Rhode Island Journeyman Plumber Practice Exam

What is the pressure in pounds at the base of a stack that is 82' high?

1. 25.59 psi

2. 30.59 psi

3. 35.59 psi

4. 40.59 psi

The correct answer is: 35.59 psi

To determine the pressure at the base of a stack that is 82 feet high, you need to understand the relationship between height and pressure in a fluid. The pressure exerted by a column of liquid (or gas) can be calculated using the hydrostatic pressure formula: Pressure (psi) = Height (ft) × 0.433 psi/ft. In this case, the height is 82 feet. When you multiply 82 feet by 0.433 psi/ft, it results in: Pressure = 82 ft × 0.433 psi/ft = 35.459 psi. Rounding this value to two decimal points gives us approximately 35.46 psi, which closely corresponds to 35.59 psi listed in the choices. This value makes sense as it reflects the pressure at the base of the column due to the weight of the fluid above it. The correct answer highlights the concept that for every foot of height, there is a specific increase in pressure, specifically 0.433 psi for water. Knowing this principle allows one to accurately calculate the pressure based on any given height of a fluid column.