Liquid Chromatography - The Twin-Headed Pump 2
Figure 9. The Twin-Headed Pump
The cams are carefully designed to produce a virtually pulse-free flow. The displacement volume of each pump can vary from 20 or 30 microliters to over one milliliter but the usual displacement volume for the typical pump is about 250 ml. The pump is driven by a stepping motor and thus the delivery depends on the frequency of the supply fed to the motor. As a consequence, the pump can have a very wide flow rate range from a few microliters per minute to over 10 ml per minute.