Where should the connection pipe from the air supply to the DPV enter the system?

The correct choice indicates that the connection pipe from the air supply to the Double Check Valve Assembly (DPV) should enter the system above the priming water level. This is essential for maintaining proper operation of the valve assembly.

When the connection is made above the priming water level, it ensures that air can be introduced into the system without the risk of contaminating the water supply. This positioning allows the system to maintain the necessary water seal within the valve assembly, preventing backflow and preserving the integrity of the water supply.

Entering the system above the priming water level avoids potential situations where water could flow back into the air supply line, which could lead to significant system malfunctions and potential health risks due to contamination. Proper positioning is crucial in fire protection systems, and adhering to the code requirements regarding the placement of connection pipes helps ensure safety and compliance with industry standards.