Flow meter & Pump combinations
Why do you need a mass flow meter or volume flow meter if you have a dosing or metering pump?
Traditionally, dosing- or metering pumps are believed to be accurate. For every rotation of the pump, the pump head will displace a known volume of a liquid. This results in a known pumped volume over time based on the amount of rotations. In practice however, it appears to be difficult to achieve a high level of accuracy. A deviation of a few percent is not exceptional. Why?
Inaccuracies like this are caused by many changing process conditions, such as:
One or more of these factors can impact the amount of liquid being displaced with each pump head rotation, resulting in a small inaccuracy. However, this can result in quite a large flow deviation when having multiple rotations in a period of time.
Such effects can be avoided by using a Bronkhorst ES-FLOW or mini CORI-FLOW flowmeter directly controlling the pump.
Ultrasonic volume flow meter with pump
This video explains the principle of operation of the ultrasonic volume flow meter and how the flow can be adjusted through the combined used of a ultrasonic volume flow meter and a gear pump.
Coriolis Mass Flow Meter with pump
This video explains the mechanism of a Coriolis mass flow meter and how the flow can be adjusted quickly and precisely through the combined use of a Coriolis mass flow meter and a gear pump.
Integrated PID for direct pump control
Just by adding a mass flow meter or volume flow meter to your process, you will not get the best solution as you still need an additonal PID controller to drive a pump to achieve the desired dose or flow. The PID controller is used to compare the real flow signal with the desired flow. The Bronkhorst Coriolis mass flow meters and ultrasonic volume flow meters have an integrated PID controller. So, by using these instruments it is not necessary to add an additional PID controller. You do not have to include the pump in the control system anymore, you just give a set point demand to the flow meter and it will drive the pump to the desired flow. The big advantage here is that the mass flow meter or volume flow meter use a high frequency signal, which makes this way of controlling the pump much faster than the traditional way of pump control.
It's like a black box: You indicate your desired flow and the black box generates this flow for you, stable and with a high accuracy as well.