Four new images added to InterNACHI's Inspection Image Gallery: Backflow Preventers

https://www.nachi.org/gallery/piping/pressure-vacuum-breaker-backflow-preventer

and

https://www.nachi.org/gallery/piping/double-check-valve-assembly

and

https://www.nachi.org/gallery/piping/atmospheric-vacuum-breaker-backflow-preventer

and

https://www.nachi.org/gallery/piping/reduced-pressure-zone-backflow-preventer