An important data to know is the time and volume that a tank or container can drain liquids from the drainage valve using only the power of gravity.

Size – gallons per minute – Liter per minute

1" – 6 gpm – 22.7 lpm

1 1 /2 " – 13 gpm – 49.21 lpm

2" – 23 gpm – 87 lpm

2 1 /2 "- 35 gpm – 132.5 lmp

3" – 50 gpm – 189 lpm

4" – 91 gpm – 344.5 lpm

5" – 142 gpm – 537.5 lpm