Dry Air ?

"JC1234"I use 6000psi nitrogen I get from airgas $90 a year for the tank plus 140 for the gas and that will last me about 4-5 months before I have to refill, I shoot a lot.

Are they filling your bottles or swapping them out ? When I checked with Airgas they swapped the bottles and wanted me to pay for a full bottle even though I would return around 1/3 of the contents.
 
Thurmond, and others, I'm brand new to PCP, haven't even ordered a Marauder yet. Where would I find nitrogen, tank rental, etc? Machine shop? Fire station? Will nitrogen work or harm something like a carbon fiber Great White tank and a Marauder rifle? 


Ouch, I am paying $50 a year for the tank and $70 for the gas on my 6K N2 and it appears that I am also getting about 5 months.Thurmond
 
AllilnLL,

Before you delve into the big and heavy 6000 psi nitrogen bottles, I'd suggest looking around your area for dive shops. Some, like the one local to me, will fill your tank for free if you bought it from them. I get free visuals as well. But, this particular shop can only fill to 3000 psi, so I am limited to a SCUBA tank. However, a lower pressure tune on a Marauder allows for sufficient number of rifle fills before I need to take a trip into town. There are no local places that can fill to 4500 psi that the carbon fiber SCBA bottles can handle.

In my area, the lease of a 6000 psi nitrogen bottle costs a bit more than $100 per year, and fills are not as inexpensive as others have expressed. Also, the local welding supply places will NOT deliver to a residence; it must be at a business. The extra expense has a lot to do with how far from the fill point the bottles have to travel. In my case it is ~250 miles one way. 

The other significant expense with the high pressure nitrogen is you really need a regulator that can handle the high input pressures and have a rather high output pressure as well. A regulator that takes the 6,000 psi down to 60 psi is rather inexpensive compared to one that takes the 6,000 psi down to 4,500 psi. The reason for the higher cost is due to mass production. Every welding shop and industrial environment that needs a lot of nitrogen, usually, has little requirement for high pressure, but needs lower pressure. Or, they are making small amounts of liquid nitrogen for which a regulator really is not needed. Filling a bottle to 4,500 psi is rather a niche application.

 
"AlliInLL"Thurmond, and others, I'm brand new to PCP, haven't even ordered a Marauder yet. Where would I find nitrogen, tank rental, etc? Machine shop? Fire station? Will nitrogen work or harm something like a carbon fiber Great White tank and a Marauder rifle? 


Ouch, I am paying $50 a year for the tank and $70 for the gas on my 6K N2 and it appears that I am also getting about 5 months.Thurmond
Carbon Fiber Tanks should more properly be called
Carbon Fiber "Wrapped" Aluminum Tanks (no gas touches the Carbon Fiber). 

Atmosphere From Wikipedia:

By volume, dry air contains 78.09% nitrogen, 20.95% oxygen, 0.93% argon, 0.039% carbon dioxide, and small amounts of other gases. Air also contains a variable amount of water vapor, on average around 1% at sea level, and 0.4% over the entire atmosphere.

As you can see Nitrogen is mostly what everyone shoots anyway. It is an inert DRY gas that is approved for ALL PCP guns.

Oxygen, CO2 and water combine to cause problem in a PCP that is why a DRY gas is needed.
Oxygen and water = Rust and corrosion.
CO2 and Water = Acid = Metal corrosion.
Neither of these is good when dealing with pressure vessels.

N2 is from welding supply shops and since they are 80 miles from me I always pick up and transport my own bottle but know that a 6K N2 bottle is about 300lbs. Dive shops supply breathing air as detailed in the Wikipedia description above as do fire stations that are willing to fill bottles. As Joe Brancato states on his site do not buy a tank UNTIL you are sure of a source to fill it.

Thurmond