FS: Stainless Compressor 110 VAC

[rcontrera]

Moderator ...I don't know if I am allowed to post this here. If not, pull it.

OK ... I screwed up and built a very customized compressor about this time last year for a "friend" without taking a deposit and, of course got stiffed. I need to get this one gone.

It is an electric driven 3.2 CFM compressor mounted on a stainless steel base and outfitted with automatic drains. It was built to go on a boat and I had told my friend that he needed at least a 7KW power plant to run it and it turned out that he only had 3KW. I showed it at the Dive & Travel show in Tacoma last year and it reallllly needs a home as I am getting tired of going out and giving it a spin every month. It is new and has only been run for testing.

If one of my Northwest friends can help me out on this one, I will eat the stainless steel upgrade (a $350 value), eat the ground shipping (around $50) and toss in an extra filter cartridge. Total is $4040. Drop me a line at ray@rayzplace.com if you are interested.

The only good part for me in this little lesson in trust is that my "friend" was too embarrassed to get a compressor from me so he bought one of the gas "clones" from a dive shop at about $450 more than my normal Northwest price. Serves him right!

[rcontrera]

I just got reminded that this is a 2008 model so the price is actually $200 less ($3840).

Sorry.

[Mattleycrue76]

Ray I'm not financially able to buy this unfortunately. But I do have a question or to for when that day (hopefully) comes.

What would be involved in getting such a unit to pump O2 compatible air (I'm not sure of the correct term) for partial pressure blending?
How much would the annual maintenance costs be if you're doing say 150-200 fills or so?

[rcontrera]

While I am not a big fan of PP blending, oxygen clean air (OCA) is no big trick.

Start off with a compressor that gives grade E or better. The small Coltri is a $3309 machine and the small Bauer is $3811 and either will give Grade E for about 2500 cubic feet of air (they are rated more, but...). Neither machine has automatic condensate drains so adding them in is a bit expensive (the machine above has auto drains installed). The Coltri option is $650 while the Bauer doesn't have a factory option.

NEITHER of these machines is designed to pump up bulk bottles ... just individual scuba bottles.

Now, after your compressor, you can add in one of the cool "Hyperfilter" stacks for around $2000 or an economy OCA stack for about half that.

So, I guess to answer your question, a NEW OCA capable air system can be set up for as little as $4300. But compressor systems are scary! They continue to grow and evolve over time until they occupy all the space and suck all the money that you have available.

[Mattleycrue76]

Thanks alot for the answers.

NEITHER of these machines is designed to pump up bulk bottles ... just individual scuba bottles.

I'm curious, why is this? Is it because of the runtime involved to fill storage cylinders? Or the pressure?

[rcontrera]

In order to keep costs and weight down on the small compressors, the manufacturers have had to put lighter weight bearings and crank. While they can pump up to 4500 psi, they can't maintain that pressure for a long time without eating themselves up. By pumping smaller cylinders one at a time, the pressure can go up to max and then back down to nothing ... making the bearings say "ahhhhhh ... thank you!"

[CaptnJack]

1 filter in good condition is going to produce OCA or very very close. Its not hard at all. A backup filter is all you really need, for when you start to get breakthrough on the little primary filter. My backup filter is just a typical 16" LF tower with a triplex cartridge in it. "Hyperfilters" may be necessary for various reasons, but producing OCA is not one of them.

PP blending really sucks though. Its really bad with a home compressor and no booster, you will even up dumping mix which is like dumping time & money. Even with a booster its a pita to have to deal with pure O2 in everything (valves, tanks, etc) just to make 32%. Make a stick and continuous blend, its silly easy to do, uses up the entire O2 supply bottle, and its way easier to keep fewer bottles O2 clean. I have 28 cylinders at home, I keep some of them O2 clean in case I have to go to a PP blending shop for some reason, or because they are dedicated for deco gases. But the majority are just plain old air clean with CBed 32% or He + 32% trimix in them.

[rcontrera]

1 filter in good condition is going to produce OCA or very very close.

I agree ... for many compressors. The little MCH6 and the Bauer with the P0 have both proven themselves as good, but not great at filtering. Yes, the air out of a fresh filter is of excellent quality, but it doesn't take long to go past the OCA specs. However, if you have a bigger filter to start with (like the ones that come with bigger compressors), then the quality of air remains better longer.

I do like CaptnJack's idea of having the back up filter. A "hyperfilter" is nothing but a fancy back up filter that does additional filtering. The expensive ones actually flow air up the center of a special cartridge, filtering all the way up, and then back down the cartridge, filtering all the way down. This is supposed to scrub the air of any remaining hydrocarbons and moisture. If you use a standard filter, it is best to put a flow restriction on the outlet so that air remains on the filter bed longer, which gives it a better chance to "polish". While the short tower will work, a tall tower will work better and doesn't really cost that much more (when you consider the whole cost of the system).

What size compressor do you have CaptnJack?

[Mattleycrue76]

In order to keep costs and weight down on the small compressors, the manufacturers have had to put lighter weight bearings and crank. While they can pump up to 4500 psi, they can't maintain that pressure for a long time without eating themselves up. By pumping smaller cylinders one at a time, the pressure can go up to max and then back down to nothing ... making the bearings say "ahhhhhh ... thank you!"

Thanks for the clarification. I've always wondered.

[CaptnJack]

My compressor is only a 3cfm Alkins so a short 2nd 16" tower is fine. Rated rate for that filter is about 12cfm so the gas is moving slow in there. I change the little P0 sized primary filter when the moisture exceeds 20%. The P0 delivers nice dry gas and then pretty much within an hour there will be substantial moisture breakthru (but not oil or anything like that), just water vapor. To ensure that the primary AC stays dry enough, I change the primary filter at this time. I get between 8 hrs and 20hrs out of the P0 primary filter depending on the season & temps. At my annual pumping rate, I reach the rated capacity (12-13,000cf, 65hrs of compressor time) on the 16" tower about once a year. I replace this secondary filter at this time. The moisture strip in the 2nd filter has never shown any measureable humidity when I check it every few months or after 65hrs of use either.

This schedule seems to work for me, avoids any type of filter rotation (not recommended), has redundancy, and consistently produces really clean and dry gas.