How long will a bottle of Nitrogen continue to supply gas to a device using 30 standard cubic feet per minute? The bottle is about 5' tall with pressure at 2200 psi.

A 5-foot tall by 9-inch diameter tank ("K" type) holds 1.76 cft of air at 1 ATM. At 2200 psi, or 150 ATM, that equates to 263 cft. So at 30 cft/min it should last a bit over eight minutes.