How do you make oxygen clean air?

[CAPTAIN SINBAD]

Hello:

I am daydreaming about buying a small portable compressor to drive around and dive remote locations. Problem is ... how do you make air which can be clean enough for a tank also being used for nitrox? Does O2 clean air require a special type of compressor?

Thanks -

 

[Superlyte27]

If I understand what you're asking.... How do you make a compressor blow air clean enough to make nitrox with?

You use good filters between the compressor and the cylinder. Compressor matters little, filters matter alot.

 

[Wookie]

If I understand what you're asking.... How do you make a compressor blow air clean enough to make nitrox with?

You use good filters between the compressor and the cylinder. Compressor matters little, filters matter alot.

I think that I don't agree, but I may be wrong. I use standard Mako 1803 filters and I test for OCA every time. I don't use hyper filters. I am meticulous about maintenance of my compressors, as well as using proper oil. So, I think that I think that the filter matters little, and the compressor matters a lot.

I could be convinced otherwise by a compressor guru, however.

Regardless, Captain Sinbad, any compressor with a hyper filter will make OCA.

 

[Superlyte27]

used 1000 dollar compressor or brand new 25cfm 20,000 dollar compressor, doesn't matter which, as long as they are both maintained properly, you can get the same quality of air from both. All it takes is the right filter.

 

[CAPTAIN SINBAD]

I am not sure if (with my limited knowledge of tanks fills) I am asking the right question so let me explain what happened:

I wanted to buy a couple of steel tanks. I asked the dive shop what tank would they recommend to switch between both air and nitrox. The guy said the tank would have to be filled with O2 compatible air. He also said that while most dive shops that fill nitrox, also have 02 compatible air, some shops may not. If that non-O2 compatible air gets in the tank it will require 02 cleaning for nitrox use. Thus if the same tank is to be used for nitrox as well as air then I have to make sure that air is O2 compatible air. From what I understood, it meant a cleaner / more purified air??? The question that pops in my mind is that if I was to purchase a portable compressor, the air that will go in my tank must not make it incompatible with nitrox. Would any compressor do or do I need to buy an attachment or gizmo that would make my air 02 compatible?

Hope this makes sense.

Thanks.

 

[Mark Michaud SELAUSAR]

First I think you need a new dive shop. Either they are gonna make bank on you for unnecessary VIP's, or they don't understand nitrox. 1. If they are partial pressure blending each tank, your tank does need to be clean, no argument there. 2. If they blend into storage bottles (banks) pure O2 is not going into the tank and the O2 explosion hazard is pretty insignificant. 3. Any shop that sells breathing gas (air, Nitrox, trimix, etc) is required by law to test their gas quarterly. Some don't so you should always ask to see their results if in an unfamiliar shop and do not know if they are compliant. As long as they are compliant they should be pumping safe air out of the compressor, but remember, it is up to you to personally test the mix, check for CO (carbon Monoxide) and for any funny odors, which should not be there. You should be able to put nitrox in a bottle, then air, then nitrox if you wish to do so, without any safety issues. That is the reality of it as far as banked nitrox goes. As long as your bottle is not empty and water gets in, it is as clean as it was when the valve was tightened. Shops can not pump dirty gas, practically and legally. Of course they can but, if they do, people will be harmed and that is bad for business. Breathing gas is either clean or not. Air (21%) or Nitrox, it doesn't matter. The compressor is either pumping clean air or dirty air. Most shops in my area, and our local fire district, keep their banks at Grade E breathing air which is high quality. Most shops follow that standard, but again, you should ask and look at the certificate. Most shops are very proud to show you their certificate.

As far as owning your own compressor, make sure you research this matter. You need to make sure you are not picking up moisture, CO from engines, smokers, etc, and that it is seriously maintained........plus a bunch of other stuff. You may save a bunch of money by adding more bottles and don;t even worry about the compressor. Crunch the numbers and ask people who have their own and have owned one for several years. FWIW

I hope this didn't come across as if I were talking down to you. That was not my intent. I wanted to get some basics as if you may not have heard them yet, or to reinforce a class that provides a lot of info in a short time. This is a fun sport and it needs to stay that way. You seem to be very motivated and feel you are looking for straight and good information. Good Luck. Mark

 

[Jxh2297]

First I think you need a new dive shop. Either they are gonna make bank on you for unnecessary VIP's, or they don't understand nitrox. 1. If they are partial pressure blending each tank, your tank does need to be clean, no argument there. 2. If they blend into storage bottles (banks) pure O2 is not going into the tank and the O2 explosion hazard is pretty insignificant. 3. Any shop that sells breathing gas (air, Nitrox, trimix, etc) is required by law to test their gas quarterly. Some don't so you should always ask to see their results if in an unfamiliar shop and do not know if they are compliant. As long as they are compliant they should be pumping safe air out of the compressor, but remember, it is up to you to personally test the mix, check for CO (carbon Monoxide) and for any funny odors, which should not be there. You should be able to put nitrox in a bottle, then air, then nitrox if you wish to do so, without any safety issues. That is the reality of it as far as banked nitrox goes. As long as your bottle is not empty and water gets in, it is as clean as it was when the valve was tightened. Shops can not pump dirty gas, practically and legally. Of course they can but, if they do, people will be harmed and that is bad for business. Breathing gas is either clean or not. Air (21%) or Nitrox, it doesn't matter. The compressor is either pumping clean air or dirty air. Most shops in my area, and our local fire district, keep their banks at Grade E breathing air which is high quality. Most shops follow that standard, but again, you should ask and look at the certificate. Most shops are very proud to show you their certificate.

