The patented Nidel® Model 50H high flow double check backflow preventer is intended for irrigation purposes and designed to protect hose connections from backflow contamination in freezing and non-freezing conditions. The Nidel® Model 50 high flow double check backflow preventer automatically drains when the hose is removed and unlike single check vacuum breakers can be field tested for reliability. Uses include outside hose bibbs, wash racks, dairy barns and swimming pool areas.