Bank Bottles, are they really worth it?

[Jeff Pack]

Something I was just thinking about, you can only store air so long, how long can you leave air in the bank bottles before having to recycle it?

[CaptnJack]

Something I was just thinking about, you can only store air so long, how long can you leave air in the bank bottles before having to recycle it?

Only so long? Who told you that?

For all practical purposes its forever. Don't worry about it.

[CaptnJack]

Most of my manifold, its hard to fit it in one pic

Compressor feeds from the left, booster from the right.

[kdupreez]

if you have 2 x 4500psi storage tanks for a bank, you should be able to get some fills from it without having to run the compressor, especially if you have low pressure scuba tanks! then your setup would be awesome.

for just 2 tanks, all you need are a 3 hoses with JIC ends, 2x347 nuts+nipples (they are NPT) one 90 degree elbow JIC-NPT and one NPT-JIC branch and one final JIC-NPT union.. that should not run you more than $200 max..

Or, you can just come over for a beer and I can show you what I have and help you plan your system out.. I really love doing this stuff and would love to help you put it all together too if you want

you dont also HAVE to have check valves, but i would encourage one flowing into the manifold from the banks.. that way you dont get back-flow if you happen to connect something that has more pressure than your banks. The compressor should already have a check valve built into the PMV (pressure maintenance valve), but not always.. my bauer did not, but my coltri does..

In general banks help to not have to run-stop-run-stop-runs-stop your compressor for every little fill you want to do.. but also just having 2 bottles wont do yo a heck of a lot of good if you want 3600psi fills every time..
(BTW you also dont need a manifold block..a few simple NPT parts will do the job)

I run my compressor once a week for one hour and fill banks up to 3800psi.. (I bank 32%) then i can use the banks for a week, maybe two before having to run the compressor again.. granted I have haskel boosters to make it easier..

Here are some pics of my manifold setup and I can try and make a view drawings for you to help plan out your system based on what you got..

This here is the manifold.. my compressor is directly connected to the banks, then I have 5 sources on the manifold: Auxiliary, 32% Banks, Oxygen Bank, Helium Bank and Argon..

All of these sources have check valves so I dont accidental get back flow into my banks.. (i.e. Argon into my O2) the manfold goes straight out to the fill whips, as well as through the Haskel booster. (The booster is solenoid activated.. so flick a button and it boosts)


Here is mini my fill whips manifold that are connected to the booster outlet and the main manifold (via a check valve so i dont loop gas)

Note that I only have 2 fill whips and I find that plenty.. I also have an "auto off" cut-out switch in here to cut-out the haskel booster solenoid, in case I forgot the lines closed.. my Haskel can go to 20,000psi.. the hoses dont


And here is a pic of the entire not so organized yet man-cave.. 12CFM compressor, 32% mixing stick, 2 banks of 5tanks each,then mixed gas banks of 2xO2, 2xHelium and 1xArgon and haskel boosters.

[H20doctor]

Nope.. Dont do it. I built my banks out of dirt with a dozer

[kdupreez]

For your setup of only 2 bank bottles, you probably only need something as simple as this:
(Depending on your PMV you might also not need the check valve after the PMV)

This will also allow future expansion if you want to feed more inputs to the manifold..




And these are all the actual physical components you would need (minus a bank pressure gauge and compressor check valve)
With the exception of the line and check valve, you can buy everything from Western Fluids & Components and the PraxAir down the street from them..

[Jeff Pack]

thx!

Now one question though, your design above, the scuba tanks are always filled from the bank bottles.

So I couldnt bank EAN, and only fill air if I wanted to.

Am I mistaken?

[Jeff Kruse]

OK, I understand, Koos has a massive compressor and doesn’t want to run it for just 10 minutes to fill one tank so banks help for that situation. But, really Koos, when do you only have one tank to fill? Buy more scuba tanks and forgo the bank tanks.

Getting back to the OP: For the rest of us with sub 10CFM compressors, banks make our compressors work harder. IMO buy a few more scuba tanks so the compressor doesn’t have to work so hard.

Never have I turned the compressor on just to fill one tank. It’s always 2 or more.

I had 2 wips for a long time. That worked but three is much better. I always have tank that is low enough sitting around that I can dump all that HP gas into after the last fill. That’s turns out to be about 300PSI worth.

[Jeff Pack]

yea, I'm kinda leaning towards the dont bother with the banks. OTOH, on a hot day, etc, having the banks is nice, or just to top off a tank.

I can save abit by instead of getting a manifold, use pipe T's like Koos suggests. Plus, I dont need to fill the banks to 4500psi, maybe just to 4k.

But the one answer I havent gotten yet, is how long can I keep air in the banks before it gets stale, etc?

[Jeff Kruse]

4 scuba tanks should get you through the weekend and even if they just need a “top off” that’s still a lot of run time for four tanks.

