# flow rate surface tension

fdnovice7629
Member

hello

i have a drip tube with water dripping and when i increase the flow rate or frequency of drips they get bigger/more massive.

i see the equation mass x gravity = 3.14(tube diameter)(surface tension)

my mass is changing but not gravity, 3.14 or tube diameter so surface tension must be related to flow rate but I cant find anything online on how to figure this out.

conversely I have a known flow rate and mass and want to determine tube diameter but unsure how to get it as it appears surface tension must be related to flow rate but I dont know how

## Answers

Surface tension is a material property so is generally constant for a given temperature.

The above equation is some sort of force balance which would (usually) be solved to find the mass given the other values are generally known.

I assume the 3.14 is PI to give the tube circumference?

I don't think you can use that equation for mass flow as the units don't balance.

i have a known flow rate and known mass of the drip and need to determine the diameter of the tube

A quick google found a Researchgate paper, droplet rate from tube