Static pressure measurement…
Low-profile fans are a special category, but sometimes they are unavoidable in more confined spaces. For technical reasons, it’s always about compromises compared to more respectable fans of normal thickness, but their weight can vary. If the Arctic P12 Slim and Alphacool SL-15 don’t fit your needs, the Scythe Kaze Flex II 120 Slim may be the closest thing to what you’re looking for.
Static pressure measurement…
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.
- Contents
- Scythe Kaze Flex II 120 Slim in detail
- Overview of manufacturer specifications
- Basis of the methodology, the wind tunnel
- Mounting and vibration measurement
- Initial warm-up and speed recording
- Base 6 equal noise levels…
- ... and sound color (frequency characteristic)
- Static pressure measurement…
- … and airflow
- Everything changes with obstacles
- How we measure power draw and motor power
- Measuring the intensity (and power draw) of lighting
- Results: Speed
- Results: Airlow w/o obstacles
- Results: Airflow through a nylon filter
- Results: Airflow through a plastic filter
- Results: Airflow through a hexagonal grille
- Results: Airflow through a thinner radiator
- Results: Airflow through a thicker radiator
- Results: Static pressure w/o obstacles
- Results: Static pressure through a nylon filter
- Results: Static pressure through a plastic filter
- Results: Static pressure through a hexagonal grille
- Results: Static pressure through a thinner radiator
- Results: Static pressure through a thicker radiator
- Results: Static pressure, efficiency by orientation
- Reality vs. specifications
- Results: Frequency response of sound w/o obstacles
- Results: Frequency response of sound with a dust filter
- Results: Frequency response of sound with a hexagonal grill
- Results: Frequency response of sound with a radiator
- Results: Vibration, in total (3D vector length)
- Results: Vibration, X-axis
- Results: Vibration, Y-axis
- Results: Vibration, Z-axis
- Results: Power draw (and motor power)
- Results: Cooling performance per watt, airflow
- Results: Cooling performance per watt, static pressure
- Airflow per euro
- Static pressure per euro
- Results: Lighting – LED luminance and power draw
- Results: LED to motor power draw ratio
- Evaluation
On the evaluation page, the link to frequency analysis on plastic filters was wrong (39 instead of 29). Also, the summary was wrongly replaced by the spec table.
On your evaluation of frequency, you say thay the weakness of the fan only shows when it runs above 1100 RPM (that is 45 dBA). But from reading the charts, there seems to be strong peaks that appear in 39 dBA mode (959 RPM) as well. Did I interpret the data incorrectly?
Thank you for the heads up. Corrected. Including the charts that were really messed up. I was already in advanced stages of exhaustion when I released it yesterday…
… you read the spectrographs well. Yes, you are right, even the 39 dBA (~959 rpm) mode is characterized by more pronounced tonal peaks, so I’ve modified that statement a bit. Below 850 rpm it’s fine in that respect. Approximately such speeds at 39 dBA correspond to tests with a plastic filter and on a grille, which increase the noise level, so when tuned to the same level the fan speeds will always be a bit slower than in a use case without an obstacle.
So thanks for this observation and apologies for the inaccurate interpretation of the results. I wrote the article a bit under pressure and at the same time on the verge of complete exhaustion. I hope that similar mistakes will be avoided in the future.
You don’t have to apologize, it does not take away from the fact that the overall analysis is great work.
Health is very important. I hope you’ll find time to take a good rest and don’t push yourself too hard 🙂. Take care.
Guys, please test 120 and 140x25mm Kaze Flex – they were highly praised by other (but not as advanced as you) reviewiers, especially as case fans. I generally really like them from my own experience for being solid performers; sounding well; having quiet motor and bearing and representing nice quality additionally proven by few years of using them in my own pc.
Sure, the 120 and 140 mm Kaze Flex II will be next in line as far as Scythe fans are concerned. I mean, maybe the Grand Tornado model, which is close to release, will fit in between them.