Passive automatic quantitative feeder

The utility model relates to a device in which the rainwater purification is implemented through the flowing of officinal liquid, which is composed of a medicine tank, a quantitative water tank, a reaction can, a siphon valve combined from a brass and a rubber membrane. An ejector valve is disposed in the medicine tank and the quantitative water tank communication tube. A siphon valve is disposed in the quantitative water tank, and the vents of the quantitative water tank and the reaction can are covered by the rubber membrane of the siphon valve. An inverted U-shaped brass is disposed on the top of the siphon valve. A synchronous float ball sliding along the pipe wall is installed on one side pipe of the brass, which is opposite to the ejector valve. The synchronous float ball and the ejector valve are in the same center line. The utility model is with no power, no electricity and no need of duty, which is automatic. The water is controlled through the siphon valve, and the dosage quantitative is controlled through the float ball and ejector valve. The utility model is quantitative. The quantity of dosing is controlled through the ejector valve flow, and the treating water quantity is controlled through the volume of the water tank. The utility model is applicable for rural water treatment, cellar water purification and dosing control of water supply projects, which is favourable for promoting with low costs and convenient operation.