| 摘要 |
A sprayer mixes water and concentrate on an "as-used" basis. A preselected amount of concentrate is dispensed into a mix tank for each reciprocation of a proportioning pump set. The amount of concentrate dispensed is selected by varying the pump set stroke. The pump set is reciprocated by reversing flow into one power line and out of another power line fluidly connected to the set. The flow is reversed by sliding a spool within a bore from one position, where sets of apertures in the spool are aligned with ports of the bore to connect a source of water under pressure to one power line and the other power line to an outlet line leading to the mix tank, to another position, where the aperture sets are realigned with the ports to reverse the connections. A meter measures the flow of water to the mix tank. The meter connects current to open one of two control valves connecting the bore ends with the source to move the spool to its next position hydraulically. The meter switches current from one control valve to the other when a unit amount of water flows to the mix tank. The amount of concentrate dispensed for each reciprocation is in a desired mixture proportion to two unit amounts of water. A high pressure pump pressurizes mixture from the mix tank, which is discharged through a spray gun, or recycled in part to the mix tank to agitate the mixture therein.
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