When utilizing three unequal lengths of hose to supply a monitor, how do you determine the gallons per minute (gpm)?

To determine the gallons per minute (gpm) when utilizing three unequal lengths of hose to supply a monitor, it is essential to assess the overall pressure and associated friction loss in each line. Friction loss occurs as water flows through hoses, and it can vary significantly based on hose length and diameter, as well as flow rate.

Choosing to find the total pressure in each line due to friction loss and using the higher of the two is correct because the gpm capacity of the monitor will be limited by the line with the highest friction loss. This ensures that you account for the worst-case scenario regarding pressure drop, allowing you to understand the maximum flow rate achievable through the three hoses. By identifying the line with the higher pressure drop, you can more accurately predict the effective gpm when the monitor is in operation.

Other methods, such as using the lower pressure from the hoses or averaging the pressures, do not provide a reliable determination of gpm since they could underestimate the flow capacity or fail to account for the most significant pressure loss affecting overall performance. Therefore, relying on the highest friction loss offers the most prudent approach to ascertain flow limits when connecting hoses of unequal lengths.