Variable Flow Controllers for Manure Application

The most popular way to spread swine manure in Illinois is by using a slurry tank. It is difficult to estimate or control the rate of manure application when using soil injection equipment. An economical variable rate control system is needed for both new tanks and to retrofit the large number of tanks already in operation on farms. The proposed control system consists of a pneumatically operated variable wastewater valve constructed of a cast-iron or aluminum case with a rubber hose insert. Flow measurement will be accomplished through differential pressure readings based on experimentally calculated flow rates. A resultant curve of differential pressures vs. flow rate was found to characterize the valve. By maintaining a certain differential pressure through a control system, the flow rate through the valve can be determined.