Flow Meter & Dosing Pump Combinations

• Flow controllers can automatically correct a dosing pump for inaccuracies caused by temperature and pressure changes, air entrapment, and wear of components
• A flow meter alone won’t correct the pump, so opt for a flow meter with an integrated PID controller
• Offers fast response time for quick corrections to help reduce cost of operation and waste

Traditionally, a dosing pump, 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.

Improve Dosing Pump Accuracy with Flow Meter and Controller

Inaccuracies like this are caused by many changing process conditions, such as:

• Temperature
• Pressure shifting
• Air entrapment
• Wear of components 

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.

Ultrasonic Flow and Coriolis Flow Meters and Controllers

Such effects can be avoided by using a Bronkhorst ES-FLOW flow meter and controller or mini CORI-FLOW flow meter and controller to directly control the pump. 

Flow Meter with Integrated PID for Direct Pump Control

By only adding a mass flow meter or volume flow meter to your process, you will not get the best solution as you still need an additional PID controller to drive a pump and 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.

Automated Corrections for Dosing Pump with Fast Response Time

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 the desired flow and the black box generates this flow for you, stable and with a high accuracy as well. 

Benefits of Using a Flow Meter to Correct a Dosing Pump

• Less waste & cost reduction: You know what you pump in real-time.
• Less down time: Fluid independent flow measurement and control – no need for recalibration when changing fluids.
• Real measurement of data on flow performance for quality and monitoring purposes, including a response alarm.
• Automatic correction for decreased pump performance over time.
• Correction on ambient conditions that have an influence on your physical properties of the fluid.
• Integrated PID controller for fast and accurate flow control.
• Remote communication with the control loop via Bus protocol.