Factors that should be considered befor selecting an ultrasonic flow meter
The most commonly used ultrasonic flowmer is transit-time based single-path flowmeter due to its high accuracy and reasonable cost.
Depending on the applications, the selection of the right type of flowmeter may vary. You may need to answer the following questions before making the final decision:
Is the pipe full?
All ultrasonic flowmeters require that the pipe is full of liquids. There are some work around with partially full pipe, but by no means you will get good results.
Does the liquid have particles more than 200ppm and particle size larger than 75um (the number may be different for different manufacturers).
If yes, use Doppler. Otherwise, consider transit-time.
Does the liquid temperature fall into the transducer temperature range?
Pressure range in the pipe (if you select wetted transducer)?
High accurate the measurement should be?
In general, multi-path is higher than single path, flow cell is better than insertion, and insertion is better than clamp-on. However, if you have on-site calibration facility, the story will change.
Do you want to easily move the flowmeter around?
What output signals you need? What functionalities you want?
Analog? Digital? RS232? Data logger?
What are the safety requirements?
Pipe size range? Pipe material? Lining?
Flow rate range?
Enough straight pipe length?
In order to guarantee the result accuracy, it is normally recommended to have 15 times of pipe diameter straight pipe run at the measuring site.
If there is a pump or valve on the upstream, the straight length should be increased.
The financial budget?
The above questions seem overwhelming if this is the first time you are looking for an ultrasonic flowmeter.
Please do not be scared. Most likely, a simple clamp-on transit time handheld flowmeter or wall-mount flowmeter will suit your application.
If not, please feel free to contact us for detailed suggestions.