Nitrogen for air rifle ?

[Grape712]

I no this has been covered before but I can't find it.What are the advantages/disadvantages of using nitrogen,does it have any effect on the gun itself?

[GOVTMODEL]

...won't hurt the gun, air is ~80% nitrogen anyway. Where you may run into problems is getting someone to fill an air tank with nitrogen, or getting air fittings on a nitrogen tank.

[Rover]

Why would you bother? It's not as cheap or readily available as air. The post above has it exactly right.

[Grape712]

nitrogen is drier and constant pressure at diferent temperatures

[Rover]

So what?

[GOVTMODEL]

nitrogen is drier and constant pressure at diferent temperatures

...is as dry as the vendor cares to make it.

I didn't know nitrogen had an exemption from the Ideal Gas Law:-)

[jhmartin]

nitrogen is drier and constant pressure at diferent temperatures

Air tanks filled at a reputable vendor (scuba shop) are just as dry.

There are two main reasons that car owners have their tires filled with nitrogen:
1) Less migration of the gas thru the rubber in the tire ... over a long term ... not really applicable as you are filling your >>metal<< cylinder on a weekly basis anyway (you are practicing right?) ... so this reason does not apply.

2) Yes, less pressure variability due to temperature swings, but this is true for a several hundred degree temp swing ... such as racing tires. At the ambient level of only about 30-40°F temps swings going from an indoor to outdoor range this is another non-applicable reason.

Also, I don't know about the manufacturers, but in the Anschutz manual it says "only air". Don't know if there would be warranty issues, but why risk it ... use air ... it's cheaper too

[John C]

I think the real reason to go with nitrogen is that you can easily rent a 6k psi tank and have it delivered to your house. If you don't live near a scuba shop (some won't fill tanks for folks without a scuba card) and/or practice a lot so that you're constantly refilling your 3k psi tanks, a large nitrogen tank is very handy. Commercial nitrogen tanks are much larger and filled to double the pressure, holding many times as much gas as scuba tanks.

This doesn't really apply to this forum, but big bore air rifle shooters, go through a lot of gas in a hurry. They either buy their own compressors or get nitrogen tanks.

I use scuba, since I can get fills easily, but I think there are valid reasons to use nitrogen.

-John

[jhmartin]

I think the real reason to go with nitrogen is that you can easily rent a 6k psi tank and have it delivered to your house. If you don't live near a scuba shop (some won't fill tanks for folks without a scuba card) and/or practice a lot so that you're constantly refilling your 3k psi tanks, a large nitrogen tank is very handy. Commercial nitrogen tanks are much larger and filled to double the pressure, holding many times as much gas as scuba tanks.

Doing this w/o a pressure reducer is a disaster waiting to happen ... one of the reasons air is much safer is there is NO possibility of an overfill.

[John C]

Doing this w/o a pressure reducer is a disaster waiting to happen ... one of the reasons air is much safer is there is NO possibility of an overfill.

Yes, it is. Fortunately, several small companies provide regulators specially for airgunners. http://www.airtanksforsale.com/ is one, but there are others. This company makes deadheads that will show the pressure remaining in your tank, as well.

You are right that scuba air (at 3k psi/200 bar) generally has no danger of overfill, but 4500 psi/300 bar SCBA tanks are becoming more popular. The same type of regulator is needed for safe fill.

-John

[robf]

Doing this w/o a pressure reducer is a disaster waiting to happen ... one of the reasons air is much safer is there is NO possibility of an overfill.

You don't need a regulator, just a careful approach. If you have something like a 50L or a valve that's a little hard to operate easily, get a flow restrictor put in. On my 3L 300 bar bottle I can throw the tap wide open and it will take about a minute to get from 100 to 200 bar.

No need to complicate or scaremonger, just careful responsible use. If you can't fill a bottle safely, it's questionable as to if you have the requirements to own even an air rifle...

[rmca]

I use scuba, since I can get fills easily, but I think there are valid reasons to use nitrogen.
-John

You won't get any more accuracy or precision from your air rifle if you use nitrogen.
As described above, the differences in pressure from temperature changes are tiny, and that's what the regulator in your rifle is there for (as the pressure from your cylinder goes down your pellets stay on track, right?)
As for dry air, it's only a problem when you fill the cylinder. Most compressors have some sort of moister filter in them.
The third reason being cost, I don't think that filling a tank with nitrogen will be cheaper than filling with just air, but I may be wrong.

What are your reasons for using nitrogen other than the ones described?

Cheers

[John C]

rmca;

I guess I wasn't clear. I don't think there's any substantial technical reason to use nitrogen over compressed air. I think the only reasons are availability, convenience, or price.

-John

[rmca]

John C

I must have miss understood... Then we agree on the technical side.