This device is a dispenser for a measured amount of liquid, bleach, water softener, etc., into a toilet tank with each flush. The valve works on the principal of differential densities between water and the valve shuttle. The volume dispensed is the volume of the cavity formed by the valve shuttle and the base of the unit. When the toilet is flushed the water level goes below the level required to float the valve shuttle which lets it drop and dispenses the liquid contained in the valve reservoir. This motion closes the valve inlet with the conical upper end of the valve shuttle. The angle of the cone is designed to shed air bubbles from the now empty valve reservoir. When the tank refills the water will cause the valve shuttle to rise shutting off the dispensing reservoir from the tank and opening it to the liquid reservoir. The lower end of the valve shuttle is spherical so it will form a seal with the tapered seat regardless of the valve shuttle’s attitude in the up position.
The empty weight is greater than the water displaced by the unit in the toilet tank to keep it from floating when empty. The offset feet keep the unit slightly tilted so it remains against the tank wall. The construction materials are a suitable plastic for the valve shuttle, stainless steel and zinc alloy. The total cost of manufacture in the US was planned for a retail price of about $23 in volume.