Pressure Question?

Question

A tank holds liquid waste comprised mostly of water. It is vented to atmosphere. The tank has a diameter of 50 feet and a total depth of 30 feet, It is only half full. At a point five feet above the bottom of the tank, the pressure is approximately

Answer 1

15ft - 5ft = 10ft of water x 0.433psi/ft.

= 4.33psig + 14.7psi = 19.03psia.

= 4.33 / 14.7 = 0.3atm gauge + 1atm = 1.3atm. absolute.

0.3atm x 760mmHg / atm = 228mmHg gauge

plus 760mmHg = 988mmHg Absolute.

And, 0.3atm x 101.3kPa/atm.

= 30.4kPa gauge = 130.7kPa absolute.

Answer 2

Tank is 30' deep, 1/2 full = 15'. 5' above bottom = 10' deep.

Pressure = (rho * g) * h

= (62.4lb/ft^3) * 10ft * ft^2/144in^2

= 4.33 psi (gauge pressure)