The semiology of graphics

A liquid proportioning system includes two groups of positive metering tanks, each group consisting of at least two tanks each containing a supply of liquid to be blended and including outlet control device for selectively regulating the volume of liquid leaving the tank per unit of time. The liquids from each tank are fed together through a single conduit to a mixer which continuously blends the liquid components as they are flowing, and the blended liquids are fed to a reservoir tank, from which they are fed to a point of use in accordance with the variable requirements of the latter. One group of positive metering tanks feeds the liquid components to the mixer in exact proportions until these tanks are depleted, at which time the flow from these tanks is shut off automatically and the second group of tanks begins to feed the portioned liquid components to the mixer, while the first group of tanks are refilled. When the requirements of the point of use are decreased, sensors slow down the feeding of the liquid to the reservoir tank by increasing the time interval between the emptying of one group of metering tanks and the commencement of feeding from the other group of tanks.