Combination of mini CORI-FLOW with Tuthill pump
How does pump control work?
Flow generated by a pump is volumetric flow with all characteristics that come with this. The accuracy will be heavily depending on the fluid properties, making the flow temperature and pressure dependent. Furthermore, most pumps cannot handle a fluctuating back pressure as this creates slip, instability and a high deviation in flow rate.
A method to improve the accuracy is by measuring the flow of the pump with a flow meter, since these instruments measure the flow produced by the pump. The output of the meter is often connected to a PID controller which in turn corrects the frequency of rotation (RPM) of the pump.
A disadvantage of this method is that the flow of a pump is not stable which makes filtering of the Coriolis output signal necessary, causing a slow output signal. Because this signal is used as control signal as well, the result will be a slow response and slow control.