Cross Connection Practice Exam

A perfect vacuum (at sea level) will raise water in a pipe a maximum of what height?

1. 30.5'

2. 33.9'

3. 36.5'

4. 40.0'

The correct answer is: 33.9'

The maximum height that a perfect vacuum can raise water in a pipe at sea level is approximately 33.9 feet, which is derived from the principle that atmospheric pressure can support a column of water. At sea level, standard atmospheric pressure is about 14.7 pounds per square inch (psi), which can support a column of water based on the density of water. The calculation involves the height of a water column supported by atmospheric pressure, where the height (in feet) can be determined using the formula: Height = (Atmospheric pressure in psi) x (2.31 feet/psi). Using this formula, you find that: Height = 14.7 psi x 2.31 feet/psi ≈ 33.9 feet. This demonstrates how atmospheric pressure acts to support the weight of a water column when a vacuum is created above it. The understanding of this principle is fundamental in various fields, including hydraulics and plumbing, where cross-connection control is crucial to prevent backflow and potential contamination of water supplies.