where is nitrox $30 a fill?
O2 cleaning question
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where is nitrox $30 a fill?
In basic terms -"oxygen clean" means that the equipment (tank or whatever) is cleaned to a standard which minimises the risk of a spontaneous explosion (aka deflagration - an uncontrollable fire) due to gas under high pressure impacting materials or particles in the system which present a risk of combustion.
The act of compressing gas heats the gas - and vice versa - decompressing gas cools the system down (the term is diabatic de/compression). High pressure 02 cannot combust by itself but it provides a vector for combustion, and under pressure generates a great deal of heat - heat + 02 + combustible material = fire
Firstly - the materials used in a tank which is required to hold pure 02 must be "compatible" with high pressure 02 - i.e., material produced without the use of petrochemicals or other ignitable compounds - viton and teflon being brand names we hear (viton o-rings, teflon lined tubes) - even these will burn at very high temperatures, but significantly reduce the risk of fire over your ordinary o-ring.
O2 clean means removing any trace elements of hydrocarbons and other materials (even the grease from a human fingerprint), which might ignite in a high pressure 02 environment.
When it comes to the quality of the air being put into a nitrox tank, there are international standards for "breathable" gas which limit the amount of hydrocarbons or other pollutants in the gas to a level that is safe for human consumption. Hence the need for a filtration system on the air compressor used to pump your tanks. Beyond health concerns, "02 clean air" must be filtered to a point where the risk of unburned hydrocarbons is reduced to a level which minimises the risk of these particles spontaneously igniting in a high pressure 02 environment.
As previously mentioned - partial pressure filling means that a tank is pumped with pure 02 then topped up with air - in which case the system must be both 02 compatible and 02 clean. With bank (premixed) or membrane filling, the mixture pumped into the tank (say 32%) is highly unlikely to be rich enough to combust. As you will learn in the nitrox course, anything 40% or below is treated as regular air when it comes to safety concerns, and anything over 40% is treated as pure 02.
So - if you fill an 02-clean/compatible tank with air from a regular compressor that does not have the extra filtration system in place, you make the tank "unclean". If you use "02 clean/compatible" filtered 21% air, it's not a problem.
The actual partial pressure of a gas underwater after the tank is filled is immaterial - it's the filling process that is the main hazard.
Hope that answers a few questions.
Cheers
C.
PS - nitrox at my dive centre is free, free, free!
The act of compressing gas heats the gas - and vice versa - decompressing gas cools the system down (the term is diabatic de/compression). High pressure 02 cannot combust by itself but it provides a vector for combustion, and under pressure generates a great deal of heat - heat + 02 + combustible material = fire
Firstly - the materials used in a tank which is required to hold pure 02 must be "compatible" with high pressure 02 - i.e., material produced without the use of petrochemicals or other ignitable compounds - viton and teflon being brand names we hear (viton o-rings, teflon lined tubes) - even these will burn at very high temperatures, but significantly reduce the risk of fire over your ordinary o-ring.
O2 clean means removing any trace elements of hydrocarbons and other materials (even the grease from a human fingerprint), which might ignite in a high pressure 02 environment.
When it comes to the quality of the air being put into a nitrox tank, there are international standards for "breathable" gas which limit the amount of hydrocarbons or other pollutants in the gas to a level that is safe for human consumption. Hence the need for a filtration system on the air compressor used to pump your tanks. Beyond health concerns, "02 clean air" must be filtered to a point where the risk of unburned hydrocarbons is reduced to a level which minimises the risk of these particles spontaneously igniting in a high pressure 02 environment.
As previously mentioned - partial pressure filling means that a tank is pumped with pure 02 then topped up with air - in which case the system must be both 02 compatible and 02 clean. With bank (premixed) or membrane filling, the mixture pumped into the tank (say 32%) is highly unlikely to be rich enough to combust. As you will learn in the nitrox course, anything 40% or below is treated as regular air when it comes to safety concerns, and anything over 40% is treated as pure 02.
So - if you fill an 02-clean/compatible tank with air from a regular compressor that does not have the extra filtration system in place, you make the tank "unclean". If you use "02 clean/compatible" filtered 21% air, it's not a problem.
The actual partial pressure of a gas underwater after the tank is filled is immaterial - it's the filling process that is the main hazard.
Hope that answers a few questions.
Cheers
C.
PS - nitrox at my dive centre is free, free, free!
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Thanks Crowley top notch answer. As for that "extra filtration system in place" do all dive shops have this in place on there compressors?? Is that standard or just for O2(nitrox) fills? Besides it called the "extra filtration system" is there a proper name for it?
I know all compressors have filtration systems I am just getting to the nit and gritty about it I guess.
Thanks
I know all compressors have filtration systems I am just getting to the nit and gritty about it I guess.
Thanks
That is totally weak. Like diving don't cost enough already.
