Question

5. A water tower is approximately 150ft above grade. A 6” mainline bursts flooding the street. The supply pump to the tower can maintain up to 800gpm flow rate. Is the water level in the tower being maintained, or is it falling, why? Assuming the system could maintain the current water level how many gallons would be lost in 15minuets time

Answer 1

GIVEN:

Height of the tank, H = 150ft.

the diameter of the mainline, d = 6^" = 6 inches = 6/12 feet

Rate of water flowing in the tank,

SOLUTION:

We know that the volume flow rate, Q

Q = Av

here, A - area of the cross-section through which the water is flowing

v - velocity with which the water is flowing

Therefore, the water coming out of the mainline is given by

  

here,

Therefore,  

  

  , Therefore, water is flowing out.

Now,

since

The total water flowing in the tank in 15 minutes, i.e., in 900 seconds is

  

Similarly, the water flow out of the tank in 15 mins is,

Therefore, the net amount of water flowing out of the tank is

  

   the required net amount of water flowing out of the tank in 15 mins.