I purchase “Beer Gas” (guinness mix - 75/25 Co2/N2) which would be used for a nitrogenated product with a stout faucet like stouts and some ales. Then there is also a 60/40 mix which would be used for a remote draw system where your lines were very long and the additional pressure was needed - this gas might be used for a restaurant where kegs were in a walk in cooler in the basement and they had insulated glycol trunk lines going from walk-in to taps in the bar area.
Supplier near me is Maine Oxy which is primarily a welding gas supplier but also deals in beverage grade Co2 and N2 gasses. Welding suppliers are usually a good source. note that the beer gas can come in different % mixtures for different end uses.
I personally don’t see a value in Buying gas tanks as you also take in the task of recertification every 5 years. So i go with exchange instead. Maine Oxy will exchange even out-of-certification tanks for new/certified if they gave me the original ones and so not having to deal with that is a big hassle-eliminator for me. My beer gas tanks are always steel but my CO2 are aluminum 5# tanks. My regulators are all tap right or micromatic brand and the gas supplier also sells regulators and gas related parts if needed.
