What is the correct procedure to begin testing a Reduced Pressure Zone (RPZ) device?

To begin testing a Reduced Pressure Zone (RPZ) device, the established procedure involves flushing all test cocks, starting with test cock #4. This approach is critical because it ensures that any remaining water or debris in the system is cleared out before beginning the actual testing. Flushing helps to maintain the integrity of the test and avoids any potential issues that could cause inaccurate readings during the backflow test.

By starting with test cock #4, which is connected to the relief valve, you ensure that the system is properly primed and that the testing sequence will give you the most accurate results possible. This method helps to eliminate any residual pressure or water from the test cocks that could affect the performance of the RPZ device and lead to improper functioning or wrong testing outcomes.

Choosing to start with a specific test cock, like test cock #1 or focusing only on the relief valve without flushing, does not adequately prepare the entire system for accurate testing and may overlook the importance of verifying the condition of all components involved in the backflow prevention device.