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SurfLung
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Re: Portable Compressor Realities

Tue Sep 24, 2019 9:33 am

rx7diver wrote:
Mon Sep 23, 2019 3:44 pm
captain wrote:
Mon Sep 23, 2019 10:12 am
First you need to buy the cherry picker to load and unload the 6000 psi cascade cylinders.
A two-wheel hand truck or dolly (is that what they're called?) and a ramp could be used to move the cascade cylinders, one at a time, into the truck bed. Be sure to use the valve cover/cage, and be sure to chain the cylinders in place (to keep them from shifting around). Do you think DOT would have any problem with this? We'd need to check.

If the 6,000 psig cascade bottles prove too massive (I don't have any experience with them), then use 4,500 psig cascade bottles (I do have experience with these), instead, which weight ~150 lbs each and hold ~450 cu ft of air at their service pressure.

(The quick and dirty Excel example I shared here a few months ago can be tweaked to show just how many classic 72's can be filled from empty to full + 10% using only a few of these cascade cylinders.)

rx7diver
Thanks rx7diver,
- Actually, I was using AL80s and an HP80 to cascade fill my first set of Twin 38s (1800 psi) a few years back. And I did it that way with a few more tanks when we did the Sea Hunt Forever shows. Its amazing how many fills you can get on low pressure tanks... Especially when you breathe them down to zero psi!
- As for the bigger cascade tanks, I think I run into the problem that my little compressors aren't supposed to pump that high of pressures (4500 and 6000 psi). On the other hand, I don't NEED them to be that high to fill my 1800 psi tanks.
- BUT... The original reason for bringing a compressor is so you don't have to bring a bunch of tanks! Aaargh! My brain hurts!
SurfLung
The Freedom and Simplicity of Vintage Equipment and
Vintage Diving Technique are Why I Got Back Into Diving.

rx7diver
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First Name: Ronald
Location: Columbia MO

Re: Portable Compressor Realities

Tue Sep 24, 2019 10:55 pm

SurfLung wrote:
Tue Sep 24, 2019 9:33 am
Actually, I was using AL80s and an HP80 to cascade fill my first set of Twin 38s (1800 psi) a few years back. And I did it that way with a few more tanks when we did the Sea Hunt Forever shows. Its amazing how many fills you can get on low pressure tanks... Especially when you breathe them down to zero psi!
SurfLung,

I do something similar: I separated my doubles-manifolded PST HP 120's (each ~120 cu ft @ 3,500 psig)--probably forever--about ten years ago. I now use these two HP cylinders and my OMS (Faber) LP 125 (~125 cu ft @ 2,640 psig, pumped a bit higher) as three cascade cylinders for my one and only steel 72, my OMS LP 66 (~66 cu ft @ 2,640 psig), and the occasional rental Luxfer Al 63 (~63 cu ft @ 3,000 psig).

Works like a charm!

rx7diver

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