As discussed in Section 2  Part 3, the viscosity and specific gravity for some chemicals can vary greatly with temperature changes. If you have this information on hand, please use the maximum specific gravity and viscosity of your chemical in the pump selection criteria. This value is usually associated with the minimum temperature limit of your application. For example, if your pump application is outdoors and with insulation, the expected ambient operating temperature may vary between 10~30 ℃, then you use the physical characteristics at 10 ℃. If you do not have the physical properties available, contact the pump manufacturer and they may have the information in their database.

Since a higher S.G. and/or viscosity will result in a heavier load, there are generally two approaches to adjusting the pump for the application.

First, if there is room between the performance (H-Q curve) of the pump and your desired duty point, then you can lower the performance curve by either reducing the speed of the motor via a Variable Frequency Drive (VFD) or if a VFD is not planned, you may discuss the option of trimming the pump’s impeller with the manufacturer.

Second, if the pump selection software is still showing the required power of the application is still above the rated power of your motor, then the only option is to move up to the next available motor size. In some instances, the pump selection may also change accordingly.

It is highly recommended that you have the pump manufacturer check your pump selection after adjustments since there may be some other limitations that are not immediately apparent.