Pump selection begins by determining the flow rate required. In most cases, this is determined by the size of the liquid outlet on the tank feeding the pump. Motor speed is an important factor in selecting the correct pump for your specific application. Continuous duty pumps should be operated at slower than maximum drive speeds. If this is the case, a slightly larger capacity pump may be selected and driven at a slower drive speed to match the flow rate required. The pump speed, differential pressure requirements, and temperature will determine the flow rate and horsepower requirement.
The NSSA Option
If the pump will be operated between 2-24 hours continuously or started and stopped many times within this time frame, specify the NSSA option. Also, the pump should be operated at less than the maximum rated speed. One-half the maximum rated speed is recommended.
The "L" Option
For pump models rated between 20-200 GPM, the pump rated capacity can be increased by specifying the “L” option. This will increase the rated transfer capacity by almost 20%. When using the formula to determine the actual delivery rate, use the rated pump transfer capacities as shown in the table, PLUS 20% of the shown capacity. As an example, if an MC-2 pump is selected (50 GPM rated transfer capacity), this pump utilizing the “L” option is now rated for 20% higher capacity, or 60 GPM. Use 60 GPM as the rated transfer capacity when using the formula. The “L” option is not available for MC-2H, MC-3H, MC-4H, MC-5H, ATC-2H, ATC-3H type pumps.