Which statement accurately describes PVB use in backflow prevention?

Which statement accurately describes PVB use in backflow prevention?

• A. PVBs are not used for backflow prevention.
• B. PVBs protect against backsiphonage only.
• C. PVBs protect against backpressure only.
• D. PVBs protect against backsiphonage and backpressure equally.

Answer: (B)

Pressure Vacuum Breakers are designed to protect the potable water supply from backsiphonage in irrigation and similar systems. They have an atmospheric vent that opens when supply pressure drops, admitting air and breaking the siphon so contaminated water cannot be drawn back into the supply. They do not provide protection against backpressure, because they cannot resist water flowing back toward the supply when downstream pressure is higher. For backpressure scenarios, a more robust backflow preventer (such as an RPZ or a double-check with relief) is needed.

Pressure Vacuum Breakers are designed to protect the potable water supply from backsiphonage in irrigation and similar systems. They have an atmospheric vent that opens when supply pressure drops, admitting air and breaking the siphon so contaminated water cannot be drawn back into the supply. They do not provide protection against backpressure, because they cannot resist water flowing back toward the supply when downstream pressure is higher. For backpressure scenarios, a more robust backflow preventer (such as an RPZ or a double-check with relief) is needed.