Water Reservoir and Siphon Pipe

Engineer Steve has been sent to inspect a water reservoir with a pipe acting as a water siphon. He would like to find out if the pipe is installed properly so that cavitation will not occur inside the pipe. If cavitation does occur, what should he recommend to change the system? The dimensions of the system are given in the figure.

Determine the pressure at point 2 for the current system. Find the allowable height of the pipe such that cavitation will not occur.

• Assume that points 1, 2 and 3 lie on a streamline, and Bernoulli's equation is applicable.
• For constant diameter pipe, the velocity at points 2 and 3 is the same.
• Cavitation occurs at a vapor pressure of p_v = 2.34 kPa (abs).
• Assume the tank is large so that V₁ = 0.
• Assume the outlet of the pipe is acting like a free jet, i.e., p₃ = 0.
• Assume the density of water is 1000 kg/m³.