Is it OK to use Nitrogen in a CA pistol?

[jlochey]

Folks,

I was wondering, does anyone actively use Nitrogen in CA pistol's like the LP10 etc?

The gun store near where I work, has ONLY Nitrogen, but will fill my cyclinders for nearly free...

Any reason to not use Nitrogen? I searched the board here and got some good information about this topic, but I was just wondering if anyone was doing this on a regular basis.


Thanks,



John

[Asa Yam]

If you fill your CA tank with compressed air, it's 78% nitrogen already. The only things you have to worry about are:

• Moisture in the nitrogen. A sudden pressure drop will cause this moisture to condense or freeze. This is why most compressed gas lines have liquid traps in them.
• Drying out the seals. I think most seals these days are synthetic, so this should not be an issue.

The speed of sound in nitrogen is just under 2% slower than that in air, meaning you'll get 7-9 FPS less at typical air pistol velocities.

Now, assuming your tank's pressure seals could contain HELIUM, you'd get an increase in MV, since the speed of sound is higher (about 2.8x higher). Hypervelocity guns (AKA - "light gas guns") use hydrogen or helium to achieve higher velocities. Such devices are akin to a spring piston air gun, using a methane-oxygen explosion instead of a mainspring.

Sources:
http://hypertextbook.com/physics/waves/sound/
http://en.wikipedia.org/wiki/Light_gas_gun

[Mark Briggs]

Please take a moment and do a search through past posts (the search function works very well for this). There was a thread on this topic sometime in the last couple of years, started by one of the shooters from India. He had asked the same question because nitrogen was readily available to him whereas SCUBA air was not. He transitioned to shooting nitrogen (can't remember which pistol, either LP10 or CM162) and reported no problems.

[jlochey]

Thanks Mark, yeah, I did read that exact thread earlier today.

I guess I was mainly wondering, if since that thread or in general, nitrogen usage was on the upswing or considered an OK choice.

I guess I was just looking for input from someone who was actively doing it right now...

Maybe I'll contact that gentleman from India directly with some questions...


Thanks again,


John

[Steve Swartz]

Stay away from the liquid nitrogen though- have heard it plays heck with seals!

(bu-duhmp-bump)

Steve Swartz

[Nano]

jlochey:

In my club, we charge the cilinders only with nitrogen, for the last 2 years we are shooting only with nitrogen, because for the altitude in my country, is not possible to put 200 bar in the the tanks, only is possible with nitrogen.

Nitrogen is cleaner than air, is better.

Nano

[Guest]

jlochey:
...we are shooting only with nitrogen, because for the altitude in my country, is not possible to put 200 bar in the the tanks, only is possible with nitrogen.

I have some trouble understanding why air in Bolivia, even up on the high planes (altiplano) at say 3600 to 4100 meters, cannot be compressed to 200 or even 300 bars.
The limiting factor must be the compressor, I recon...

[dflast]

I have some trouble understanding why air in Bolivia, even up on the high planes (altiplano) at say 3600 to 4100 meters, cannot be compressed to 200 or even 300 bars.
The limiting factor must be the compressor, I recon...

Yes indeed, the limiting factor is the compressor. While it's true that air molecules in La Paz are the same as air molecules in Seattle, because of the altitude a lot fewer of them get into the pump body on the intake stroke. At 10000 feet atmospheric pressure is only about .7 bar, so the pump compression ratio (240:1? I haven't tried maxing my Hill out) that comfortably exceeds 200 bar at sea level can only get to around 170 there.

As a corollary, I'd imagine it takes more strokes to fill a given cylinder in Colorado Springs than it does here on the shores of Puget Sound. Has anyone documented this?

-David

[Nano]

David:

La Paz is at 3600 meters above the sea level.
In the altitude, all the motors lost 30% of her power (10% for each 1000 meters) , if your car have 100hp in the sea level, here you have 70 hp.
he is comprehensible that the motors to explosion are affected by the height, so that the air contains less oxygen, therefore the internal explosion is poor.
The without explanation thing is that the height, also affects the electrical motors, but for example affects less to the motors with turbo charger.
Compressing that charge the air is more affected, we even make load the big tanks in the level of the sea and soon we transported them to the height.

Nano