Question

Assuming that the pump is located at the bottom of the well, how much pressure would it need to generate to pump the water up 263 feet and still have 40 psig available for the well users. The local air pressure is 760 mm Hg

options:

a) 168.7 psi

b) 114.0 psi

c) 50.0 psi

d) 154.0 psi

Answer 1

Absolute pressure at the bottom P1 = gauge pressure + atmospheric pressure

= 40 psig x 101325 Pa/14.7psi) + 760 mmHg x 101325 Pa/760mmHg

= 275714.29 + 101325

= 377039.29 Pa

Velocity of at the reservoir V1 = 0

Pressure required P2 =?

Distance traveled by water = 263 ft x 1m/3.28084ft

= 80.1624 m

Apply the Bernoulli's theorem

P1 / (density x g) + z1 = P2/(density x g) + z2

P2 = P1 + (z1 - z2) x g x density

P2 = 377039.29 + (80.1624 x 1000 x 9.81)

= 1163432.43 Pa

P2 = 1163432.43 Pa x 14.7psi / 101325Pa

= 168.7 psi

Option A is the correct answer