Ok
You are inhaling nitrous right now,the pooling theory is bull..dentists give it to you,yes its cut with oxygen,but so are whippits(catering gas)
If you live in the proper place you can get 60lb tanks filled for about 100$..unless the tank valved needs to be converted from co2..that'll cost another 50$..unless you have your own tank(I have 3) you will have to rent the steel..another 200$,but you'll get that back when you return the tank..you won't get mefical gas unless you're cool with the guy at the filling station..they'll try to give you gas with sulfer dioxin in it so you won't huff it..there are two ways around this..one,talk to the guy and explain your chevy vega with bored out small block 454 took 2 years and 40k to buils and you don't want sulfer running through your engine,it'll pit the metal in the bores and cylinders..and you don't want other racers smelling your car running nitrous(when sulfer burns in an engine it stinks) the other way is to go to an armysurplss store,get a wwII gasmask cartrdge(its a carbon filter) and fashion a reducer around the filter till its down to an inch,get an ACRYLIC hose(it will freeze but not break) and hose clamp it to the nozzle..presto..clean gas that is almost medical grade..any questions p.m. me,I blew gas on tour for years.ill probably have an answer for ya..happy huffin!