we used medical grade nitrous when possible
but we could not always get it!
.
If you are at a shop that is not used to filling bottles...beware to some degree. They should have a quality scale and put in a set amount of NO2...so many pounds. A local engine shop started filling bottles and I had one that was over filled...later in the day the blow off valve blew due to expansion. It was a waste of the gas + cost of replacing the valve. This shop was using a bathroom scale (and many do without incident).
medical supply company. silly.
LOL, yea right. Nitrous used for racing has sulphur so it cannot be huffed. Medical grade Nitrous cannot be purchased unless you have a licsense.