A separate throttling valve is usually used to control agitation flow and spray pressure. Spray pressure can be controlled by a throttling valve, eliminating the pressure relief valve with a separate bypass line. The flow from centrifugal pumps can be completely shut off without damage to the pump. This permits controlling agitation flow independent of nozzle flow. Two control valves are used in the pump discharge line, one in the agitation line and the other to the spray boom. A strainer located in the discharge line protects nozzles from plugging and avoids restricting the pump input. The proper way to connect components on a sprayer using a centrifugal pump is shown in Figure 3. Also, no pressure relief valve is needed with centrifugal pumps. Pumps may also be driven by a direct-coupled gasoline engine, which will maintain a constant pressure and pump output independent of vehicle engine speed.Ĭentrifugal pumps should be located below the supply tank to aid in priming and maintaining a prime. This allows the PTO to be used for other purposes, and a hydraulic motor may maintain a more uniform pump speed and output with small variations in engine speed. Centrifugal pumps can be driven by a direct-connected hydraulic motor and flow control operating off the tractor hydraulic system. The gears are completely enclosed and mounted directly on the PTO shaft. Another method is to use a planetary gear system. A simple and inexpensive method of increasing speed is with a belt and pulley assembly. When driven with the tractor PTO, a speed-up mechanism is necessary. Centrifugal and roller pump performance.Ĭentrifugal pumps should operate at speeds of about 3,000 to 4,500 revolutions per minute (RPM). Roller or rotary pumps with rolling vanesįigure 2.Pumps used on agricultural sprayers are normally of four general types: Other things to consider are initial pump cost, pressure and volume requirements, ease of priming and power source available. The materials used in pump housings and seals should be resistant to chemicals used, including organic solvents. Pumps should be resistant to corrosion from pesticides. This will allow for agitation and loss of capacity due to pump wear. A pump should have a capacity of at least 25 percent greater than the largest volume required by the nozzles. A pump must have sufficient capacity to operate a hydraulic agitation system, as well as supply the necessary volume to the nozzles. The type and size of pump required is determined by the pesticide used, recommended pressure and nozzle delivery rate. A change of nozzles may be required, which can affect spray volume and system pressure.
#The signal state tractor gear system manual
Consult the operator’s manual for detailed information on a particular sprayer.Īsprayer is often used to apply different materials, such as pre-emergent and postemergence herbicides, insecticides, and fungicides. It is extremely important to observe safety precautions, wear protective clothing when working with pesticides, and follow directions for each specific chemical. Improperly used agricultural pesticides are dangerous. Dry flowables may wear nozzle tips and may cause an increase in application rates after spraying as little as 50 acres.
Equipment should be recalibrated periodically to compensate for wear in pumps, nozzles, and metering systems. A study in another state found that four out of five sprayers had calibration errors and one out of three had mixing errors.Īpplicators of pesticides need to know proper application methods, chemical effects on equipment, equipment calibration, and correct cleaning methods. Several were in error by 30 percent or more. A North Dakota study found that 60 percent of the applicators were over or under applying pesticides by more than 10 percent of their intended rate. Studies have shown that many application errors are due to improper calibration of the sprayer. The high cost of pesticides and the need to protect the environment are incentives for applicators to do their very best in handling and applying pesticides. Improper or inaccurate application is usually very expensive and will result in wasted chemical, marginal pest control, excessive carryover, or crop damage.Īgriculture is under intense economic and environmental pressure today.
Properly applied pesticides should be expected to return a profit.
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