. Chemical weed-control equipment. Weeds; Spraying; Spraying equipment. erally made in several sizes, with various pressure and discharge rates. These rates are always included with each pump and engine unit. If information is given for the pump alone, pressure and discharge rates for the various speeds will be shown. With the positive displacement type, such as the plunger pump, the dis- charge in gallons per minute at maximum pressure is about the same as the dis- charge at zero pressure. However, for a centrifugal pump, the discharge at maxi- mum pressure is much less than that at zero pres
. Chemical weed-control equipment. Weeds; Spraying; Spraying equipment. erally made in several sizes, with various pressure and discharge rates. These rates are always included with each pump and engine unit. If information is given for the pump alone, pressure and discharge rates for the various speeds will be shown. With the positive displacement type, such as the plunger pump, the dis- charge in gallons per minute at maximum pressure is about the same as the dis- charge at zero pressure. However, for a centrifugal pump, the discharge at maxi- mum pressure is much less than that at zero pressure. Regenerative turbine and flexible impeller pumps follow much the same discharge pattern as the centrifugal, while rotary gear and other rotaries have characteristics somewhere between those of the centrifugal and the plunger types. The water horsepower equation can be used to find the approximate power needed for a given pump: Hp lbs. pressure x 9pm 1730 x efficiency Pump tests indicate the efficiency will vary from 20 to 80 per cent, depending upon the pump type and size. Efficiency information can be obtained from the pump manufacturer. Small pumps on weed sprayers are generally very low in efficiency. When figuring horsepower, it is better to use a low figure for efficiency, which will result in an engine with some excess Power for the pump may be supplied by auxiliary engines or by a power take-off drive from a tractor. For a power take- off-driven spraying unit, the pump may be mounted on the tractor, while the tank and boom are on a trailer, or pump, tank, and boom may be carried on the tractor, as shown here. When this plan is used, the pump is either driven directly from the power take-off, or from the belt pulley. NOTE: A spray unit with an auxiliary en- gine has an advantage over the power take-off because the auxiliary's speed can remain constant regardless of changes in the tractor's speed. The im- portant factor in choosing either type is to select a
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Keywords: ., bookcentury1900, bookpubli, booksubjectspraying, booksubjectweeds
