Sizing of a catch basin for roof drains and/or water bottoms

[HFCkh]

Is there a method to calcuate the size of a catch basin or sump for collecting roof drains or water bottoms off a storage tank? Been searching through API650 and I cannot find a general equation which relates the tank size to the size of the catch basin. Any help would be appreciated

 

[khardy]

I’ve never heard of a code required size or a special formula. 650 certainly doesn’t have one. I think you just use common sense considering: 1) the expected flow rate, 2) the frequency of use, and 3) the amount of water expected (in the case of a water bottom collection.)

The expected flow rate is a function of the max height, the diameter of the sump / drain piping, and in the case of floating roof drains, the max rainfall rate.