Flow rate meters for ventilation adjustment

Flow rate meters, also called balometers, are analogue or digital instruments for measuring flow rates during the testing, balancing and commissioning of ventilation systems in buildings. ACIN instruments has two volume flow meters (balometers). These are the FlowFinder-mk2 and the VentiFlow-mk2, both developed and produced by ACIN instruments.

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How does a flow meter work?

The Flowfinder-mk2 and the Ventiflow-mk2 are air volume flow meters, but they have different measuring principles.

The Flowfinder-mk2 uses zero pressure compensation. The resistance that the incoming or outgoing air experiences when measuring with a Flowfinder-mk2 causes a pressure difference (diff. pressure) in relation to the ambient pressure. The red fan in the Flowfinder-mk2 is used to regulate this pressure difference. The speed of the fan is a measure of the air flow rate (air volume flow) through the ventilation valve.

With the Ventiflow-mk2, a lot of attention has been paid to the shape of the “conical” housing and the red flow finder in order to achieve the lowest possible air resistance. Studies of different flow models have led to the current shape of the housing and the patented flow straightener, turning the airflow into a calm flow that passes as straight as possible through the anemometer.


The FlowFinder-mk2 is delivered in a solid case and is immediately ready for use for measuring volume flows. Pre-calibration (also called zeroing) is not necessary. The FlowFinder-mk2 is ideally suited for ventilation valves or rosettes often found in homes but also for measurements on ventilation systems in utilities such as offices and hospitals. We have a range of attachments (or hoods) available for this and, if necessary, with a flow straightener to greatly reduce the turbulence of the air in the case of swirl diffusers, thereby reducing the measurement uncertainty.


The starting point for the VentiFlow-mk2 was to measure well without pressure compensation. The shape of the cone and the patented flow straightener ensure low resistance and an air flow that is always the same through the anemometer, regardless of the type of valve. With a range of 10 to 100 m3/hour, this airflow meter is ideally suited for the adjustment of WTW installations and ventilation systems in houses and flats. The short measuring cycle and the super handy app, which is available for most smart phones, make it a very pleasant measuring instrument to use. The case in which the instrument is supplied can be used as a stepping stone for easier access to the measurement points.

Which flow meter to buy?

The VentiFlow-mk2 is very useful in places where there is a lot of repetition and the airflow does not exceed 100 m3/hour. For example, in flats or houses that are always the same. The VentiFlow is above all a light, fast and accurate measuring instrument. With the available app, you don’t really need a pen and paper anymore.  A stepladder is also not necessary because the case serves as a step.

The FlowFinder-mk2 has a large range (10..850 m3/hour) and measures very accurately at low and high flow rates. For ventilation systems with low resistance, the FlowFinder is the instrument of choice.

We see it happen more and more in projects with a lot of repetition that first a number of houses are measured with the FlowFinder-mk2 and with the VentiFlow-mk2. The correct setting of the VentiFlow-mk2 is then determined for each valve so that all other houses can be measured quickly. The report can then refer to the FlowFinder-mk2 that served as a reference.

More information about our flow meters?

Do you have a question about one of our flow meters, or would you like a demonstration or a quotation without obligation? Let us know by leaving your name and number using the form on this page. Of course, you can also just mail to or call +31 (0)70 – 3070703.

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