Rhode Island Journeyman Plumber Practice Exam

In plumbing terms, what does the term 'air gap' refer to?

1. A minimum distance between two pipes

2. A separation to prevent backflow

3. A device to measure pressure

4. A type of plumbing vent

The correct answer is: A separation to prevent backflow

The term 'air gap' refers to a separation that prevents backflow, particularly in plumbing systems. This is an important safety feature designed to protect the potable water supply from contamination. An air gap is typically created by ensuring that there is a physical vertical space between the outlet of a plumbing fixture, like a faucet, and the highest point of the water in a fixture or a drain. By maintaining this gap, it ensures that if there were a drop in water pressure or a backflow condition, contaminated water cannot siphon back into clean water supplies. In plumbing applications, this concept is crucial in scenarios such as sinks, dishwashers, and other water fixtures, where it's essential to prevent waste water from re-entering the clean water supply. Understanding the air gap's role in backflow prevention is fundamental for maintaining health and safety standards in plumbing installations.