Actually, there is no such thing as ‘best’ flowmeter.
Chemical resistance is a relative aspect, since there’s a huge number of chemicals.
Besides that, ‘best’ will usually include more aspects than just chemical resistance.
Flowmeister BV concentrates on non-metal flowmeters and is able to propose one or more suggestions for each chemical application.

This blog is far too short to zoom in on each of the possible selection-criteria and the multiple ways to meet these criteria.
Therefore we will highlight the most common aspects and give examples of solutions.
Chemical resistance is the first and most important aspect in the context of this blog.
Secondly, we will address accuracy, viscosity and cost.

When your process involves a chemical, it is obvious that the hardware will need to be chemically resistant.
For reasons of safety and reliability, the material selection matters most of all.
To determine which selection of instruments can theoretically deal with the chemical, Flowmeister BV uses an extensive table with hundreds of chemicals.
This table shows the performance of 2o engineering plastics to each chemical.
Often the temperature and concentration affect the outcome, therefore we will always ask for the temperature-range of your process.

The outcome of this screening is usually one of more preferred materials, for example PFA.
With this basis, and the known flowrange, a first selection in the folder of datasheets brings forward the commercially available options.

Form the shortlist of possible instruments, we determine the overall ranking, considering properties like accuracy, viscosity and cost.
Accuracy and viscosity go hand-in-hand. Physics is the most absolute aspect and comes first.
For water-like liquids with a low viscosity, a turbine-meter is a good and economic solution. More viscous liquids will require an ovalgear flowmeter, or will work well in an ultrasonic instrument.
If your process requires an overall accuracy within 2% of measured value, we have more capable instruments to chose from. This selection get smaller when we need to meet a 1 or 0.5% allowed deviation.
Cost is less absolute and is a consequence of previous needs.
Whatever the cost is, you may trust it’s the best outcome, based on hard demnads as chemical resistance, measuring-range and accuracy.
Is the needed investment too high? Please consider a different accuracy and implement an in-situ calibration.
The cost of that needs to be compared to the CAPEX-investment of course……

To conclude, we’d like to refer to some recent solutions.
In general, the ultrasonic Flowmax® flowmeters are well-received in chemical dosing systems.
A robust design and a wide coverage of chemicals with the selectable materials such as PFA, HDPE 500, PSU and PP.
Interesting feature is the default analogue and pulse-output signal.

For liquids with low viscosity and in lower flowrates, the Digmesa turbine-meters are a cost-efficient solution. The chemical versions have no metal wetted parts, but there is a seal, which could introduce a risk-factor.

In the micro-fluidic range, the thermal flowmeters of Biotech Fluidics serve applications from nearly 0 up to 650 ml/minute. 

With a chemical resistance issue in mind, never guess that the most expensive instrument will automatically  be the ‘best’.
Contact Flowmeister BV and get an objective advise, which includes the points of attention.