Importance

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Abstract

A system and method for metering the application of liquid agricultural chemicals to the soil from a moving vehicle at a substantially constant preselected application rate, e.g. gallons per acre, substantially independent of vehicle speed. The system uses a centrifugal pump driven at a rate substantially linearly proportional to vehicle speed and having its outlet pressure substantially proportional to the square of its speed. The pump receives liquid from a supply tank and delivers it to liquid discharge orifice means the rate of flow through which is substantially proportional to the square root of the pressure thereon. The system also includes a line having adjustable orifice means therein controllable by the vehicle driver while the vehicle is moving for returning a portion of pump delivery liquid to the tank and controlling upstream pressure. Orifice pressure Pn required to achieve a preselected application rate at a selected vehicle speed can be determined readily. For each such Pn there is a corresponding calculable, or ascertainable by test, pump system pressure Pc when flow to the discharge orifice means is shut off. A Pc pressure gauge is readable by the driver and also preferably a Pn gauge. Pn is first determined and then the corresponding Pc. The vehicle is moved at the selected speed with the pump being driven and flow to the discharge orifice means shut off while the driver adjusts the adjustable orifice means to preset the Pc corresponding to the determined Pn. Flow to the discharge orifice means can then be started to obtain substantially the preselected application rate at substantially all vehicle speeds.

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First Claim