Advice wanted on setting up bank configuration

[Billy Northrup]

There was ounce a scuba shop operator here that had this amazingly complex array of banks, tanks, manifolds and compressors. So complex in fact he was the only one who could operate it. Often when shop help tried sometimes things like back filling between various banks happened. Do you make money tending tanks and knobs or the customer?

Any location is going to have a space, client/volume profile. Are you filling AL80's or more boutique tech centric? Do shop constraints create irritating compressor noise around the customer? Here in California some locations have a significantly higher on peak power cost, I mean HIGH. With electricity cost(maybe), time, demand and temperature it's about managing over mechanics. Have the closing crew queue the empties up, come in the morning fire up the compressor, open the whips and let her run fill the stragglers as they come in. Top the banks off, rentals are full and let the day begin.

Personally I prefer regulated 3500 and 3000 filling stations (two banks) each behind a bank. Check tank, whip it, in the water bath and get the customer in front of new gear, up coming opportunities, training and what they saw on the last dive. Then if no bite it's time "lets get you checked out" preferably with an air fill card and shop calendar of events. You hand the customer a cool and consistently filled tank with face time. You hot fill someone they tell everyone, in all fairness, I do too!

 

[TN-Steve]

I want to thank everybody for the great info I'm getting. I apologize for not getting back sooner, but we are starting up the busy season here and I've been running like crazy getting the details attended to.

I'll reply and expand on some of the posts coming up in the next day or so, but for now I thank all of you.

Steve

 

[Got2Go]

Are the 12 x 4500psi cylinders a done deal? Or can that be changed at this point?

 

[TN-Steve]

Are the 12 x 4500psi cylinders a done deal? Or can that be changed at this point?

That's pretty much a done deal. Currently running 8 in a 8x1 configuration and manually working the cascade off the tank valves. I've got 8 more on hand, 4 are going to be dedicated for when I get to spend more of the owners money and get my continual blending Nitrox setup, and 4 are going for the new bank when we build our new structure.

What do you have in mind, because I'm nothing if not open to ideas.

Steve

 

[Got2Go]

Some rough ballpark numbers.
If the compressor is running during fills, obviously these numbers will go up before the bank is ineffective.

Simple option: 1 bank of 12x 4500psi cylinders (assuming they are 444cf each) - This should allow you to fill about 33 AL80 from 500psi to 3,000psi.

2 bank option: 2 banks of 6x 4500psi cylinders - This will allow you to fill about 45 AL80 from 500psi to 3,000psi.

3 bank option: 3 banks of 4x 4500psi cylinders - This will allow you to fill about 50 AL80 from 500psi to 3,000psi.

4 bank option: 4 banks of 3x 4500psi cylinders - This will allow you to fill about 56 AL80 from 500psi to 3,000psi

The more you divide your cylinders into smaller banks, the more air you will be able to utilize from them, at the cost of making the system more costly and complicated to operate. Basically, I recommend going with the option that covers the fills you need before starting the compressor, and gives you a little buffer for spikes in fill needs. Anymore than that and you are adding cost/complexity to fix a non-existent problem/need.

This works if compressor wear/maintenance is not an issue (all bank cylinders filled to 4500psi.).
If it is an issue, then I would suggest getting some low and mid pressure cylinders (2400psi/3600psi) to add to the bank system.
That way you have low/mid/high pressure banks, and the compressor is mostly filling low/mid, and then a shorter amount of time filling the high bank to 4500.

In addition (others have mentioned some of this)
Use check valves on each whip to prevent cross contamination.
Use a regulator for your fill pressure, if you don't have one already.
I would add more whips to this system. Perhaps a total of 6-8.
I would also add gauges on the fill panel to show pressure for each bank. While not necessary, it is handy to have for a number of reasons.

 

[RayfromTX]

Some rough ballpark numbers.
If the compressor is running during fills, obviously these numbers will go up before the bank is ineffective.

Simple option: 1 bank of 12x 4500psi cylinders (assuming they are 444cf each) - This should allow you to fill about 33 AL80 from 500psi to 3,000psi.

2 bank option: 2 banks of 6x 4500psi cylinders - This will allow you to fill about 45 AL80 from 500psi to 3,000psi.

3 bank option: 3 banks of 4x 4500psi cylinders - This will allow you to fill about 50 AL80 from 500psi to 3,000psi.

4 bank option: 4 banks of 3x 4500psi cylinders - This will allow you to fill about 56 AL80 from 500psi to 3,000psi

The more you divide your cylinders into smaller banks, the more air you will be able to utilize from them, at the cost of making the system more costly and complicated to operate. Basically, I recommend going with the option that covers the fills you need before starting the compressor, and gives you a little buffer for spikes in fill needs. Anymore than that and you are adding cost/complexity to fit a non-existent problem/need.

This works if compressor wear/maintenance is not an issue (all bank cylinders filled to 4500psi.).
If it is an issue, then I would suggest getting some low and mid pressure cylinders (2400psi/3600psi) to add to the bank system.
That way you have low/mid/high pressure banks, and the compressor is mostly filling low/mid, and then a shorter amount of time filling the high bank to 4500.

In addition (others have mentioned some of this)
Use check valves on each whip to prevent cross contamination.
Use a regulator for your fill pressure, if you don't have one already.
I would add more whips to this system. Perhaps a total of 6-8.
I would also add gauges on the fill panel to show pressure for each bank. While not necessary, it is handy to have for a number of reasons.

Great post. Thanks for doing the math and taking the time to explain the consequences of the different options. There are, of course other options that involve unequal distribution of the banks but you went complex enough unless there is indeed a preferred distribution that you would use. I would assume you would not make the choice to fill all 12 to 4,500 unless you had to in order to meet peak demand. I would perhaps look at 2 banks of 3 filled to 3,600 and two banks of 3 filled to 4,200 if I was mostly filling AL80 to 3,000 and some steelies that might want 3,442. Of course as you said, the planning starts with the demand and then considers the compressor maintenance cycles, etc. Again, great post.