Our database now includes one hundred fans—75 in the 120 mm format and 25 models with a physical size of 140 mm. In this article, we have compiled all data into unified charts. What was once separated for clarity is now brought together again, and the commentary will also include a… look ahead regarding fan testing. But we can already reveal that there is still a lot more to come.
Measurement of static pressure…
Finally, it is time to move further down the tunnel a bit. Just behind the fan is a static pressure sensing probe. Its position has been chosen with maximum measurement efficiency in mind. In other words, the sensors are placed at the points of highest pressure (although this is virtually the same everywhere in the unconstrained part of the tunnel).
The Fieldpiece ASP2, which is connected to the Fieldpiece SDMN5 manometer, is used to measure the static pressure in the tunnel. The latter also allows measurements in millimetres of water column, but we measure in millibars. This is a more finely resolved base unit for this meter. And only from there we convert the measured values into mm H2O to allow easy comparison with what the manufacturers state.
While we wrote when measuring noise levels that our results could not be compared with the parameters, that is no longer the case here. As long as the fan manufacturers do not embellish the parameters, they should quote approximately the same pressure values as our tests show. The most significant deviations can only arise at the level of varying accuracy of the measuring instruments, but these are negligible percentages.
The greater the difference between the manufacturer’s claimed values and ours, the less the specifications correspond to reality. If the claimed values are significantly higher, it is certainly an intention to artificially give an advantage to the fans on the market. However, if the manufacturer quotes a lower pressure value than we do, it points to something else. Namely, a weaker tightness of the measuring environment. The less tight the tunnel is, the lower the pressure you naturally measure. This is one of the things we tuned for an extremely long time, but in the end we ironed out all the weak spots. Whether it’s the passage for the probe itself, the flanges around the anemometer, even the anemometer frame itself, which is made up of two parts, needed to be sealed in the middle. Finally, the flap at the tunnel outlet must also be perfectly tight. That’s because static pressure has to be measured in zero airflow.
But there is one thing that often lowers the pressure of the fans a bit. And that’s protruding anti-vibration pads in the corners or otherwise protruding corners. In other words, when the fan doesn’t fit perfectly to the mounting frame at the inlet, and there are small gaps around the perimeter, that also affects what you measure. But we have not gone into this because it is already a quality feature of the fan. In the same way, it will “stand out” and perform a bit weaker than it has the potential to do with better workmanship, even after application by the end user.
Thank you for all the hard work in reviewing and compiling this information!
If it’s not too much effort, would it be possible to maintain a page like this going forward with each new reviewed fan added on? It’ll make a convenient location to be able to reference back to (a one-stop-shop if you would).
Thank you for the comment! 🙂
What exactly do you mean by keeping it the same as in this article?
We separated the 140 mm fans from the 120 mm ones to prevent the charts from becoming too long. Even as they are now—especially in the 120 mm category, where we have more models—the graphs already take up quite a lot of vertical pixels. If combined, navigating them would be rather inconvenient, even on high-resolution monitors
Great job, guys.
Thank you! 🙂