Tell me what y'all think about this idea...

[SeaJay]

For a while now I've been kickin' around the idea of purchasing a compressor, but frankly, I don't have $1500 to go blow on one (and that's a cheap used one). Since I'd like the ability to do my own fills for a variety of reasons, I have this idea:

Why not get a pair of those tanks that they use at a fill station and just keep them filled and on a trailer or in the back of a truck?

The solution seems like a good one to me... I visit the dive shop less often (only when I need to fill my *big* tanks) and then I just fill my own tanks from that. I think it would end up being cheaper, too.

But the important thing is the convenience... And the fact that, done with a couple of these types of setups, I could mix my own mix, once I'm certified...

I can see it now... I get a pair of 4500 psi tanks and fill them with 32% EANx... Then I fill my own tanks from there. I think it would be cheap and convenient...

Thoughts from those out there?

What's the cost of those sort of tanks, and where can I get them?

 

[Ari]

He has an interesting setup as I recall.

Ari

 

[neil]

If you are thinking of the big K bottles used at fill stations, I don't recall ever seeing any that use 4500 psi. Just remember that you can only fill your tank if the pressure is higher in the big tank than in yours. You won't get many fills without a booster, which is BIG bucks. You could build a cascade system with multiple bottles that will wind up costing as much as a compressor and take up many times the space. Save your pennies and buy the compressor.
Neil

PS I've seen used K bottles go for a cupla hundred each.

 

[Scubamedicjoe]

hey neil is right I have built several cascade systems and with out several bottes prombly at least 6you wont get many refills and the cost would out way the production sorry no easy way around this .

 

[LUBOLD8431]

there are new storage bottles out there that are rated to 4500 psi. big steel goliath of a storage bottle. I wouldnt want to be moving those things around alot. Plus, they cost about 500-600 a piece new, maybe more. Not to mention the fact that the dive shop should charge you a significantly higher price for filling those things than your regular tanks. I think it would take you a long time to make your money back from buying those things, and you are not going to save that much on the air. Plus, you have to do all the grunt work.

IMO, dont bother with this plan Seajay. Save up your money, and buy yourself a nice NEW compressor.

 

[miesemer]

You might consider that trailer mounting these cylinders may require adherence to certain DOT rules. Also since they wouldn't be part of a stationary fill station you may be looking at visual and hydro testing more frequently.

 

[Dan Gibson]

A shop would either need to have a bank with higher pressures than 4500 psi (doubtful) or they will need to run the compressor for a really long time to fill them. Neither option is likely. A far as the booster goes, I doubt most dive shops have that option.

I seriously doubt you could get them filled at an industiral gas supplier either. Once they hear what you want it for, they will probably tell you no. That's after waiting several days for them to fill them.

 

[Bob Sherwood]

SeaJay
I'll give you a star for thinking about alternative solutions<G>, but it ends there. You need at least three 4500's cascaded together. Full, they will fill approximately. 6 alm 80's. after that, you start over. Not a cost effective option. The only reason stores have cascade systems it to save time when multiple people walk in at the same time. True you do realize a small wear/tare factor on the compressor with a cascade system. You are on the edge of a mountain looking at the beginning of "the snowball effect".
First get the compressor, then you want to upgrade the filtration system(for 02 compatible air) $3500 then comes the fill panel $1000 easy)and the cascade system$1500-$2000, the 02 bottles and the contract with the gas supply house(35-40$ a yr lease/$6-$8 a month each bottle, plus the cost of the gas, and delivery charges. (you can always save a few $ by schlepping the tanks around yourself) then add wear/tare on your vehicle, then you need more space than you thought for all the stuff, so now construction phase,. Don't forget the maintenance, compressor oil $50/gallon, filter changes $250 every 30 hours for standard filter, 6 months for hyper filter or 120K cft. electricity. Oh, and did I forget to mention, that once you get your system up and running, you become the best friend of every diver who ever heard your name, cuz SeaJay will fill it for you.........now enters liability.....even for your friends. Yeah SeaJAy, you should get one!!! What's that ??? What loves company?????? Best, bob

 

[SeaJay]

HUMM.

 

[Genesis]

Look, I have my own fill station in my garage.

Here's the facts for 'ya SeaJay, becuaseI just did this:

1. Compressor. Alkin 3.5cfm unit. $2500. 220V, single-phase, 20A breaker. Easy to wire for to a socket, so no permanent wiring required.

2. Lawrence-Factor Hyperfilter. I consider it essential. Others will not. Turns grade-E air into OCA. $1200. Cartridges are roughly $90 for it, but it handles 7000 cubic feet of air before changes. Your lungs will thank you.

3. Oxygen transfill whip, digital gauges (2; one for the O2 whip, the second for the compressor), second fill whip, quick disconnects (which I added after realizing how much nicer they made things on the HF stack and in general), and miscellaneous parts - $300. All made from pieces; you can blow more than $300 on the O2 whip alone if you let the shops rip you off. The hose, needle valve and brass fittings are under $50 - the most expensive part is the digital gauge ($100).

The entire setup should run you about $4,000.

O2 bottles here (K bottles, ~2600 psi full) run $16, and will fill anywhere from 20-25 AL80s starting from empty. If your bottle pressure is above the tank's pressure, and you refill partials, you can stretch this even further. If you have TWO O2 tanks, its even better. Tank lease is $60/year per bottle; do the math as to how much gas you're sending back in an "empty" (~400 psi is the "empty" point) as to whether you want one or two.

Compressor oil is $35/gallon (not $50), but the Alkin requires only ~250ml of oil, so a gallon lasts a LONG time. Changes are at 100 hour intervals - a LOT of gas. Valves/rings/etc need to be checked and possibly changed at 1000 hours - again, a LOT of gas. You'll probably never get to 1000 hours on a personal compressor before you're too old and gray to be diving

Electricity costs about SIX cents per tank.

Total tank fill cost is about $2.50 for Nitrox, and most of that ($1.50 or so) is filter consumption. Nearly all of the rest ($0.75 or so) is O2. The rest, all together is less than 10% of the total.

If you're paying $10/fill for Nitrox, you will pay for the compressor in ~500 or so fills....