What is the approximate friction loss for 100 feet of 5" hose flowing at 500 gpm using the condensed Q method?

To determine the friction loss for 100 feet of 5-inch hose flowing at 500 gallons per minute (gpm), the condensed Q method is used, which is a standard calculation method in fire protection engineering.

The condensed Q method provides a quick reference for estimating friction loss in large-diameter hoses based on flow rate. For a 5-inch hose, the friction loss calculation incorporates factors such as the diameter of the hose and flow rate. Generally, the friction loss can be approximated using the formula:

Friction Loss (in PSI) = C × (Q^2)

In this case, the constant (C) used for a 5-inch diameter hose flowing at various gpm values is determined from reference tables or empirical data, and it typically indicates that for a flow of around 500 gpm, the friction loss is expected to fall within the range of 1.0 to 3.0 PSI per 100 feet for this hose size.

Applying the condensed Q method to this specific case, the commonly found figure for a 5-inch hose at 500 gpm yields approximately 1.7 PSI for friction loss over 100 feet. Therefore, when considering the options and the calculations used, the choice of 1