TargetTalk

So I bought a new car & tires were filled w/nitrogen. We also use it at work quite a bit. So why not fill our tanks up w/it instead of compressed air? It is readily available from a welding store or industrial gas house. It's dryer than air. Any don sides?
thanks

Jay

The biggest issue is that it requires a regulator and custom adapters.

Since "air" is 80% nitrogen anyway, it doesn't matter (and some places do use N for their fill stations) which you use. But it's handy to use SCBA and SCUBA to fill the air rifle/pistol cylinders because they operate at the same pressures. There's no real price benefit to using N, nor availability (there's a fire station in Every community that has a method for refilling their SCBA tanks), so no real reason to use it other than wanting to.

Some people get all up in arms about the 'Factories' specifying 'air', and not wanting to go against the lawyer written manuals. I've personally used both and own a SCUBA tank because it's easier across the board.

Air comes for free if you use an hand pump or a compressor (many club own a compressor) or very cheap (scuba diving shop) and is available everywhere. You can carry your pistol/rifle in an airplane together with a hand pump and are self sufficient.

The drawback is that the pistol/rifle is a little more complicate as it needs a regulator.

CO2 must be bought but the pistol/rifle is simpler, no regulator needed. If you carry your pistol/rifle in an airplane you must find a solution to refill at arrival.

Nitrogen must be bought and needs a regulator just like air. Just like for CO2, if you carry your pistol/rifle in an airplane you must find a solution to refill at arrival.

So, as you can see, Nitrogen combines the drawback of air and CO2 without having the advantages of air or CO2.

Jipe very few clubs in North America have compressors I'd be surprised if I needed the fingers on one hand to count them all. So really Air, Nitrogen or CO2 requires the purchase of said gas unless you plan on using a hand pump.

The answer to the OP's question is you can use nitrogen there's no draw back and no real benefit either. Just make sure the tank is the correct pressure and if not then you have an added expense of a regulator. Most people find SCUBA tanks more convenient in many places in North America. Smaller towns and such Nitrogen might actually be easier to find.

The real benefit of nitrogen is that its 100% dry. Water vapor in air causes its pressure to vary with temperature much more than dry air or nitrogen (because of the partial pressure of the water). In car tires this matters because car tires see wide temperature swings: they heat up a lot after you drive on them for a while. The resulting pressure change for plain, un-dried air can be significant (like 20% or more).

Air used in airguns has usually been dried with a desiccant in the hand pump, or by the air system at the scuba shop. Also, air cylinders on an airgun typically see a relatively constant temperature. This ends up negating the main advantage of using nitrogen over air.

The main advantage of nitrogen in tires is that oxygen degrades (oxidizes) the rubber of the tires from within especially when they get hot. This is not an issue in an aluminum vessel.

Roger

At our shooting club the number of PCP guns grew very much over the last few years, as a lot of shooters went from CO2 and SSP guns to the newer ones, to the point that we in the board felt justified to provide free access to precompressed air at the shooting stand.

At first, we rented a cylinder and took the burden of carrying it to the only source of air at 200 BAR, which was the base of the military divers in a city close to ours, as no one in our city had compressors capable of reaching that pressure. Sport divers do the same with their SCUBA tanks. And we're in a 500,000 people city!!!

It became a worry after a few months, as we had to deliver the cylinder and pick it up two days later, in a truck. So- by mere chance - we happened to meet a purveyor of compressed Nitrogen at 200 BAR. They don´t use that much pressure, as they refill smaller cylinders for hospital use (I believe), so when our weapons are filling below 170 BAR, we tell them, they give us another fully loaded cylinder, take the used one, deduct the Nitrogen used and bills us accordingly, plus a montly rental of about 7 U$D.

The advantage we found was that when using air, we needed a special piece with a male thread the size of the cylinder valve, and a female thread compatible with the adapting pieces each weapon had (We had to had it made from bronze by a machinist). Now, the size of the threaded valve in the N cylinder fits directly in the factory adaptor. I'm not an specialist, but I was told it is due to industrial regulations that mandate such sizes.

Apart from it, nitrogen as commercially sold is cleaner than air and, of course, in case of any accident it is non-flammable (for what it's worth).

Otherwise, we found no functional difference in the performance of our guns, nor there is any reason for them to occur.

No down side actually it is better as it is pure inert gas. If you go to a welding supply vendor you can get a big tank filled to 6000 PSI IIRC they are around 150 cubic feet about 5 feet tall. Needless to say you can get a lot of fills off 6000 PSI and it just costs you the tank rental and fill/refill. For those not near a 4500 or 3000 PSI that shoot a lot and don't want to hand pump it is a very viable option.


Bo

OMRC Nitrogen System

I think the benefit of using N is you do not need a card saying you are a "diver" to get your tank filled. For 5 years I drove by a dive shop which would not fill up my SCUBA tank. I had to ask a friend to fill it up for me or drive 45 mins out of my way to go to another shop who would fill it without being a "diver".

I like the idea of using N. Using a hand pump is easy also.

RandomShotz wrote:The main advantage of nitrogen in tires is that oxygen degrades (oxidizes) the rubber of the tires from within especially when they get hot. This is not an issue in an aluminum vessel.

