Flow sensor or flowmeter?

flow sensor

Flow sensor or flowmeter, that’s the question 😉

To be honest, when we would be having a conversation about your application, it doesn’t matter wether the needed instrument is referred to as flowmeter or flow sensor. We will both know what we mean and come to the right conclusion.

A different situation is the moment that an engineer starts searching the internet for a flow sensor. Chances are high that the search result returns a sensor which has no proper measuring capability. A disappointing testresult is to be expected.

When to choose for a flow sensor?

Flow verification

A flow sensor will return a signal when flow is detected. So if you look for a flow-verification, a sensor is sufficient. You may have already a signal that the pump is running, but due to numerous aspects in the piping system, it is well possible that the intended flow is not happening. A simple sensor will provide certainty!

High-Low flowrate

In your system there might be situations where a high or a low flowrate occurs, a sensor might be ccurate enough to properly determine which of the stages is actual. Again a good sensor-application.

When is a flowmeter the better option?

Input for a controlled flow

In equipment there are often liquid cooling circuits in which a nominal flowrate is designed. In process-circumstances the actual flowrate may differ from the nominal value.
The actual flowrate is converted in real-time to an analogue value (often 4-20 mA range).
This signal acts as a reference for adjusting the pump.
The result is a flowrate that is continuously at the designed value, providing maximal thermal stability to the equipment.
MIB’s Flowmax 44i is a commonly used instrument in piping up to Dn25 m.
Higher flowrates are handled by Flowmax 54i.

Qualification of a pump

Imagine your engineers designed a new setup which will be the basis of all your machines in the future.
Do you trust the specs on paper, or would a validation make sense? In most industries qualification and validation are mandatory.
A test-bench with an accurate flowmeter is part of that.

Volumetric / Batch-control

In applications where a certain volume needs to be dispensed or transported, a flowmeter is the right instrument to measure the volume which has passed.
Flowmax has the option to define the batch-volume and when this amount is measured, a digital output signal informs the system that valves can be shut and pumps turned off.

Volumetric control for financial transactions

When purchasing fuel, the dispenser registers the amount of dispensed.
The measured volume is used to initiate the financial transaction.
The instrument to use here is not a flowensor and not a normal flowmeter, it requires MID-approval.
Flowmeister is happy to advise you on this topic!
Sorry we can’t fill it in with the range of Flowmax instruments.

What’s your application? Get advised and receive a quote !

Your instrument has been tested, which is certified with the delivery. Optionally, a 3- or 8-point calibration-certificate can be ordered to prove the exact accuracy.

Before you submit:

you may trust an honest advise. If FlowMax is not your best possible solution, I will explain you why that is.

Flowmax products

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Trust by design

When asked what is the most important property of flow measurement, almost every customer answers “ACCURACY”.
Understandable, you would rather not invest in an inaccurate instrument to control your pocess.

When the conversation continues, very often it appears that the automated production system is not too dependent on accuracy of the flowmeasurement itself.
The product-quality is more influenced by process-aspects that cause wrong readings coming from the meter.
In certain circumstances, it appears that the readings cannot be trusted.
The design of Flowmax ultrasonic flowmeters is made to be trusted.

Reliability is the key …

Some physical examples of improved reliability:
– An open bore without obstacles is never causing disturbances, cavitation
– No moving or rotating parts in the liquid which may wear out or get stuck
– Moving or rotating parts may release particles in the liquid
– No gaps, dead space or seals to affect product quality or leakage
– Air bubble detection immediately warns for detected bubbles
– Robust measuring tube, physically stable measuring unit
– Solid sensor mounting, not sensitive to environmental vibrations

All reliability features apply equally to Industrial and Single Use versions!

… and Accuracy matters

Of course accuracy matters.
Third to Reliability and Speed, the measuring accuracy is one of the selling features of Flowmax ultrasonic flowmeters!
Our biggest advantage is the fact that the calibrated measuring tube is inserted into your flowpath.
Calibration data is stored in the measuring tube.
This simple fact ensures that the performance in your system is comparable to the performance in the manufacturers’ calibration setup!
What else would you need?

What makes your application special?

Your instrument has been tested, which is certified with the delivery. Optionally, a 3- or 8-point calibration-certificate can be ordered to prove the exact accuracy.

Before you submit:

you may trust an honest advise. If FlowMax is not your best possible solution, I will explain you why that is.

Repeatability vs reproducibility


A short blog about terminology which is often used when flowmeter specifications are discussed.

The quality of the instrument is easily verified by doing a number of repeated measurements and comparing the measured values.
A robust measurement concept will prove the multiple readings to be close to each other, there is little to no variance.
The flowmeter then has a high repeatability, which is a positive aspect.

An ultrasonic flowmeter has no moving parts which inherently adds to the repeatability when compared to a turbine-meter where overspin and start-stop behaviour leads to variances.

What about reproducibility

Sometimes the term reproducibility is mentioned, this is a correct word, with a very different meaning than repeatability.
Reproducibilty indicates how succesful a different person can obtain similar results from the same flowmeter.
Again here a turbine-meter is more sensitive to the piping and orientation which reduces the chance that readings will be exactly the same in a random setup.

The mix-up of the two terms is often heard in Dutch-speeking countries, which is not a coindence.
The Dutch translation of repeatability is reproduceerbaarheid, often mixed up with reproducibility.

Is repeatability relevant for flowmeister

Flowmeister uses repeatability the way it was intended.
The open bore instrument with no moving parts proves repeatable, time after time after time.


Our single use instrument-range (Flowmax 242i) shares all design features which make the industrial instruments reliable and repeatable.
This includes a full calibration, ensuring a trusted operation, no matter if it is for hours, days or years!

Reproducibility matters as well.

Our different customers all experience good performance of the flowmeter.
Either in chemical, semi-conductor or OEM-industry, the results are good.
This is an example of reproducibilty.

More about repeatability and reproducibility can be read here.

React to this post

I hope the above gives clarification between two terms.
Clarification and better understanding lead to less mix-up in your daily flow-business.
Let me know if further questions or remarks pop up.