As far as owning your own compressor, make sure you research this matter. You need to make sure you are not picking up moisture, CO from engines, smokers, etc, and that it is seriously maintained........plus a bunch of other stuff. You may save a bunch of money by adding more bottles and don;t even worry about the compressor. Crunch the numbers and ask people who have their own and have owned one for several years. FWIW

I hope this didn't come across as if I were talking down to you. That was not my intent. I wanted to get some basics as if you may not have heard them yet, or to reinforce a class that provides a lot of info in a short time. This is a fun sport and it needs to stay that way. You seem to be very motivated and feel you are looking for straight and good information. Good Luck. Mark

Well you are correct on the partial pressure vs banked gas argument. If he was wanting higher than 40% it wouldn't matter if it was banked or partial pressure blended. He would need o2 compatible tank.

 

[Wookie]

I'm going to let you in on a clean little secret. The term Oxygen Compatible Air is a term and a standard made up by a SCUBA training organization in 1990. It's a gimmick, much like annual VIP's of cylinders that the scuba industry loves to hold up and tout as being all about safety. And, to be fair, in many cases, the safety is warranted and reasonable. It is also a way for a dive shop to make a buck or 2. If you bring a cylinder in for a fill, the tank monkey looks at the side of it and sees that your "VIP sticker" has expired. Now, he gets to charge you $30 to put a new sticker on the tank. Same with OCA. You go in for a nitrox fill. The tank monkey asks if you have filled your cylinder only with OCA. No, you sheepishly reply, I got this one fill..... The tank monkey smiles because now he's got you for an $80 O2 cleaning fee.

That's not to say that the VIP program and the OCA standard are worthless. I've seen some compressor systems in use every day that would make you swear off diving. MOST providers of compressed breathing air are responsible, reliable, and really trying to do the right thing. BUT-there are those out there that will contaminate the inside of your cylinder. Not maintaining your cylinder with OCA gas exclusively will not necessarily mean your cylinder isn't O2 clean. Take a course in cylinder cleaning and inspection, and you'll be able to certify your own cylinders O2 clean. There is a compressor guy here on this board (I think he is in Kentucky) who will sell you a little 2 CFM portable that will work for you just fine in remote locations. Put a hyper-filter on it and have a ball.

To let you in on the dirty part of the secret. We (folks who own compressors and sell the air to the public) test and test and maintain our compressors and do our best to provide quality breathing gas. The test is really only good while the system has the same components that it was tested with. What I mean by that is that as soon as you replace a component of the system, the previous test is no good. I replace my filters every 65 hours of operation. That may be 3 times on a 10 day dive trip. every time I replace a filter, I stand the chance of rolling an o-ring (I've done that), or incorrectly installing a filter (I've done that), or of failing to replace the components correctly I've never done that), or any number of other things that render the test for OCA useless. The feds require a bi-annual air test, and the State of Florida currently requires one every 3 months (that requirement is about to end) because it is the best system we have, but it is by no means a guarantee that the fill you get tomorrow won't kill you.

Have fun with it.

 

[Mark Michaud SELAUSAR]

Well you are correct on the partial pressure vs banked gas argument. If he was wanting higher than 40% it wouldn't matter if it was banked or partial pressure blended. He would need o2 compatible tank.

You could be correct. But, as a discussion such as this for a person who seems to be a new diver based on his profile stats, I am not gonna be politically correct and try to cover every little things and issue. The 2 most common mixes used in recreational diving are 32% and 36%. I also make the assumption that he has taken a class in nitrox. The OP seems to be trying to get things sorted out and is looking for practical advice. He is getting it.

 

[mikecotrone]

First I think you need a new dive shop. Either they are gonna make bank on you for unnecessary VIP's, or they don't understand nitrox. 1. If they are partial pressure blending each tank, your tank does need to be clean, no argument there. 2. If they blend into storage bottles (banks) pure O2 is not going into the tank and the O2 explosion hazard is pretty insignificant. 3. Any shop that sells breathing gas (air, Nitrox, trimix, etc) is required by law to test their gas quarterly. Some don't so you should always ask to see their results if in an unfamiliar shop and do not know if they are compliant. As long as they are compliant they should be pumping safe air out of the compressor, but remember, it is up to you to personally test the mix, check for CO (carbon Monoxide) and for any funny odors, which should not be there. You should be able to put nitrox in a bottle, then air, then nitrox if you wish to do so, without any safety issues. That is the reality of it as far as banked nitrox goes. As long as your bottle is not empty and water gets in, it is as clean as it was when the valve was tightened. Shops can not pump dirty gas, practically and legally. Of course they can but, if they do, people will be harmed and that is bad for business. Breathing gas is either clean or not. Air (21%) or Nitrox, it doesn't matter. The compressor is either pumping clean air or dirty air. Most shops in my area, and our local fire district, keep their banks at Grade E breathing air which is high quality. Most shops follow that standard, but again, you should ask and look at the certificate. Most shops are very proud to show you their certificate.

As far as owning your own compressor, make sure you research this matter. You need to make sure you are not picking up moisture, CO from engines, smokers, etc, and that it is seriously maintained........plus a bunch of other stuff. You may save a bunch of money by adding more bottles and don;t even worry about the compressor. Crunch the numbers and ask people who have their own and have owned one for several years. FWIW

I hope this didn't come across as if I were talking down to you. That was not my intent. I wanted to get some basics as if you may not have heard them yet, or to reinforce a class that provides a lot of info in a short time. This is a fun sport and it needs to stay that way. You seem to be very motivated and feel you are looking for straight and good information. Good Luck. Mark

I am attaching two Gas Sample analysis that I have performed recently to show you the specifications of "CGA Grade E" air and IANDT OCA air. Notice the difference's between Grade E and OCA in the "Specification Allowable Limits". This gas analysis would be done each quarter as discussed in this thread.

HTH