The dual check valve with atmospheric port, also known as a vented dual check valve, is a protective plumbing device capable of preventing
backflow of polluted water into the mains water system. This type of backflow may occur due to changes in pressure in the distribution network
that cause water to flow backwards. The preventer, which is fitted between the mains and the user system in water distribution systems, creates
a safety separation area that prevents any contact between the water in the two systems.

The Caleffi 573506 series dual check valve with atmospheric port is a low hazard device. Most commonly used for underground rainwater tanks,
as well as dental chairs, hairdressers, combi ovens, however, this varies with local regulations, therefore the application much be checked with
the water authority before installation.