The pump is the heart of a spraying system. It is used for several operations, each of which may require a different flow rate. Select a pump with a capacity to handle the highest application rate. Select a pump with a reserve capacity at least 20 percent greater than the sum of the requirements for the largest volume sprayed to compensate for a possible reduction of the flow rate in the future because of wear. The type of chemical sprayed also affects pump selection.
Some pumps handle abrasive materials like wettable powders with much less wear than others.
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.