Nidel Model 34HD Anti-Siphon Vacuum Breaker
From Free Knowledge Base- The DUCK Project: information for everyone
The 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. Also referred to as a Model 37HD1 Backflow Preventer it is designed for freezing areas only.