Board of Certified Safety Professionals (BCSP) Practice Exam

What is the pressure at 10ft below the surface in a tank containing gasoline with a specific gravity of 0.74 and a depth of 30ft?

1. 2.56 psi

2. 3.21 psi

3. 4.15 psi

4. 1.87 psi

The correct answer is: 3.21 psi

To determine the pressure at a specific depth below the surface of a fluid, you can use the formula: Pressure (P) = ρgh where: - ρ (rho) is the density of the fluid, - g is the acceleration due to gravity (approximately 32.2 ft/s² in imperial units), - h is the height of the fluid column above the point where you are measuring the pressure. First, since we're dealing with gasoline, we start by calculating its density. The specific gravity of gasoline is 0.74, which means it is 0.74 times the density of water. The density of water is roughly 62.4 lb/ft³. Thus, the density of gasoline can be calculated as follows: ρ = Specific Gravity × Density of Water ρ = 0.74 × 62.4 lb/ft³ = 46.13 lb/ft³ Next, we calculate the pressure at 10 feet below the surface. Since the total depth of the gasoline in the tank is 30 feet, the pressure at 10 feet is calculated with: h = 10 ft g = 32.2 ft/s² ρ = 46.13 lb/ft