If you were to use a partil pressure system to fill tanks to 100% o2 could you then fill ordinary tanks with the same compressor afterwords. ie what would it take to fill normal tanks with air then to top off other tanks with 100% o2 in it. does the compressor have anything special done to it to top off these high o2 tanks? appreciate being enlightened, thanks,cameron.
Blending pure o2
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Not sure if you are talking about a continuous blending system, but partial-pressure blending does not involve oxygen passing through a compressor. There are compressors designed to compress oxygen specifically. Air compressors used for processing nitrox, can not pump 100% pure oxygen and are generally limited to a max of 40%. "Brave" souls might go higher, but I'll pass.
Craig
Craig
matt t.
Contributor
You want to use a compressor with a "hyper" filter stack for partial pressure filling. It sounds like you need to take an O2 clean and/or blending class.
If you are talking about a Lawrence Factor Hyper-pure, it should not be in-line directly after the compressor. It is designed to be after storage. Most compressors will cycle if they have auto restart should you hook the unit up directly after or if you have auto stop you will be having to restart the compressor during the fill process. The flow restrictor in the hyper-pure is rated based on having a supply pressure of about 3000 psi and a down stream pressure of "0" psi. If the rate is 12 cfm, as down stream pressure builds, that rate will decrease and as you approach equilibrium, it will slow to a trickle.
As an example, if you have a cascade of three banks with one HC4500 storage bottle per bank. With all bottles full and topping off (partial-pressure blending) 4-80's, it will probably take 20-25 minutes to complete the filling process with the twin tower Hyper-pure appliance (20 cfm flow restrictor).
Craig
When partial-pressure blending, you typically decant pure O2 from a supply bottle into the tank, then top off the tank with air from a compressor. So you need to be concerned with the quality of air that you use to top off the O2 (must be OCA). You can put OCA into anything.
Continuous blending up to 40% does not require OCA (according to most), which is when you feed O2 through the compressor via a mixing stick.
"Partial Pressure" filling a tank to 100% O2 is impossible, since we aren't dealing with partial pressures but pure O2. In this case, you would eiter decant the O2 from the supply bottle until the 2 equalize. If you need more pressure, you would then use a booster to increase the pressure of the recipient to a level above the supply bottle.
Hope this clears it up for you.
Continuous blending up to 40% does not require OCA (according to most), which is when you feed O2 through the compressor via a mixing stick.
"Partial Pressure" filling a tank to 100% O2 is impossible, since we aren't dealing with partial pressures but pure O2. In this case, you would eiter decant the O2 from the supply bottle until the 2 equalize. If you need more pressure, you would then use a booster to increase the pressure of the recipient to a level above the supply bottle.
Hope this clears it up for you.
matt t.
Contributor
I think you're over thinking my answer. I don't think the OP is concerned with the mechanics of the filter system. He was asking about partial pressure fills and I gave him an accurate fairly general answer.
Anyone considering this product should be concerned with the mechanics. By context, you were suggesting a "compressor with "hyper" filter stack", which to me indicates a direct hook up. I was merely trying to explain what happens with a system connected in this fashion. Most people considering a Lawrence Factor Hyper-pure unit look at the flow rate and think "Ok, my compressor is 3.5, 6, or 8 cfm, so the "12" cfm appliance will work" and believe they can just hook the appliance directly in line with the compressor standard filtration. I field calls about these units quite often and that is the callers standard thought process.
Provided you are producing Grade "E" air (which is quite acceptable for pp blending), Hyper-pure units are basically a "Safety Device" in case of a problem with the primary filtration. It is stated in the owners manual that Grade "E" must be supplied to the appliance. I'm sure there are those that will debate "E" vs "OCA", but industry standards accept "E". Do I think "OCA" is the safer way to go, Yes. Do I think those that blend with "E" are wrong, NO, as long as that grade of air is maintained.
Craig
caver
Contributor
Cameron,
I believe you are talking about PARTIAL pressure fills not PARTIL. If that is true and if you have any experience at all, you know that you are not going to run 100% O2 through the compressor. You will top the bottles off with air. The air needs to be OXYGEN COMPATIBLE air...I would suggest you take a blending course so you don't kill yourself or someone else.
caver
Contributor
Craig,
When you say "industry standards accept E" ..please give us an example. IANTD, TDI, NOAA, PADI, NAUI, to name a few, all call for OCA when doing PP blending. In 1992 the technical diving training agencies along with several U.S. government agencies meet in Orlando, FL and agreed on a set of standards for OCA. And they agreed on the use of it when blending with O2. Who changed the industry standard?
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pescador775
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1992 was a long time ago. Since then, various definitions of OCA have been offered by separate entities with no industry standing except within SCUBA instruction and govt bureaus, and which have entered into separate documents. These are advisory in nature only unless the compressor operator is employed by NASA, etc. Since then, CGA Grade E, which actually is an industry standard (and not just a guideline or MILSPEC), was upgraded as to water content. The compressor manufacturers responded by tightening up the entire filtration spectrum, and not just for water. Some argue it was the other way around and the CGA was just responding to a reality but let's not digress.... As a result, most air sources labeled as "grade E" are actually pumping air closer to or identical to so-called "modified grade E". This is especially true when air is banked and decanted. Some people in industry know about this, have done the tests, and have come to accept Grade E as "close enough" in practice. The problem comes in when something goes awry and a trickle of bad stuff slips into the air line. Based on this, there are some WAG estimates that 10-15% of SCUBA shops are not pumping oxygen compatible air at some particular time regardless of what it is called. Thus, some opt to secure cover for their operation (CYA) by adding a hyper pure filter of some kind.
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