Summer, really??? What week is that?

If your tanks are clean and dry inside (which they will be because your filling them) the air will last longer than the tank.

[kdupreez]

thx!

Now one question though, your design above, the scuba tanks are always filled from the bank bottles.

So I couldnt bank EAN, and only fill air if I wanted to.

Am I mistaken?

Yes, but thats easy to accomplish by adding a check valve and line valve combo directly from the compressor to the fill whips "manifold".

And like I said, with just 2 banks, if you have high pressure tanks, you wont get too much benefit from banks, unless you aim to just top off a couple of tanks.. with low pressure tanks you will have better results..

small compressors ini the 3-5cfm range is typically not built to be used with banks and they are fantastic for pumping straight into scuba tanks..

For example a 3.5cfm compressor on a yacht or dive boat.. they dont have banks at all and those are awesome compressors to keep you diving the whole day long!

And for air in tanks... if you dont plan to use the gas in the tanks for a few years.. then I's say maybe drain 'em.. but for the most part, its not an issue..

Just make sure you have your air tested.. I test mine about 4 times a year.

K

[airsix]

So I couldnt bank EAN, and only fill air if I wanted to.

Am I mistaken?

Yes, you are mistaken. You never want to fill with air. (I kid!)

Joking aside, I've got to comment on Koos' fill station. It's awesome. His diy mixing stick is so well tuned that it pumps out 32% consistently within 0.1% (yes, a tenth) in my experience as an observer. I've seen a lot of sloppy mixing, but Koos is so far at the other end of the spectrum it's crazy (in an awesome way).

[Jeff Pack]

And like I said, with just 2 banks, if you have high pressure tanks, you wont get too much benefit from banks, unless you aim to just top off a couple of tanks.. with low pressure tanks you will have better results..

Could you explain this one? A hi pressure tank can always be used as a low pressure, but not vice versa?

and BTW, thx so much everyone for dealing with all my questions...

[CaptnJack]

And like I said, with just 2 banks, if you have high pressure tanks, you wont get too much benefit from banks, unless you aim to just top off a couple of tanks.. with low pressure tanks you will have better results..

Could you explain this one? A hi pressure tank can always be used as a low pressure, but not vice versa?

and BTW, thx so much everyone for dealing with all my questions...

If you have high pressure scuba tanks and your own compressor you want them full right? There's not much gas stored between the 3400psi you need to acheive and the 4500psi storage pressure in your banks. You'll use up most of your capacity just getting your scuba tank from 1000psi up to 2500psi. I guess if you are diving hp119s or 130s that could be "full enough" for a dive. If you are diving hp80s or hp100s its not really much gas. You'd be better off having 2 4500 psi bottles for the top ups and some cheaper 2400 psi bottles to do the bulk of your filling. Refilling the 2400 psi bottles is easier on your compressor too.

[pensacoladiver]

I am about 6 months into owning my own compressor setup now. I started off with one fill hose and quickly moved to two. Reason for that was when my tank was full, I "could" get the hose swapped over to the next tank fast enough without shutting the compressor down, but the pressure built to abaout 4000 psi in the system. With two hoses, I dont have to worry about that.

I am going to put in a third hose soon enough. As far as use, I have a 5 CFM Bauer and go through anywhere from 8-15 tanks of gas a week. I typically drain most of them, then spend a few hours with the compressor running to fill them back up.

I thought about bank bottles, but I figured I would go through gas so fast I would not get anything from filling the banks. Also, I am in South Florida and there really isn't a 'best time" to run the compressor. My garage stays at about 28C al the time, even with the big fans blowing.

I mix my own Nitrox via stick and I rent 2 Oxygen bottles so I dont have to worry about running out on the weekend as Richard discussed earlier. I would like to say I was smart enough to know that in advance, but I learned that lesson the hard way from running out on the weekend.

[kdupreez]

I saw a couple of 4500psi storage tanks on Craig's list today..

Get those and a bank of 4 would be much more do-able..

[Jeff Kruse]

Again, unless the OP has to fill his tanks in the middle of the night or he has to only top off one tank why should he have a bank? It will only create more wear and tear on his compressor.

[Jeff Pack]

I saw a couple of 4500psi storage tanks on Craig's list today..

Get those and a bank of 4 would be much more do-able..

those bank bottles are mine..

[Jeff Pack]

Again, unless the OP has to fill his tanks in the middle of the night or he has to only top off one tank why should he have a bank? It will only create more wear and tear on his compressor.

I'm rather inclined to agree, although I dont have to fill to 4500, perhaps 4k only.

If I sell the banks bottles, fine, if not, I'll eventually plumb them in, as so far, I've never had the need to top off a tank, and thats the only real use I see for the bottles.