crazy people!

[wiggers]

My work is the biggest consumer of liquid nitrogen in the country.
It's bloody cold at -196 degrees C and 1 litre expands to 694 litres of gas.

Glad I got that off my chest :-)

[aris]

There was A YouTube video where someone filled with helium. https://youtu.be/zXajYpk3gRU

Velocity up a little bit.

[tinbum]

The range of gasses that could be tried is quite large, many are inert, but some are plenty nert!

The best and only advice must be "breathing air only" to avoid confusion.

[zephyr]

Combustion requires the correct ratios of ‘fuel’ and oxygen, by using nitrogen that ratio is managed. Hence why nitrogen is sometimes used for:
a) drilling hydrocarbon (oil/gas) wells
b) fire extinguishant

The ‘BOOM’ comment isn’t completely wrong. While the ‘explosion’ won’t be caused by combustion, there could be a catastrophic mechanical failure of the pressure vessel if liquid nitrogen is allowed to warm and become nitrogen gas - the pressure would massively increase. But we aren’t talking of liquid nitrogen, are we?

The unwanted characteristics of nitrogen are, as said before, the potential for asphyxiation (although extreme cold is associated with liquid nitrogen) in addition there can be damage to some of the materials used in seals. Nitrogen molecules are much smaller than oxygen molecules and can get ‘inside’ the material of the seals. This results in (1) a very slow (insignificant) loss of pressure, (2) failure of the seals if there is rapid depressurisation.

To give some perspective of the dangers of nitrogen and the effect of the nitrogen molecule being smaller - ever wondered why crisp bags went from being transparent plastic to the silvery material used today? It’s because the gas inside the bag is nitrogen (no water moisture, as said before), which will leak through the transparent plastic!

[angrybear]

My work is the biggest consumer of liquid nitrogen in the country.
It's bloody cold at -196 degrees C and 1 litre expands to 694 litres of gas.

Glad I got that off my chest :-)

Whilst in the RAF I was Q LOX/LIN production, good fun but LOX is not to be treated lightly.

[ChrisC]

Whilst in the RAF I was Q LOX/LIN production, good fun but LOX is not to be treated lightly.

We used to fill the LOX pots for the Dominie's.

[Shedder]

My recollection is that the air we breathe is 80% nitrogen, so it isn't very dangerous as a gas.

[Rob Edge]

My recollection is that the air we breathe is 80% nitrogen, so it isn't very dangerous as a gas.

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.

[sevorg]

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.

Is the ratio of nitrogen to oxygen different at altitude? I thought the problem at high altitude was simply less oxygen (and less nitrogen) due to less air in a given volume (lower density)

[Rob Edge]

Is the ratio of nitrogen to oxygen different at altitude? I thought the problem at high altitude was simply less oxygen (and less nitrogen) due to less air in a given volume (lower density)

Try here https://www.higherpeak.com/altitudechart.html

[Scubashot]

Is the ratio of nitrogen to oxygen different at altitude? I thought the problem at high altitude was simply less oxygen (and less nitrogen) due to less air in a given volume (lower density)

The ratio remains the same but the problem arises due to the physics of partial pressures.
At 1 atmosphere there is roughly a partial pressure of 0.21 of oxygen and 0.79 of nitrogen.
At 2 atmospheres (eg 10 metres under water on scuba. 1 ATM of water pressure and the original 1 of air pressure) there is a partial pressure of oxygen of 0.42 and a partial pressure of nitrogen of 1.58.
Conversely at 0.5 atmospheres at altitude the partial pressure drops to 0.105 of oxygen and 0.395 of nitrogen.

The important thing is how the human body reacts to the partial pressures of these gasses. From memory a partial pressure of less than 0.16 of oxygen will result in a loss of consciousness and less than 0.12 may be fatal.
In diving we have to consider that both oxygen toxicity and nitrogen narcosis will occur as the levels rise,. This will result in convulsions and potential drowning from oxygen and irrational behaviour and potential drowning from nitrogen.
To combat these effects we accurately blend gasses to provide the correct partial pressures for the required depth of dive and will switch between different mixes on the descent and ascent.
It may be further complicated by wishing to increase the oxygen content of our decompression gasses to accelerate the process!

Stick to air in your guns, it's far less complicated! :-)

[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.

[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.

[DedIdick]

No boom....

But if your air cylinder leaks under your bed no massive drama.... if your nitrogen cylinder leaks you might not wake up.... ever

My recollection is that the air we breathe is 80% nitrogen, so it isn't very dangerous as a gas.

Correct, so a slightly leaking nitrogen cylinder under your bed should be no problem.

Only play with compressed gases IF you're COMPETENT & know what you're doing!

(So if the guy, talked about in the OP, works with compressed gases & is competent, then HE should have no issues.)