What is the pump discharge pressure for supplying a prepiped elevated master stream through 200 ft of 4-inch hose?

When supplying a pre-piped elevated master stream through 200 feet of 4-inch hose, the pump discharge pressure must account for the friction loss in the hose. For 4-inch hose, the friction loss is typically estimated to be around 10 psi per 100 feet of hose. Therefore, for 200 feet of 4-inch hose, the friction loss would be approximately 20 psi, as it doubles the length.

In addition to the friction loss, there is the requirement to maintain enough pressure at the base of the elevated master stream. The general rule of thumb for operating an elevated master stream is to ensure a minimum of 100 psi is supplied at the base.

Combining these two components:

1. Friction loss for 200 feet of 4-inch hose is roughly 20 psi.

2. The minimum discharge pressure to effectively operate the elevated master stream is typically around 100 psi.

Thus, the total pump discharge pressure calculation becomes:

100 psi (minimum for the master stream) + 20 psi (friction loss) = 120 psi.

However, keeping in mind that elevated master streams often require additional pressure for effective operation and overcoming any additional losses in the system, a more commonly accepted figure for operational discharge pressure is