Hi Malathi,

I think an empty bed residence time is equal to the empty bed volume divided by the flow rate.

Empty Bed contact Time in minute = ((Bed volume ft3 ) * 7.48 gallon / ft3) / flow rate gpm

Have a look at

https://www.sciencedirect.com/topics/immunology-and-microbiology/empty-bed-residence-time

please. You can learn something about engineering fundamentals of bioengineering.

The two above answers are correct.

Regards

Vit

Thanks for all answered persons

Empty Bed Contact Time is equal to the volume of the empty bed divided by the flow rate. The residence time (lifetime) of a substance is determined with the knowledge of the amount (or concentration) of that substance and the combined rate of loss of the substance from the reservoir.