If the water level in a reservoir is 150 feet above a fire hydrant, what is the static pressure reading at the hydrant?

To determine the static pressure reading at the fire hydrant when the water level in a reservoir is 150 feet above, you can use the basic principle of hydrostatics, which states that the pressure exerted by a column of water is directly proportional to its height. The formula for calculating the static pressure in pounds per square inch (psi) based on the elevation of water is:

Pressure (psi) = Height (feet) / 2.31

Using this formula, if you substitute 150 feet for the height, the calculation would be:

Pressure = 150 feet / 2.31 ≈ 64.93 psi.

When rounded, this value aligns closely with the answer choice of 65.1 psi, which matches the calculated static pressure at the fire hydrant. This reflects the understanding that the height of the water column directly influences the pressure available at the discharge point, in this case, the fire hydrant. Therefore, based on the principles of fluid dynamics and the relationship between height and pressure, the answer is justified.