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As far as metric units having real world meanings, it’s mostly about the math. It’s often considerably easier.
The customer buys extracts by the gram. What sense does it make to track your inventory in anything other than kg?
Potency is returned in mg/g, sure you can use percent. What the fuck is 72% of a lb? 72% of a kg?
And butane goes below one bar(absolute) at ~0C.
Boiling point is the temp where vapor presser exceeds ambient (usually 1atm/1bar)…if you reduce pressure (pull vac), boiling point goes down.
Point is you can trivially put the genie back in the bottle (butane in your tank as a liquid) at 30C with that pump.