Actually, I believe that internal corrosion of tanks (aluminium or steel) is an issue especially if water gets in at some stage by way of improperly dried air. Thus using nitrogen would significantly increase the service life of the tank by removing the oxygen. That said, steel scuba tanks already have a service life of 40 odd years whereas ally tanks maybe 15 years before scuba shops start to baulk at re-filling them.

Bob

Its worth remembering Nitrogen leaks can be fatal. Using industrial sized tanks in a closed room without an Oxygen depletion alarm is dangerous since Oxygen can be displaced.

JamesH.

In enclosed environments You're correct. In an old (nearly 100,000 sq ft) Warehouse that was built in 1880, not so much... You could release the Nitrogen full open and it would never displace enough Air to cause the problems you're concerned with. Nitrogen is lighter than air and Our range is more that 26,000 sq feet x 11 foot ceilings. The Tank is Chained to the Wall, and the valve is closed when not actually filling cylinders.

Depends, pure Nitrogen is marginally lighter than 'air', but then cold nitrogen released into warm air can be more dense. And I haven't noticed a layer of pure oxygen forming around my feet due to the density difference.

It was a general warning to those membersof the forum who don't use your range.

The jump of airgun is from movement of pellet and of ejection of propellant.

The grammes of pellet is same, so change is from change in the grammes of the gas.

Ideal Gas Law (http://en.wikipedia.org/wiki/Combined_gas_law) shows to send pellet at a constant speed a constant pressure of gas is needed for same temperature this means a constant volume of gas at that pressure.

The grammes of gas is proportional to volume so any change in jump by change of propellant is proportional to it's density.

CO2 is 50% heavier than air and I see a change in jump when LP5 was changed from CO2 to air years ago though the pressure in a CO2 cylinder is slightly lower than the Steyr regulator the grammes of CO2 realised is bigger.

Nitrogen is 97% of density of air so that will not change anything.So why not use Helium which is only 15% of grammes of air, and give littler jump, fill cylinders at Party Baloon Stores.

Paj

cgroppi wrote:The real benefit of nitrogen is that its 100% dry. Water vapor in air causes its pressure to vary with temperature much more than dry air or nitrogen (because of the partial pressure of the water). In car tires this matters because car tires see wide temperature swings: they heat up a lot after you drive on them for a while. The resulting pressure change for plain, un-dried air can be significant (like 20% or more).

I'm a little confused as to the science here and would like to understand, if possible. :) Plus, I have shot shot air rifle in both cold and hot, so I am curious. How is it that the presence of water vapor in air would cause the pressure of a tire/tank to change more relative to temperature than a tire/tank filled with pure N? Water vapor is still a gas, just like nitrogen, oxygen, etc and behaves similarly in terms of pressure vs. temperature in these circumstances. In simple calculations of pressure, the identity of the gas does not matter, only the quantity. If we use a more complex equation to calculate changes in pressure due to temperature where molecular size and interactions are considered, remember that air normally contains only 1-3% water vapor, rarely up to 5%. If water vapor does influence pressure changes more than other gases, would this small amount really have a significant effect? Unless you're considering that the water condenses into liquid in cold temperatures? Still, wouldn't it be a very small amount condensing, having a small effect on the pressure of the tire? And I certainly wouldn't want condensing water in my airgun tank, yikes!

Off topic, but curious: I have heard about the advantage of using nitrogen in tires to prevent oxidation of the tire rubber from the inside. But what about the oxygen outside, and perhaps more importantly, the UV rays?

Air used in airguns has usually been dried with a desiccant in the hand pump, or by the air system at the scuba shop. Also, air cylinders on an airgun typically see a relatively constant temperature. This ends up negating the main advantage of using nitrogen over air.

Once a factory-trained airgun mechanic told me to never use a hand pump, only SCUBA air. The reason is the hand pumps do not remove enough water and dust to keep your airgun in prime condition and prevent corrosion. The SCUBA shops can. This was after my air rifle was not working properly and he found corrosion inside. I had been using a hand pump in a dry climate. I don't know if newer hand pumps are any better, but I thought I'd pass that along. Does anyone know more about this?

Sorry, forgot to login, I'm not a "guest!"

melina wrote:Sorry, forgot to login, I'm not a "guest!"

Here's a good explanation for car tire applications:

http://home.comcast.net/~prestondrake/N2_FAQ_Q01.htm

Folks: In your car tires, there is some water vapor in the air that has been pumped in, so that if the temperature drops, the water vapor condenses into liquid and therefore you have less gas in the tire: your tire pressure drops. But SCUBA air is BONE DRY. ZERO WATER CONTENT. So that is not a concern for AP. Nitrogen is chemically inert, so on paper it does less damage than air at high pressure, which could oxidize the aluminum. ON THE OTHER HAND, one of the good things about aluminum is that once an ultra thin layer of oxide forms on the surface, the metal underneath is protected from further oxidation (this is quite unlike iron).

Sooo... it looks like air (dry SCUBA air) is safer for humans (a leak won't kill you), not really worse for the cylinder, and cheap, usually! But if nitrogen is easier for someone, what the heck.

Ricardo wrote: one of the good things about aluminum is that once an ultra thin layer of oxide forms on the surface, the metal underneath is protected from further oxidation

Somewhat, in pure dry air.

Otherwise the protection is limited - and why aluminium is normally anodised to build up a thick and coherent layer of oxide instead of a thin, fragile and porous layer.