Ask your friend about the service pressure on that bottle. Most smaller N2 bottles I've seen are 2200psi. If you're friend owned the bottle, you shouldn't need a contract to get it filled...the contract is usually a lease agreement for the bottle. Here you just pay for the contents if you own your own bottle.

The bottle will also have a hydrotest date on it...if it's expired, it'll need to be re done. This is your bill if the bottle is owned.

Bottled nitrogen is dry...no water. Air is mostly nitrogen along with varying percentages of other gases (and usually some moisture). There will be a very slight performance increase with nitrogen...VERY slight.

Cost of fittings/fill apparatus will vary greatly depending upon what you have...and what you want. Let's find out if the bottle is useful first eh?

Al