Backflow Prevention Practice Exam

Two valves of a five-valve differential pressure gauge are used to ____?

1. Bypass water for a leaky shut-off valve

2. Compensate for leaks

3. Purge trapped air from the gauge

4. Stop backflow during a field test

The correct answer is: Purge trapped air from the gauge

The purpose of the two valves on a five-valve differential pressure gauge is primarily to purge trapped air from the gauge. When using differential pressure gauges, it is crucial to ensure that the readings are accurate and not influenced by trapped air, which can cause erroneous pressure measurements. The valves facilitate the process of removing air from the system, allowing the gauge to give a true representation of the differential pressure across the points being measured. While other functions such as bypassing water for leaks, compensating for leaks, or stopping backflow during tests might be relevant in different contexts, they do not pertain directly to the specific function that the two valves serve in relation to ensuring accurate pressure readings. Purging trapped air is vital for the performance of differential pressure measurements, as air pockets can cause fluctuations and inaccuracies in the readings.