What causes a pressure vacuum breaker assembly to chatter during flow conditions?

Chattering in a pressure vacuum breaker assembly during flow conditions primarily occurs due to an undersized assembly. When the assembly is undersized for the specific flow rate, it cannot effectively handle the volume of water passing through. This can lead to rapid fluctuations in pressure as the water attempts to move through the smaller-than-appropriate openings. The result is a condition where the air inlet valve rapidly opens and closes, causing the characteristic chattering noise.

This phenomenon is particularly noticeable because the assembly relies on an adequate size to maintain a stable pressure differential. When the assembly is not adequately sized, it disrupts the normal operation of the air inlet, leading to inefficiency and increasing the likelihood of chattering. Understanding this relationship is crucial in ensuring backflow prevention devices function correctly and reliably under varying flow conditions.