Laser diffraction spectrometer - We measure drop size distributions quickly and efficiently for you!

The laser diffraction spectrometer - a cost-effective and efficient method for measuring drop sizes and their complete distributions in a spray.

The great advantage of this laser-optical measuring method is that the measurements are always non-invasive and therefore free of influence. The spray properties are therefore not changed during the measurement due to disturbing probes for example. This is of course very important in the interest of reproducibility and measurement accuracy!

We offer measurements with the laser diffraction spectrometer as a service!

Special challenges in measuring drop size distributions:

The spray supplied by nozzles and atomizers is usually very dense. It consists of a large number of individual drops that move at high speed. With a few exceptions, the spray contour is also conical and thus three-dimensional.

Attempts to obtain reliable information about the droplet sizes in a spray and thus about the spray properties by imaging methods usually fail. On the one hand the number of drops in the spray is often very high, on the other hand the drops have a high speed. The consequence of this is that only a milky and blurred fog can be seen on a picture.

This means that reproducible measurements of droplet size distributions in the spray of a nozzle cannot usually be achieved with this method.

Attempts to determine the different drop sizes by probes or by collecting drops also fail. It is also important to bear in mind that any intervention in the spray naturally also causes undesirable interactions. This can significantly change the original spray properties.

The picture shows the spray of a nozzle in the laser beam of the laser diffraction spectrometer. Picture: IBR Zerstäubungstechnik GmbH

The laser diffraction spectrometer - an efficient and flexible measuring technique

Measurements with the laser diffraction spectrometer are an elegant, cost-effective and efficient method to determine the complete droplet size distribution in a spray.

This measuring technique uses the special optical properties of a laser beam. This is traversing the spray generated by a nozzle. Depending on their size, the drops in the spray cause the laser light to diffract.

The use of special lenses results in a specific diffraction pattern which depends on the droplet sizes. A special software evaluates this pattern quickly. The result of such a measurement is a report containing the characteristic droplet diameters information about the entire droplet size distribution.

This is an integral measuring method. Integral in this case means that a certain volume of the spray is measured. This measuring range is formed by the diameter of the laser beam and the illuminated spray area. To measure the complete spray, the position of the nozzle in relation to the laser beam is changed. This makes it possible to reliably measure the edge areas of a spray.

This must be taken into account!

The measurement distance between the laser beam and the nozzle orifice is important. The spray properties at a nozzle change with increasing distance from the nozzle orifice. This is due to evaporation effects on drops and drop coalescence. Drop coalescence is the confluence of drops. Two spray properties can therefore only be meaningfully compared with each other if they were recorded under identical conditions.

If, for example, sprays produced by propellant gas bottles are measured, a special phenomenon occurs. Propellants and solvents lead to a so-called optical density shift. The consequence of this is that the measuring protocol of the laser diffraction spectrometer shows a few, but extremely coarse drops. However, these are not really present! Rather, the optical density shift is responsible for this. Our experts recognize this of course. The software of the laser diffraction spectrometer offers special functions to make the necessary corrections.

Of course, the complete measuring conditions must also be documented; also temperature, humidity and ambient pressure! Of course, our experts for spray measurement technology pay attention to this.

Click on the image to view or download the measurement report as a PDF file.

The result of a measurement with the laser diffraction spectrometer.

After completion of the measurement, a complete and meaningful measurement report is available after a short time.

In addition to the usual characteristic drop diameters such as the mean drop diameter d50 and the Sauter diameter d32, the entire drop size distribution is naturally displayed.

This is the only way to make well-founded statements about the finest or coarsest drops in a spray. This is a very important information for obtaining statements on undesired overspray effects or the addition of drops to walls.

Further interesting information can be found in the measurement protocol of the laser diffraction spectrometer measurement. For example, information on the drop concentration in the measuring volume and the calculated specific surface area of the spray.

Only with this comprehensive information it is possible to carry out reliable calculations on mass and heat transfer processes or on downstream process engineering procedures.

This also clearly proves once again that individual data such as average droplet diameter d50 or Sauter diameter d32 are not sufficient for spray properties!

Measurements with the laser diffraction spectrometer as a service.

Of course, this is also part of the full service of IBR Zerstäubungstechnik GmbH. The measurement of complete droplet size distributions at nozzles and atomizers with the laser diffraction spectrometer is also offered as a separate and independent service. This also applies to nozzles and atomizers already in use.

This also makes sense, since possibilities for process optimization can often only be reliably estimated when the current spray properties are known. Only a reliable as-is analysis allows statements to be made about optimization potential.

In a first step, we check whether the laser diffraction spectrometer is the appropriate measurement method. There are physical limits for this measurement method. If, for example, the spray is extremely dense or there are very large drops, other measuring methods may be considered. Then we recommend alternative measurements with the Phase Doppler Anemometer; PDA.

If desired and technically possible, we can also carry out these laser-optical measurements of drop size spectra in your company on request.

Let us advise you now, which possibilities the laser diffraction spectrometer offers.
Consultation on measurements with the laser diffraction spectrometer.

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+49 251 2 87 99 53 – 0

and let us connect you with specialists for spray measurement technology. Alternatively, you can of course also use our contact form.