crazy people!

[Turnup]

Nitrogen at higher percentages will suffocate you. This is what happens to people at altitude where the air is described as thin due to the lower percentage of oxygen and higher percentage of nitrogen. Nitrogen is used in tyres due to it being more temperature stable. It has a much lower expansion rate than air as it is heated.

Not so. The coefficient of expansion of all gasses is the same provided that the gas is not at a pressure or temperature close to a phase change (condense, evaporate, or solidify). This is easily verified using google.

There is some controversy over the use of Nitrogen in tyres and I have not been able to find any satisfactory explanation other than for tyres used in extreme conditions. Aircraft tyres run at typically 200 psi and at that pressure oxygen becomes much more reactive - this might also be the case for truck tyres. For car tyres = snake oil.

Racing car tyres run at very low pressures and I have been unable to understand why they use N - even the thermal conductivity of N and air are very nearly the same. It may be that they have always done it this way.

[krisko]

If you have a 15L 300bar cylinder it will have 300x15=4500Liters of air in it (or Nitrogen be it)

a very small room of for example 3mx2mx2ms will have 12000 liters of Air in it. You see the difference in numbers? It gives you the idea.


Even if you dump a full cylinder of Nitrogen into it, will still not kill you. Nitrogen will displace the oxygen yes, if you travel in lift with liquid nitrogen container that is not safe really
But normal room size is OK. You get it.

i can recommend Nitrogen, very dry. lolIt still escapes me why people mess around with compressors these days.

[Scubashot]

If you have a 15L 300bar cylinder it will have 300x15=4500Liters of air in it (or Nitrogen be it)

a very small room of for example 3mx2mx2ms will have 12000 liters of Air in it. You see the difference in numbers? It gives you the idea.


Even if you dump a full cylinder of Nitrogen into it, will still not kill you. Nitrogen will displace the oxygen yes, if you travel in lift with liquid nitrogen container that is not safe really
But normal room size is OK. You get it.

i can recommend Nitrogen, very dry. lolIt still escapes me why people mess around with compressors these days.

As far as I am aware the largest available 300 bar scuba cylinder is only 12 litres, which does still contain more gas than a 232 bar, 15 litre cylinder.

I am not sure how compressed nitrogen gas is produced commercially but I would imagine that compressors are involved at some point.
We certainly use molecular filters with some dive compressors to reduce the nitrogen content of our breathing gas. It is an alternative method of producing enriched air (nitrox), rather than putting a specified pressure of pure oxygen into a tank before topping off to the required pressure with air.

As long as appropriate water filters are incorporated into the compressor then air is certainly dry enough for use in any air gun. It is also widely and cheaply available from many different outlets.

[DedIdick]

As far as I am aware the largest available 300 bar scuba cylinder is only 12 litres, which does still contain more gas than a 232 bar, 15 litre cylinder.

I am not sure how compressed nitrogen gas is produced commercially but I would imagine that compressors are involved at some point.
We certainly use molecular filters with some dive compressors to reduce the nitrogen content of our breathing gas. It is an alternative method of producing enriched air (nitrox), rather than putting a specified pressure of pure oxygen into a tank before topping off to the required pressure with air.

As long as appropriate water filters are incorporated into the compressor then air is certainly dry enough for use in any air gun. It is also widely and cheaply available from many different outlets.

Air through a Molecular sieve and recip compressors to get whatever pressure you're wanting.

http://www.nitrogen-generators.com/n...-how-it-works/

[Scubashot]

Air through a Molecular sieve and recip compressors to get whatever pressure you're wanting.

Yes, I suspected as much, so it looks like people will continue to "mess around with compressors" whether to compress air or extract the nitrogen and compress that!

[robinghewitt]

If I ever want to off myself then it's nitrogen for me. The thing that makes the nitrogen leak so dangerous is that you don't realise you are dying. It is like turning off the oxygen on a rebreather, you just fade away. This was demonstrated on TV by Jonathan Miller, in the days before political correctness, so we would all know how to off ourselves painlessly. Be sure to leave a note on the door.

I use it for the plasma cutter because it is dry, something that plasma cutters really seem to appreciate for some reason known only to plasma cutters and plasma cutter geeks. Perhaps air guns would also prefer dry? It is also very cheap

[Scubashot]

If I ever want to off myself then it's nitrogen for me. The thing that makes the nitrogen leak so dangerous is that you don't realise you are dying. It is like turning off the oxygen on a rebreather, you just fade away. This was demonstrated on TV by Jonathan Miller, in the days before political correctness, so we would all know how to off ourselves painlessly. Be sure to leave a note on the door.

I use it for the plasma cutter because it is dry, something that plasma cutters really seem to appreciate for some reason known only to plasma cutters and plasma cutter geeks. Perhaps air guns would also prefer dry? It is also very cheap

I guess the "dryness" is a feature of the molecular sieve removing the H2O molecules as well as the O2 etc. Certainly dry air is preferable for anything mechanical and metal working at fine tolerances, like scuba regulators and PCP airguns.
Even well maintained diving compressors leave the air dry enough to cause students to complain of dry mouths and dehydration induced cramps as they inhale dry air and exhale moist.
Funnily enough, that is another of the advantages of rebreathers: you get to inhale warm moist air as a by-product of the chemical reaction of the CO2 scrubber unit.

[krisko]

As far as I am aware the largest available 300 bar scuba cylinder is only 12 litres, which does still contain more gas than a 232 bar, 15 litre cylinder.

