If a standpipe riser is 150 feet tall and full of water, what would be the pressure at the bottom of the riser due to the elevation of the water column?

To determine the pressure at the bottom of a standpipe riser that is 150 feet tall and filled with water, it is essential to understand the relationship between the height of the water column and the pressure it generates. The pressure produced by a column of water can be calculated using the formula:

Pressure (psi) = Height (ft) × 0.433.

This formula derives from the fact that each foot of water generates approximately 0.433 psi at the base due to the weight of the water above.

For a standpipe riser that is 150 feet tall, the calculation would be:

Pressure = 150 feet × 0.433 psi/ft = 64.95 psi.

Rounding this figure provides a pressure of approximately 65 psi. This aligns with the choice labeled as the correct answer.

Understanding this calculation is vital for fire sprinkler fitters, as it helps them assess the pressure conditions within a system to ensure that fire-fighting efforts are efficient and effective, given that the pressure can influence water flow and distribution.