34HD - Freezing Temperatures are Expected
37HD1 - Freezing and Non-Freezing Conditions.

The Woodford NIDEL® Model 34HD anti-siphon vacuum breaker is designed to protect hose connections from contamination where freezing temperatures are expected. Manual draining provides easy sure drainage during cold weather.

The Woodford NIDEL® Model 37HD1 hose connection backflow preventer isdesigned to protect hose connections from backflow contamination in freezing and non-freezing conditions. Manual draining is required and provides easy sure drainage during freezing weather.

Uses include outside hose bibbs wash racks dairy barns and swimming pool areas.

Available Finishes:
Chrome Plated and Brass
 

NOTICE:These products as with all 1011 1019 1052 and 1053 ASSE listed devices are not to be subjected to continuous water pressure. Replacement is recommended every 3-5 years. After use turn device to open drain vents or faucet may freeze and burst.