I am not sure how compressed nitrogen gas is produced commercially but I would imagine that compressors are involved at some point.
We certainly use molecular filters with some dive compressors to reduce the nitrogen content of our breathing gas. It is an alternative method of producing enriched air (nitrox), rather than putting a specified pressure of pure oxygen into a tank before topping off to the required pressure with air.

As long as appropriate water filters are incorporated into the compressor then air is certainly dry enough for use in any air gun. It is also widely and cheaply available from many different outlets.

on large scale they do it by cooling air until it liquifies, then they warm it up and distill its fractions/components. On small scale yes you can have a nitrogen generator/which uses compressors with membranes
(usually there are 2-3 compressors in the unit, which are likely to fail and if one failes, the other 2 keep it going for a while.) compressors all fail if not maintained often. Expensive. yes the water will condense out in the process so if you lead it out, the end product is drier than the ambient air. the inline filtering is a futile process the filter medium saturates fast, you will have to mess around with the desiccant way too often.

...my example with the 15L bottle was the unrealistic large N2 bottle versus a very small room, i would say you could get a headache from it max. If any at all. Dont do it in the cupboard, with the doors shut behihnd you. lol
If you have a large man size bottle, yes have it somewhere where it is not fully enclosed. With good ventilation. Commons sense.

I am not saying scuba air is bad, but i would not recommend steering clear of any compressors. Too much wear and tear and high costs. I am also a scuba diver, these two hobbies go well along. True.

[angrybear]

on large scale they do it by cooling air until it liquifies, then they warm it up and distill its fractions/components. On small scale yes you can have a nitrogen generator/which uses compressors with membranes
(usually there are 2-3 compressors in the unit, which are likely to fail and if one failes, the other 2 keep it going for a while.) compressors all fail if not maintained often. Expensive. yes the water will condense out in the process so if you lead it out, the end product is drier than the ambient air. the inline filtering is a futile process the filter medium saturates fast, you will have to mess around with the desiccant way too often.

...my example with the 15L bottle was the unrealistic large N2 bottle versus a very small room, i would say you could get a headache from it max. If any at all. Dont do it in the cupboard, with the doors shut behihnd you. lol
If you have a large man size bottle, yes have it somewhere where it is not fully enclosed. With good ventilation. Commons sense.

I am not saying scuba air is bad, but i would not recommend steering clear of any compressors. Too much wear and tear and high costs. I am also a scuba diver, these two hobbies go well along. True.

Well almost, "Air" doesn't liquefy, but the two major components Nitrogen & Oxygen do, so in simple terms you make compressed air work very hard & the only energy it can use to do that work is heat energy so it cools & eventually you "cold distil" the two liquids off & store them in insulated tanks.
Cylinders are then filled by allowing the liquid to warm & "gassing off"

At least that's how the RAF plants worked.

[krisko]

sorry, if you take away heat from a gas, in my vocabulary it is called cooling.

The gas will condense first i.e. turns into liquid, if you continue to cool it lower, it will turn into solid. If there are more components of course these will happen at different temperatures. Helium will freeze all gases to solid, that's why it is difficult to handle, more difficult than liquid nitrogen.
Angrybear are you saying that it is not cooling, I am not exactly familiar with how the process itself is done so the air does Liquefy. They compress it, dissipate the heat produced, then expand it to release its stored energy further.

In the end it is still freaking COOLING AND LIQUEFYING. The fridge works similarly, you compress a medium with some heat exchange and expand it in the place where you want the cooling effect no?

by the way N2 and O2 can be called waste/by-products of rare gas production process, if you want to know it really.

https://en.wikipedia.org/wiki/Noble_gas

EDIT: https://en.wikipedia.org/wiki/Air_separation

[angrybear]

sorry, if you take away heat from a gas, in my vocabulary it is called cooling.

The gas will condense first i.e. turns into liquid, if you continue to cool it lower, it will turn into solid. If there are more components of course these will happen at different temperatures. Helium will freeze all gases to solid, that's why it is difficult to handle, more difficult than liquid nitrogen.
Angrybear are you saying that it is not cooling, I am not exactly familiar with how the process itself is done so the air does Liquefy. They compress it, dissipate the heat produced, then expand it to release its stored energy further.

In the end it is still freaking COOLING AND LIQUEFYING. The fridge works similarly, you compress a medium with some heat exchange and expand it in the place where you want the cooling effect no?

by the way N2 and O2 can be called waste/by-products of rare gas production process, if you want to know it really.

https://en.wikipedia.org/wiki/Noble_gas

NO, I was just clarifying that "Air" which is a mixture of gases does not liquefy & then get warmed to distil it's component gases, as you stated .

The individual component gases liquefy at different temperatures and are separated off as they cool, they're then purified & stored as a liquid until required, at least that's how I did it between 93-99

No need to get so touchy over a minor correction, .

[Rob Edge]

Not so. The coefficient of expansion of all gasses is the same provided that the gas is not at a pressure or temperature close to a phase change (condense, evaporate, or solidify). This is easily verified using google.

There is some controversy over the use of Nitrogen in tyres and I have not been able to find any satisfactory explanation other than for tyres used in extreme conditions. Aircraft tyres run at typically 200 psi and at that pressure oxygen becomes much more reactive - this might also be the case for truck tyres. For car tyres = snake oil.

Racing car tyres run at very low pressures and I have been unable to understand why they use N - even the thermal conductivity of N and air are very nearly the same. It may be that they have always done it this way.

That was the way that Michelin explained it be it right or wrong in the terms of physics.