, by about 2 inches, so that may be a tipping point for some.

 

[FWADIVER]

so why not just buy HP100's and then get 85's if you get short filled so you aren't essentially hydro'ing your tanks every time you fill them?
4000psi is hydro pressure on those LP tanks and filling them to 38 so they cool off to 35/36 can't be good for them. I'd just as soon suck up the extra 3lbs on land to extend tank life. The 100's are a hair shorter though, by about 2 inches, so that may be a tipping point for some.

LP tanks are tested 10,000psi 10,000 times. There is tons of history of overfilling in cavecountry with no negative effects. The LP tanks in the US are rated to higher pressures in other countries.

 

[Jax]

Jax,

Scubamagic fills to 3500 psi and also does custom blending. He's in Tempe.

PD

I heard, you lucky Phoenix area people! :depressed:


Seriously, it's not a problem. I get more gas than an AL 80, and when important, I can get the full 100.

 

[rigdiver]

LP tanks are tested 10,000psi 10,000 times. There is tons of history of overfilling in cavecountry with no negative effects. The LP tanks in the US are rated to higher pressures in other countries.

Liability is a finicky creature. I've gotten 4,100 psi in "cave country" without asking for it. Skeered me.

 

[FWADIVER]

Liability is a finicky creature. I've gotten 4,100 psi in "cave country" without asking for it. Skeered me.

My buddy got 4700 which cooled to about 4500 once (accidentally set the compressor to manual instead of auto) Was nice for him to come up from the dive with 2400 still in his tank. Only think that would scare me is if the burst disc let go. I hear they are usually loud enough to make you need new underpants.

 

[tbone1004]

I'm not saying they can't be overfilled and I know they've been doing it forever in cave country, I just don't see the benefit of buying new LP tanks when you can buy the HP versions of the near identical tanks for about the same amount of money and often time cheaper. People seem to have the scared thought of "underfilling" but with LP's you don't know exactly what you'll get either so you plan low and adjust if you get higher. That's all I'm really saying. The thought process against HP tanks is skewed