Selecting the right flow meter can in many cases simplify and reduce the cost of maintenance in a minerals processing plant, as well as save valuable time during plant stoppages. Furthermore, the correct selection of flow monitoring equipment is a key aspect of operation and process control required to maximize plant efficiency and throughput. Flow meters must be selected carefully based on the frequency of required maintenance, type of liquid flowing through the pipe, the liquid’s properties (abrasive, corrosive, prone to scaling, etc.), whether or not the flow meter needs to be relocated frequently, whether or not the pipe needs to be replaced frequently, the desired accuracy of the measurement, as well as the meter’s reliability, ease of installation, portability, etc. The overabundance of available technologies and marketing hype can make this a challenging process, which is made only more difficult by a lack of literature on the subject.

This paper will only review non-invasive flow meter technologies (time of flight ultrasonic, Doppler ultrasonic, and array-based sonar), their maintenance requirements, and their pros and cons when installed on challenging applications in the process plant. An explanation of the functioning principles will be given, as well as the strengths and weaknesses of each technology. Finally, examples of ideal applications for each technology will be provided.

This paper aims to help the plant operator correctly select the appropriate technology for a particular process application, while outlining the criteria considered, and simplifying the selection process for any application. The reader will come to understand the many maintenance benefits of non-invasive technologies, such as reduced down time, little to none maintenance requirements, low installation and lifecycle costs, and ease of installation and use.