Yep. In fact I think I paid $35 extra to use EAN36 when diving the ex-HMAS Brisbane last month... My buddy and I did 4 dives over 2 days, so there's $280 for gas alone, on top of the dive/boat fees which were $640 all up. And we had our own gear apart from tanks. SO including petrol for the drive it was about $500 each for 4 dives. No wonder I don't dive in Australia much - I could do a week of diving in the Philippines for the same price
Still, at least it's not helium
Still, at least it's not helium
fire_diver
Contributor
Not, not all compressor systems have the extra filtration to create "oxygen clean air". Filter media and cartridges are expensive and have to be replaced often. Shops won't pay for it if it's not absolutely needed.
Many shops move to banking premixed nitrox to avoid the extra expenses, as well getting the most use for an oxygen cylinder.
I work in a very busy resort type place and the cost of filling a tank with either air or 32% is relatively meaningless - the tank station operates a membrane system (which basically filters Nitrogen out of the air), so we don't have to worry about the expense of 02 clean tanks and they basically push a button which reads 21% / 32 %. For the diving we do here it doesn't matter so much. Accurate blends for tec diving or nitrox on request carry a premium of course, but the actual work involved does not warrant any surcharge for basic recreational diving.
Going back a few years ago to my job in Thailand, it would take me a whole day with a partial pressure blending system to mix 16 accurately blended tanks, and I could maybe make 5 sets of trimix doubles in a day given the equipment I had to work with - and for sure, I'm sorry, you're going to pay me for that because that's a whole day's work to mix enough tanks for one dive.
Depends on the circumstances and the environment in which you dive. I don't mix tanks here but it literally is the press of a button or the twiddle of a dial to change from one blend to another, and charging for that would make all concerned feel a bit guilty, to be honest.
Swings and roundabouts - the initial investment in a membrane system can be significant, but if you're pumping out 200 tanks per day it's immaterial - on the other hand if you have to pay somebody to mix gas with a partial pressure system you have to pay for the delivery of 02, the time it takes to mix and the overhead involved in the fact that sometimes, it all goes wrong and you have to start again.
If you throw helium into the mix - which is generally expensive - then you pay for that also.
With the filtration system - another overhead. For a standard air compressor, we re-built the filters by hand; it's quite simple. The clean air filters for nitrox / trimix gas blending we bought, disposed of and replaced, because the standards for clean air are that much higher.
Talk to the people who mix your gas - it is dependent on volume of custom to a large extent, and extra fees for nitrox can not necessarily be regarded as LDS rip-offs - it depends on the way you do it, and the general requirement for it.
Cleaning a tank to 02 standards is a BITCH - and if you accidentally sneeze on a component during cleaning you have to start all over - so do not begrudge the mixers if they charge you for it. Inspecting valves in cotton gloves under ultraviolet light, cleaning them with various solvents and an ultrasound bath takes time, money, and diligence, so the cost of this varies. In my current job, as I say, the extra cost is meaningless, but for a small dive centre that has to go through this process, it can cost a lot of money.
Seek answers before you ask questions.
Best regards
C.
Going back a few years ago to my job in Thailand, it would take me a whole day with a partial pressure blending system to mix 16 accurately blended tanks, and I could maybe make 5 sets of trimix doubles in a day given the equipment I had to work with - and for sure, I'm sorry, you're going to pay me for that because that's a whole day's work to mix enough tanks for one dive.
Depends on the circumstances and the environment in which you dive. I don't mix tanks here but it literally is the press of a button or the twiddle of a dial to change from one blend to another, and charging for that would make all concerned feel a bit guilty, to be honest.
Swings and roundabouts - the initial investment in a membrane system can be significant, but if you're pumping out 200 tanks per day it's immaterial - on the other hand if you have to pay somebody to mix gas with a partial pressure system you have to pay for the delivery of 02, the time it takes to mix and the overhead involved in the fact that sometimes, it all goes wrong and you have to start again.
If you throw helium into the mix - which is generally expensive - then you pay for that also.
With the filtration system - another overhead. For a standard air compressor, we re-built the filters by hand; it's quite simple. The clean air filters for nitrox / trimix gas blending we bought, disposed of and replaced, because the standards for clean air are that much higher.
Talk to the people who mix your gas - it is dependent on volume of custom to a large extent, and extra fees for nitrox can not necessarily be regarded as LDS rip-offs - it depends on the way you do it, and the general requirement for it.
Cleaning a tank to 02 standards is a BITCH - and if you accidentally sneeze on a component during cleaning you have to start all over - so do not begrudge the mixers if they charge you for it. Inspecting valves in cotton gloves under ultraviolet light, cleaning them with various solvents and an ultrasound bath takes time, money, and diligence, so the cost of this varies. In my current job, as I say, the extra cost is meaningless, but for a small dive centre that has to go through this process, it can cost a lot of money.
Seek answers before you ask questions.
Best regards
C.
I don't know if this is directed at the post I made or not - I was merely observing that it was a significant additional cost; I paid it without comment, and would do so again (probably will do the same dives next year)
As to whether it's an appropriate charge for filling their own dedicated nitrox tanks with banked EAN36, don't know, don't care
I saw the question of ow to tell O2 clean air. You should ask to see the most recent test data for the shops air. Good shops usually test it quarterly and at least anually. The test should be certification to"Class E" Air to be O2 Clean. I think Class D is suitable for humans and Class E is a lower hydrocarbon content.
DP
DP
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