A flushometer must have what device placed above the fixture?

• A. Check valve
• B. Vacuum breaker
• C. Air gap
• D. Pressure reducing valve

Answer: (B)

The concept being tested is backflow prevention in a flushometer setup and why a vacuum breaker is used above the fixture. A flushometer can create rapid pressure changes that might pull water back into the building’s potable supply if a vacuum forms. A vacuum breaker provides an air intake path when a vacuum starts to form, breaking the siphon and preventing backflow into the supply. Placing it above the fixture keeps the vented path accessible and effective, so contaminated water cannot be drawn back through the supply line. The other options don’t serve this protection in the same way: a check valve blocks reverse flow but doesn’t vent a siphon; an air gap is a separate backflow method not specifically tied to the flushometer’s location above the fixture; a pressure reducing valve only lowers pressure and doesn’t address backflow prevention.