An MWS apparatus is resupplying 1,000 gpm to a pumper 4 feet below. What is the required pump discharge pressure (PDP) given 50' of 5-inch hose?

To determine the required pump discharge pressure (PDP) when resupplying water to a pumper 4 feet below using 50 feet of 5-inch hose, it is essential to calculate the total pressure loss due to elevation and friction.

First, for the vertical lift, the pressure decrease caused by the elevation difference needs to be considered. Since the pumper is located 4 feet below, this contributes a negative pressure of 4 psi (using the conversion that 1 foot of water equals approximately 0.433 psi; therefore, 4 feet is equivalent to 4 psi).

Next, we need to calculate the friction loss in the 50 feet of 5-inch hose. For 5-inch hose, the friction loss is generally found from tables or empirical formulas. On average, the friction loss for a 1,000 gpm flow rate through 5-inch hose is about 1 psi per 100 feet. Thus, for 50 feet, the friction loss is approximately 0.5 psi.

Now we add the elevation loss and friction loss together to find the total PDP. The needed PDP must not only counteract the elevation drop but also ensure sufficient pressure to maintain flow through the hose. So, we calculate