571--CHK-A Fix failed leaky RV vacuum breaker valve on black tank flush system line when black tank flush line system was blocked or faulty and leaking, causing wet RV trailer floor. Exact vacuum breaker check valve RV replacement for cracked and leaking RV check valve. If your RV vacuum breaker check valve is leaking during black tank flushing, simply replace the RV black tank flush check valve. It is a perfect vacuum valve for RV black tank flush. A part of the black tank flushing system that installs between the freshwater inlet connection and the tank flusher. The vacuum breaker for RV black tank flush helps mix black tank water with grey water. RV backflow preventer keeps freshwater source clean and healthy. The black tank anti-siphon valve or vacuum breaker is designed to prevent contents from the black tank from siphoning back into the RV water supply. Prevents contamination of water supply from backflow and back-siphonage. Working water pressure range: 8-125 PSI. Connection type: 1/2 inch NPT male threads on both inlet and outlet. Color: Black. Material: ABS. Package contents: 1 x RV Vacuum Breaker Check Valve. Only the above package content is included; other products are not included. Note: Light reflection and different displays may cause the color of the item in the picture to appear slightly different from the actual item. Measurement allowance is +/- 1-3 cm.