Thinking of buying a compressor...

[Windknot]

Why dont you two get together and write a primer on home fill stations and fill banks.

I've read the Oxygen Hacker, but with the advent of home made nitrox sticks for preblending EAN (and did I understand that the same can be used for Helium as well?) will those make the idea of partial pressure blending obsolete? That is...given one's desire to invest the money and time to purchase quality compressors, storage tanks for the banks etc?

I'd be sure to read it if you ever write one....(We just got the final figures on the new house we're building and I WILL get my pole barn!!! Which, like in an embassy...anything that is said or done in there will have diplomatic/wifely immunity from prosecution. )

WK

 

[omar]

Maybe someday (my way of saying it will probably never get done).

I will say that before I got my compressor I seriously considered getting a RIX SA-6. The only thing that stopped me was what I considered the less than optimal cooling and the increased maintenance frequency that was said to be required if I was pumping helium through it. The cooling and upkeep info was told to me by the dealer. My trade off is the incresed filtration towers when compared to the RIX oil-less. After keeping up with what UP is doing I may make a different choice if I had to do it again.

Yes you can use helium in a preblender as well. Very easy to do. I still do PP blending on occasion. Like my 50% .

omar

 

[Aviatrr]

I've read the Oxygen Hacker, but with the advent of home made nitrox sticks for preblending EAN (and did I understand that the same can be used for Helium as well?) will those make the idea of partial pressure blending obsolete? That is...given one's desire to invest the money and time to purchase quality compressors, storage tanks for the banks etc?

If you haven't seen it already, check out www.deeperstuff.com. On the bottom left hand side of the page, check out the links for "Garage Mix".

Mike

 

[Uncle Pug]

Originally posted by Aviatrr
If you haven't seen it already, check out www.deeperstuff.com. On the bottom left hand side of the page, check out the links for "Garage Mix".

Mike... that isn't your stuff is it?

 

[WreckWriter]

Originally posted by Uncle Pug

Mike... that isn't your stuff is it?

That's Z's station. He's a buddy of mine down here in South Florida. It's a beautiful setup, I've seen it. Cost like hell though, mostly because of his Haskel I think.

What a minimalist setup for mix gonna cost?

Tom

 

[omar]

I have read this treatise on blending and I don't think that I have seen a more elaborately constructed incomplete one sided discussion about PP blending anywhere else. I really liked the statement that a helium analyzer is not cost effective in this "cost is no object" system when there at least 8 unnecessary lines, valves and gauges, if not more. There are a number of other contradictory and inconsistent statements in this series of articles as well.

The only thing that this system can do that continuous blending can't is boost O2 to high pressure - a questionable need, and in the case of this system is the $10,000+ cost worth it.

In just a quick look a number of design problems stood out as well. Since there is no regulator to control the outlet side of the system I assume that the scuba line valves are used to control the flow of gas. The use of scuba valves in this setup is a poor choice. You need slow-opening globe or needle valves which contain seats made from oxygen-compatible polymers. Fast-opening valves should NEVER be used in 02 systems.

Large mixing systems and manifold bars should be properly grounded to prevent static electrical accumulation. Especially when it is set in a tin shed at an airport in Florida. You need to keep 02 delivery lines as short as possible. The longer the delivery line, the greater the risk for adiabatic mishaps. This risk can be lessened by keeping lines as short as possible and by using metering orifices to control flow rates and surges. I would also install check valves which are not evident.

omar

A minimalist setup for EANx will cost $200-$250 plus compressor.

 

[Aviatrr]

Mike... that isn't your stuff is it?

My stuff? I wish.....I would love to have a blending station in my garage, but I am not in a position to do that yet. I don't think I will put mine in the hangar next to my airplane like that one is though.. Oh.....and I would have to remove most of those gauges.....I would get confused looking at that many gauges..

Mike

 

[Uncle Pug]

.... From your handle *Aviatrr* and location *Florida* I thought there might be a possibility that you were in for a personal bruising when Omar got around to posting...

 

[oxyhacker]

Airspeed Press has such a book in the works but it won't be out for a while. The latest OXY HACKER has expanded the material on filters and continuous mixers, and we continue to add updates on our webpage.

PP mixing is far from obsolete. It's the only way to mix if you don't have your own compressor, and a great way to learn get your feet wet mixing. $200-$300 of hardware and tank leases will get you going, and most of that will still be useful should you get a compressor and move on to continuous mixing. However, I really believe that PP mixing is for us garage mixers and the state of the art has reached a point where any shop that is serious about nitrox really ought to go with continuous mixing or membrane separation.

Continuous mixers work fine for trimix - you just have to add a tee or another port for the He. Only problem is, you really ought to have an He analyzer which adds another $1000 to the tab, although there are ways around this for the bold. While storage banks are nice (but only if you have a adequate compressor - trying to fill a row of 300's in one sitting can really put a strain on a small splash-lubed compressor) you don't really need them, you can fill directly into the tanks though a bit of extra filtration is a real good idea with many small compressors.

BTW, the compressor/mini-cascade/cont mixer shown in the Gallery on the Airspeed website
http://www.airspeedpress.com/gallery.html
cost under $1300 (of which $900 was the used Coltri) including (homemade) hyper filter, mixer and O2 analyzer. Ok, the tanks were scrounged, and a better compressor would be nice, but still shows what can be done if you don't goldplate.

Originally posted by Windknot
Why dont you two get together and write a primer on home fill stations and fill banks.

I've read the Oxygen Hacker, but with the advent of home made nitrox sticks for preblending EAN (and did I understand that the same can be used for Helium as well?) will those make the idea of partial pressure blending obsolete? That is...given one's desire to invest the money and time to purchase quality compressors, storage tanks for the banks etc?
WK

 

[Windknot]

My comments were not intended to claim that the days of PP blending were numbered. I attempted (after the fact in the following sentence) to include an addendum:

"That is...given one's desire to invest the money and time to purchase quality compressors, storage tanks for the banks etc?"

My thinking was along this line.....(I am including myself in the following generalization) As divers, it seems kind of silly that we balk at the price of a good quality compressor, filters, mixers etc. to build and maintain our own fill stations when we obsessively spend money on all of our other equipment that we purchase. PP Blending is the obvious first step.

On the other hand, given the relative ease of constructing blenders, scrounging used tanks for storage banks, used compressors etc, the actual costs of costructing a fill station seem miniscule in comparison to other equipment (my dry suit @ $2,000.00 for example).


One final Kiss up thought....LOVED THE BOOK!!!!!! I go to bed with visions of sugar plums and Oxygen analyzers dancing through my head!!!

Sign me up for the new book as soon as it comes out.

WK