Advice Needed About A Compessor

[Dry_Diver]

Hello,

I have been thinking for a long time now about the pros and cons about buying my own compressor for filling tanks. I do what I think is a fair amount of diving. I have been diving for a little over two years now and have logged over 200 dives. I dont really know the number over that, my log book is full and I have not bought another set of log sheets for it. I would think that the cost associated with buying your own would depend on just how many tanks I would pay to get filled compaired to the cost of maintaining a compressor to fill myself. If I take the average of 100 dives per year and then add to that the fact that my girlfriend will do around 30-40 dives with me per year. Her son will add another 10-20 to that. I come up with 160 fills at the regular price of $8.00 each (HP) That is $1280.00 in one year for fills based on an average.

Anyways, back to the questions....

1. What should I pay for a good compressor? I don't want the bottom of the line, this is my life I will be trusting to it. But I also don't want to refinance my house to buy on either.

2. What type of maintenance costs are there?

3. I have worked as a millwright in the past, did it for four years. Is the serviceing something that I can/should do myself?

If there are any other factors that I have not concidered and I suspect that there are, please feel free to point them out.

Any help is appreciated.

 

[pescador775]

No need to over-dramatize a compressor. It is just a reciprocating pump with several stages to achieve high pressures. If it will generate required pressure and volume in a reasonable time and has a competent filtration then the remaining question is price. The market for air compressors is varied, like the car market, and prices for a home SCUBA type unit can range $2000-4000. Accessories like storage cylinders are an additional expense if needed. Maintenance consists mostly of oil and filter changes, like a car. No need to check the battery, there is none. However, like any machine, it will eventually require parts and service. Therefore, a brand name compressor of good reputation is a better choice for all but gear heads. See this and compare value to the Aire Tex Atlantic:

http://cgi.ebay.com/Mako-Diesel-Por...ryZ16057QQssPageNameZWDVWQQrdZ1QQcmdZViewItem

 

[gxsr_sarge]

I was just going to post the same question! I'm going the technical route and do about 100-150 dives a year PLUS those of my wife and kids (and their friends). For me, it's not just the hassle and expense of taking the tanks to the LDS (now have 10 tanks including steels, doubles, stage bottles -- and counting) but mostly having to plan around their open/close schedules (many closed on Sundays) and trying to get tanks filled for back-to-back days. Sometimes their compressors are down or they are packed with people. It really would be nice to DIY.

I have the additional few questions:

-How does the requirement of Oxygen Compatible Air (OCA) complicate things?
-What are the best brands/makers for home use?
-Do they pump to 3442 PSI?
-It would have to be an "upgradable" system for future Nitrox and Trimix blending.

Any advice would be greatly appreciated.

(Man I hope my wife doesn't find out I'm thinking of turning our garage into a fill station!)

 

[#1 Aquanut]

I recommend watching ebay and craigslist, also check out government liquidation sites. Do your home work, some of the compressors the military sells are hard to get parts for. I found a compressor on craigslist, 1956 Cornelius, 1.8cfm at a max of 3000 psi. You won't believe it but the thing starts on the first pull every time. You need to use special non petroleum base oil in the compressor. You can have the oil tested, which will let you know if you're having problems inside the compressor. You can also have the air tested $100.00 a test or you can pay an annual amount. The compressor is well worth the cost, think in terms of your time driving to the shop, waiting at the shop, and then you wind up buying things that you really don't need. If it is mobile, you can take it to remote sites and not have to take a dozen tanks for the weekend. I paid 400.00 for mine, I've replace a gauge and 2 valves, I've had to rebuild the fuel system and added a snorkel for the air intake. I'll also, be adding a second yoke. My compressor is a very slow fill. My LP95 with the leaks in the two valves I currently have takes 50 min and there is no worry about the tanks getting hot, this time to fill should get a lot better once the leaks are fixed. When the cfm's are higher like 4 to 6, you'll have to worry about your tanks getting hot and you'll want to fill two tanks at the same time. Compressor parts can be located on ebay and craigslist, my pressure switch shuts the engine off at 2400 psi. I've just purchased a used adjustable switch that goes to 3000psi. I'll be setting the adjustment to 2800 psi. The dive shop, that I go through, helped me with my filtration.

