LPM also known as a litre per minute (also liter per minute in American English, lpm, and L/min) is a derived SI unit of measurement of volumetric flow rate that is equivalent to one litre of volume flowing every minute.
1 lpm = 0.0353 cubic feet per minute
In the HHO field the LPM is the measurement unit for the quantity of HHO (hydroxy or oxyhydrogen) gas produced.
As a consequence of LPM measurements, the hho generators (electrolysers) tend to be classified using the LPM values.