Anti-siphoning device for venting drain lines

摘要

The anti-siphoning device includes a T-shaped valve body having a downwardly facing opening, an upwardly facing opening and a laterally facing opening. Constrained for vertical movement within the valve body is a hollow cylindrical float valve having a closed lower end for normally closing the lower opening of the valve body, an open upper end so that air can pass downwardly through the upwardly facing opening of the valve body into the interior of the cylindrical float valve, out through the circumferentially spaced holes and then through the laterally facing opening of the valve body. The downwardly facing opening of the valve body is connected to the outlet of the sink or basin to be drained. Waste water entering the valve body via the downwardly facing opening buoys the float valve upwardly, the water passing outwardly through the laterally facing opening along with the air entering the upwardly facing opening of the valve body. When no waste water is flowing, then the weight of the float valve seals against an annular seat innerjacent the downwardly facing opening of the valve body so that sewer gases will not flow upwardly past the float valve. Also, an air valve is located in the upper portion of the valve body, the air valve normally preventing air from entering the valve body but permitting air to enter when a reduced pressure exists within the valve body due to the flow of waste water upwardly through the downwardly facing opening and outwardly through the laterally facing opening.