Chemical reaction and corrosion affect some pump materials. Another important consideration in pump selection is the pump's pressure rating. The pump should produce a desired operating pressure at the capacity required for specific spraying jobs. Some pumps are capable of delivering the desired flow rate at various operating pressures, figure 1, while others cannot. Also, forcing a low pressure pump to produce high pressure causes it to wear out rapidly.
Some pumps require faster speeds than a standard farm tractor PTO can provide.
Use an auxiliary power source or a speed increase to achieve optimum performance. Pumps A pump is either a positive displacement or nonpositive displacement type. A positive displacement pump discharges a specific volume of liquid with each stroke or revolution. A positive displacement pump also draws a low vacuum and, therefore, does not require filling the pump or placing it below the tank level to prime it. Piston, gear, and roller type pumps are positive displacement pumps.