Good luck, I'm very happy with my purchase and I'm learning about the air I breathe. Not having to depend on a dive shop that may or may not service their compressor is added security.

 

[Dry_Diver]

Thank you very much for your response #1 Auquanut. That was a lot of good information. The one thing that I didn't see an answer to was the cost of the filters. I have been reading about cartridges that you can refill that cuts down on the cost, but no one is saying how much it costs to refill these cartridges. Any in site ???

 

[gxsr_sarge]

Thanks as well Aquanut - In case you don't have it, you might also want to pick up the Oxygen Hacker's Companion. It contains tons of useful information about "do it yourself" mixing and handling of O2 and Helium. I love it when hobbies sprout sub-hobbies!

 

[realdiver7]

Most of my cylinders are Worthington X7-100 steel (100 c.f.) with 3442 psi operating pressure. This is the Alkin compressor I've been using, it will pump up to 4500 psi, and I have been very satisfied:

http://www.scubaboard.com/forums/ge...-fs-compressor-scuba-like-new-good-price.html

If I didn't teach and dive so much, I would keep it. I have 3 small filtration canisters instead of one large one, and I can refill my own canisters with Vaporshell 13x moisture absorbent, activated charcoal and a little bit of hopcalite for approx. $10 per canister (which is very cheap compared to buying commercial filters). I believe this equates to a little less than half price if I used a large canister (tower) and bought commercial filters, but your results may vary. By keeping the system charged with some air pressure when it's not running, the on-board filtration lasts approx. 20 hours, but the amazing thing is that the additional filtration can last more than twice that much (50+ hours), depending on humidity, etc. This means that I don't have to change all 3 canisters at the same time, which saves even more money. Since the compressor only has 155 hours on it, I'm still in the process of determining total filter life.

To recap some of the advantages, I have copied this from my ad:

The BEST things about having this compressor are the pure convenience of never having to drive across town to get air fills on the dive shop's schedule, never having to wait in line for air, always having air available to me regardless of how late I get back from a dive trip, filling cylinders as full as I want them (never being short-filled), filling cylinders that the dive shop may refuse to fill if they decide the cylinders don't pass Viz (when in fact they do pass), never having to worry about getting air fills if the dive shop gets pissed off at me for some obscure reason, getting the exact Nitrox concentration that I want any time I want, being able to top off any cylinder, including pony cylinders without being charged for a full cylinder, being able to save money on air fills (especially since I can refill my own filtration canister), etc., etc. I can NEVER see myself going back to the hassles of buying air fills somewhere else.

Hope this helps.

Thanks!

 

[crpntr133]

Owning your own compressor is a convenience. You aren't going to save a ton of money on fills like most think. By the time you pay for the gas/electicity, oil and filter, etc, you will be close to the LDS price. But it is nice not to have to rush to the LDS before they close. Plus since I own LP tanks they get pumped a few extra PSI.
I paid $1800 for mine and that included a new 6' fill whip with gauge.
If the compressor was meant for scuba then there should be no problem pumping to 3442. But be sure and watch for that. I am willing to bet that there is an exception.

 

[gxsr_sarge]

Realdiver7, your ad lists Grade E air and indicates that it's factory approved to direct-fill Nitrox tanks. Do you blend Nitrox? Can your compressor model be adapted for use with O2 cleaned tanks (i.e., Oxygen Compatible Air - "OCA")? By the way, I'm interested in your compressor. Sorry for the newbie questions as I'm just starting off in my research.

crpntr133, what make/model do you have?

 

[gxsr_sarge]

Also, Dry Diver, I didn't mean to hijack your thread. It's just a real coincidence that you posted it right when I was getting ready to list the same question.