Nitro Piston Air Gun: Benefits & Mechanism Explained

[rws45user]

Hi. After watching this short youtube video of a nitro piston air gun . Can someone tell me how compressing a piston filled or partly filled with nitrogen ,how this can force the piston forward to force the pellet out of the barrel once the piston is released from its compresses state .Is there some type of heat being generated when the piston expands to the uncompressed state. http://youtu.be/b741fQL8BRU Thanks in advance.

 

[SteamKing]

After being compressed, the nitrogen will naturally re-expand in the cylinder when the trigger is pressed. If you blow up a balloon and release it, what happens?

 

[rws45user]

Then why not just use air ,what does having nitrogen compressed and released have a advantage over just air . Is heat generated when the nitrogen is uncompressed .

 

[Borek]

I suppose you could use air without changing the performance much. But you probably want the gas in the chamber (cylinder? not sure how to call it) to be dry and non-corrosive, and nitrogen is an obvious candidate then.

 

[rws45user]

What is going on with the nitrogen molecules that causes it to expand at a higher rate of speed than air ,and forces a piston forward with more force when nitrogen is being used than using just compressed air . How is the same nitrogen being used over and over again to produce the same effect being compressed then allowed to expand in a sealed chamber. The air in front of the nitrogen chamber in the same chamber that has just air in it forces the pellet out of the barrel . nitrogen in the chamber is somehow pushing the air filled part of the chamber faster than just compressed air behind the piston. Its the same chamber but nitrogen is behind the air with seals keeping them separated .

 

[rws45user]

here is a picture of what is going on with the nitrogen look at the picture at the bottom of the page . thanks for your help with this. http://www.bsaguns.co.uk/grt_lightning_xl-se.php

 

[Borek]

If I understand the construction correctly, the nitrogen chamber is sealed and it uses the same nitrogen gas all the time. What is inside doesn't matter much - any gas would behave similarly. If you have ever played with a syringe you are probably aware of the fact compressed gas behaves like a spring - the more compressed it is, the stronger it pushes the piston. So basically you have a sealed syringe in the place where standard design air gun uses a spring, and you compress and decompress the nitrogen inside when using the gun. Nothing more complicated.

And as I signaled earlier I doubt nitrogen was selected because of its "ballistic" properties - any dry gas would be about as effective. Sure, there are differences - but most likely nitrogen just happens to have a very good ratio of price to performance (and being dirt cheap can be difficult to beat).

 

[rws45user]

Yes you your right its being used again and again. There are air guns that compress air in a chamber and even at 3,000 psi are not sending a pellet out as fast as the guns that are using compressed nitrogen . How is nitrogen pushing the piston forward faster than air that is being compressed at very high psi's

 

[Borek]

No idea.

Is the difference large? Some differences can be attributed to average molar mass, humidity of the gas, compressibility factor - but I would not expect them to be higher than just a few percent.

 

[rws45user]

yes its a big difference .chambers that are being filled with compressed air are getting close to 4,000 psi . the end result is the fastest compressed air gun with 22 caliber is around 900 fps and the nitrogen chambers are pushing the 22 cal pellets out at 1200 fps in the new bsa gun in airgun's that a big difference .Its important because its the ft lb energy that the pellet hits the animal .at 1200 fps the it produces about 50 lb ft . while a 900 fps gun is only 20 lb ft energy. I think the air chambers are at there max now and are being filled to dangerous levels of pressure and have to be filled with air compressed in scuba tanks to refill the guns and pumping air in the chamber using a foot pump is getting to be impossible to pump by hand. But using a gun that uses the nitrogen filled chamber is a easy gun to cock and compress the nitrogen chamber with only one cock. and it produces much faster fps's in pellet speed . Its not as smooth as the compressed air . they call this gun a pcp . The nitrogen filled guns are faster but not as smooth as the pcp guns because of the piston moving forward . but the pcp's have to be refilled by a tank. So for hunting you want more power and for target's you want less recoil. There is a new gun made by FS that has a built in pump that compresses air as you pump up the gun ,its a pcp gun but no need for a tank .but still slower than the nitro piston .