Home fill station for dummies?

[Jeremy Williams]

@tbone1004 I know it’s highly variable. I’ve been running this thing pretty regularly for the last 18 months or so. I might get 12 or even 15 psi of pressure gain in my 3L cylinder per cycle if I am boosting from a relatively high pressure supply bottle. I might get 1 psi per cycle if I am scavenging from the bottom of a tank of helium. I try to do more of the former and less of the latter. And the amount of drive pressure you need to get 1 cycle per second varies based on the relative pressure difference. That’s why I have an AE415-400 on the drive side of the booster so I can dial it in. But the volume of the drive stroke is always the same, so you can math the worst case which is pretty close to what I said... I think.

150 psi (max drive pressure) assuming displacement of the drive piston is 4” diameter with 2” stroke. (Insert joke here) I think those numbers are close. It’s napkin math, so it’s the right ballpark, but that’s about it.

 

[tbone1004]

@Jeremy Williams they quote the displacement of the boost chamber, but not the diameter, and they quite the diameter of the drive cylinder but not the stroke or displacement. Super rude...

 

[Jeremy Williams]

It’s almost like they totally did that on purpose so that we couldn’t create our own accurate model of the booster operation...

 

[davehicks]

I just looked at the specs on my shop compressor.

2HP
26 gallon
5.5CFM at 90psi

Is 5.5CFM enough to drive a booster?

I may have started with a bad assumption - that my shop compressor is beefy enough to drive a booster. Hmmm...

I'm running a Maximator booster with a compressor that is only 3CFM @ 90psi, but it's super quiet. I'm topping off 40cf diluent and 14cf O2 cylinders. This works pretty well, but below about 1000 PSI from my source gas it gets really painfully slow.

 

[broncobowsher]

For reference I run my Haskel at about 1 cycle every 2 seconds. It runs pretty happy there. I would have to remove the BC nipple and actually use that full ½" port if I ever thought about trying to run it that fast. I really don't see a need to run one that fast. For a production shop where time is money, faster the better, let her fly! But a home fill station, filling small bottles, slow is just fine. Even running slow I still generate heat in the bottles to the point I have to wait for a cool off when blending on getting a true fill. Don't need it running any faster. Doing bail out fills, that could be faster, but have not done one in over a year. So I really don't care.

 

[Jack Hammer]

A clean and properly lubricated booster air drive section will use less drive gas, boost higher, and boost quicker. On Haskels it's pretty simple and relatively quick for the mechanically inclined. Staying up on simple maintenance will not just give better performance, it will extend time between expensive rebuilds requiring parts.

 

[Miyaru]

Sometimes things go wrong

Not exactly a fillstation for dummies, but a professional divecenter in Belgium. A booster caught fire while transferring oxygen according to unofficial statements. Dutch news article with video: click

Most important and very fortunately nobody was hurt and the diveshop owner posted on Facebook he was okay.

Be careful out there.....

 

[Lorenzoid]

Sometimes things go wrong

Not exactly a fillstation for dummies, but a professional divecenter in Belgium. A booster caught fire while transferring oxygen according to unofficial statements. Dutch news article with video: click

Most important and very fortunately nobody was hurt and the diveshop owner posted on Facebook he was okay.

Be careful out there.....

I bought my drysuit from that dive shop.

 

[Robbyg]

Hats of to you guys. I read half of this thread and am in awe at the technical levels you guys have reached in this Hobby. In my field of Electronics it's impossible to know even half of the stuff. I never looked at Diving that way until I started to read some of these kinds of threads. One thing that does kind of baffle me is how do you guys know the level of unwanted gas contamination in these blends? I know you use several specific gas analyzers for the most common gases but I am not sure how you are measuring trace gases or are the levels so low that it does not matter?

 

[tbone1004]

Hats of to you guys. I read half of this thread and am in awe at the technical levels you guys have reached in this Hobby. In my field of Electronics it's impossible to know even half of the stuff. I never looked at Diving that way until I started to read some of these kinds of threads. One thing that does kind of baffle me is how do you guys know the level of unwanted gas contamination in these blends? I know you use several specific gas analyzers for the most common gases but I am not sure how you are measuring trace gases or are the levels so low that it does not matter?

The PSA machines concentrate to essentially 4.5x everything in the atmosphere except nitrogen. As far as partial pressures are concerned when breathing at the surface, that is equivalent to diving air at 120ft.
If you're using it for "pure o2" for decompression, then it's comparable to diving air at 200ft. Anything mix wise when using it for nitrox is somewhere in between.

While I certainly don't advocate diving air to 120ft or especially to 200ft, it is not due to any effects of the trace gases in your body, and everything to do with gas density and CO2/N2 narcosis.

We do use oxygen analyzers and some use carbon monoxide analyzers for normal diving, and in technical diving we will use helium analyzers, but those are the only gases we ever measure.