The application of a pressure vacuum breaker is for:

A pressure vacuum breaker (PVB) is specifically designed to prevent backsiphonage, which occurs when there is a negative pressure in the supply line, allowing contaminants to be drawn into the potable water system. The design of the PVB incorporates an air inlet that opens when there is negative pressure, breaking the vacuum and allowing air to enter the system, thereby preventing backsiphonage.

In addition to its primary function of preventing backsiphonage, the pressure vacuum breaker also serves the purpose of isolation. This means that it can be installed to protect a specific zone or fixture from potential contamination while allowing for the safe use of water in that area. This ability to isolate parts of the water system adds an extra layer of protection against the introduction of harmful substances.

In contrast to other applications, the PVB does not address backpressure, which is a different scenario where pressure in the system causes potential backflow of contaminants due to a higher pressure upstream. Similarly, it doesn't focus on pressure stabilization or filtration, nor is it used for pressure reduction. These functions are addressed by other types of backflow prevention devices or plumbing configurations.