This depends on your Litres Per Minute (LPM) Setting:
 
  1 LPM 2 LPM 3LPM 4LPM
C 410 265  137  103 
D 1500  750  500  375 
E 4000  2000  1333  1000 
G 8900  4450  2967  2225 

All Figures are in minutes and relate to Oxygen only