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**DyePbGuy** · February 27th, 08:35 AM

Does Nitrogen compress in the cold and expand in the heat?

I either have a leak on my new MacDev tank or it compressed because I left it out in the cold last night 40 degrees or so.

Any imput?

***onesikpup*** · February 27th, 08:55 AM

im sure it would changer a littlle, but i doubt it would be much. warm it up and find out.

**MovingTarget** · February 27th, 01:52 PM

Of course it does. It can't violate the laws of physics. But it does it much less and much less violently then CO2, making it MUCH better for colder temps.

**DyePbGuy** · February 27th, 07:28 PM

I guess I really didn't state the question the way I should have.

I filled my tank up to 4400psi, after the gauge settled it was about 4000psi. I left it in my car over night in around 40 degree weather and when I got it out in the morning, it was around 3000psi. I then proceeded to shoot three full hoppers of balls to see what would happen and the gauge stayed at 3000psi.

conclusion is, my theory was correct. I just didn't think the cold would effect it that dramatically

**burningcow422** · February 27th, 09:45 PM

question..could it just be the regulator?

for stupid people like me, im thinking that the regulator can read differently than the actually pressure in the tank.
i was gonna start a thread about this.

**bobide** · February 27th, 09:52 PM

no, ur thinking of the gauges. The reg just regulates. Unless ur speculating that the reg is not putting out the pressure it says it is. Which is the gauge and the reg.

**burningcow422** · February 27th, 09:56 PM

yeah i did mean the guage. stupid me.

Torch · February 27th, 09:59 PM

It could be a bad gauge I guess.

When a HPA tank is filled the air inside it is warm, so as it cools it is natural for the pressure to drop. If the tank is cooled, the pressure will drop more. When you took it out of the car and were using it, I'm going to assume it was absorbing heat from the air and maybe sunlight. That would have brought the pressure back up.

In short, you were right. Nitrogen/HPA changes pressure under different temperatures. It isn't nearly as sensitive as CO2 is however, and your output pressure is controlled by the reg, so it will be consistant where CO2 would not.

***xPiZZeRx*** · February 27th, 11:53 PM

I don't know man.

I'm pretty sure that nitrogen isn't effected by temperature at all, deffinitly not that much.

I'm pretty damn sure that sunlight couldn't effect it that much, especially in the winter. I'm also pretty sure that the temperature inside your car, and the temperature outside would effect it that much, they probably are nearly equal.

Bad gauge? Possible. You sure you're reading the gauge right, lol?

Torch · February 28th, 12:09 AM

It sounded like a good enough explination to me. the volume of the tank can't change, so if the temperature changes then the pressure has to. I didn't think it would be that great a change either but I didn't know for sure.

Alpha · February 28th, 05:46 AM

Quote:

Originally Posted by Torch

It could be a bad gauge I guess.

When a HPA tank is filled the air inside it is warm, so as it cools it is natural for the pressure to drop. If the tank is cooled, the pressure will drop more. When you took it out of the car and were using it, I'm going to assume it was absorbing heat from the air and maybe sunlight. That would have brought the pressure back up.

In short, you were right. Nitrogen/HPA changes pressure under different temperatures. It isn't nearly as sensitive as CO2 is however, and your output pressure is controlled by the reg, so it will be consistant where CO2 would not.

Exactly. When you get it filled, teh tank is warm, corrrect? This is becuase the molecules are beign squeezed into the tank, causing some massive leg-rub. Okay so its just friction, but it warms up teh air in the tank. And later on when the gas cools, the pressure can change a little bit.

But in terms of spikes and shootdown, nitro tanks are way above CO2 still.

**HP_lovecraft** · March 2nd, 12:18 PM

Quote:

Originally Posted by xPiZZeRx

I'm pretty sure that nitrogen isn't effected by temperature at all, deffinitly not that much.

Nitrogen, like all gases, is EXTREMELY effected by temperature.
Thats why, as noted above, you can loose 30% just from a hot fill. (and, as side effect, gain 30% from the reverse).

By all accounts, nitrogen is just as sensitive as CO2, but the difference is that nitrogen is stored 3,000 - 5,000 PSI. CO2 is stored around 500-1000psi.

Nearly all guns need at least 500psi to function, so if the cold makes the pressure drop below 500psi, then there is problems.

The real issue with CO2 is the refrigerant properties, leading to crogenic shootdown when rapid firing.

If CO2 was stored at 5,000 like Nitrogen, then nobody would probobly notice a difference. In fact, this is why some people used CO2/HPA mixes in the 90s.
The pressure of the HPA boosed the CO2 to "supercritical", allowing for the far better effeciency of the CO2, buffered with the HPa.

NIck

**tippmannbeast** · March 2nd, 06:05 PM

I'll bet that your gauge springs just got cold and contracted, then when you shot your marker they warmed up.

Co2 is t3h sux0rz IMO... I got cold burns from using it in my imp. My fingers went numb and now they're all dry and raw.

**DyePbGuy** · March 3rd, 07:43 PM

This is the most reply's I've ever gotten on a post. To tell you the truth I wasn't expecting this many. I knew already Nitrogen Compressed and expands with temperature. I just didn't know how dramatically it would be effected. Thanks for all the input, didn't learn anything new but maybe some one else did.

**lookatme123** · March 4th, 02:22 PM

well, i was out at a feild had about a half a tank, left the tank in the bed of the truck like an idiot, had pretty much no air after i took the tank in later that night.
I later shot some paint with the tank and it stayed about where it was just as you described.

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