Watts 0556031 Water Service Vacuum Relief Valve 3/4" N36

The Watts 0556031 Water Service Vacuum Relief Valve N36 is a plumbing part that helps in safeguarding the water system against negative pressure situations that may cause contaminants to be forced into the potable water system. It works by opening to allow air to enter when a vacuum or partial vacuum is created after which it closes when the normal pressure is restored. The 3/4 inch NPT connections are used to install the valve on the service line at the point of protection which is usually the meter or main shut-off.