Calculating Water Tower's Drain Pipe Flow Rate

[yuvlevental]

A water tower, vented to the atmosphere, is drained by a pipe that extends to the ground. The top surface of the water in the tank is 13.3 m above the ground. If the valve in the drain pipe is closed, what is the absolute pressure in the drain pipe at ground level?
2.32×105 Pa

If the valve is now open and the cross-sectional area of the drain pipe is 1.69E-2 m2, find the volume flow rate in the drain pipe. Assume that the water speed at the top of the water in the tank is negligible.

Are the pressures at top and bottom the same when the drain is open?

.5*1000*(v1^2)=1000*-9.8*13.3

v1*1.69E-2=volume flow rate

Am I right?

 

[Pyrrhus]

Hello, is the drain pipe directed vertical from the center of the tank to ground level?

 

[yuvlevental]

the drain pipe starts at ground level and goes under

 

[Pyrrhus]

the drain pipe starts at ground level and goes under

so ground level is the bottom of the tank?

What's the tank's height?

 

[yuvlevental]

13.3m, yes, ground level is the bottom of the tank

 

[Pyrrhus]

Well if the tank is open both at the top and the bottom, what do you think the pressure will be? both are open to the atmosphere in said points.

 

[yuvlevental]

both pressures would be the same, because both points are exposed to the atmosphere. So is the rest correct?

 

[Pyrrhus]

both pressures would be the same, because both points are exposed to the atmosphere. So is the rest correct?

Yes, the same.

The rest is right.

You need to apply Bernoulli equation at the top of the tank and at the drain pipe.