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I can't think of any merit to this... However, there are people, who will remain annonymous... that would disagree. What they are doing is testing by the method described above, and then using this information to determine the flowrate in a package for a given static pressure. Or as they put...

ko99, I completely agree with what it is your saying. I don't believe that I was very clear with what I'm asking. what I'm trying to figure out is if there is any merit to measuring a "fan curve" (just like one would do, to dertermine the fan performance) except by placing the fan in the...

I know how to measure a fan curve over a finite pressure range. I also, know how to measure the system response of the package that the fan will go in. As we all know, the theoretical operating point of the system would be intersection of the fan curve and the system curve. However...

Thank you! So simple, yet I somehow managed to glaze over that.

I am trying to put a square box around a dimension on my solidworks drawing to represent a theoretically exact dimension for geometric tolerancing purposes. Thus far, all I've been able to do is get a round bubble around the dimension, representing an inpection dimension. If there any way to...

Tunalover, I would be very interested in this data. I have no problems geometric dimensioning and tolerancing. As a matter of fact, I wish that more companies would adopt this as a sole method of dimensioning their drawings. It just solves to many problems (assuming that a supplier can...

ko99, thanks for your reply. I do realize that fan curves are published values over a range of pressures. That was just bad communication on my part. In such situations that I do have obstructions near the front of the fan, I do indeed test the fan in that situation. since the measured point...

Theoretically speaking a DC fan should be operating at some point on its predetermined fan curve. I was always told that a rule of thumb is to not obstruct the fan's flow half the distance of the fan's diameter. This way, the measured fan curve may still be observed in an enclosure. However...

Is there anyone here that knows what kind of tolerances can be held on a PCB in production from the edge to the center of a hole on and from edge to edge of a board as well. I'm looking for the best case tolerance without adding significant cost.

Can anyone here provide a link detailing the proper test method of determining a fan performance curve on a flow bench device? I know it can be done, however I'm not sure at to the procedure and any other standards that are relative to the test.

Can anyone point me in the right direction of some good online references for fatigue prediction of electronic components under random vibrational loads? I know where to look if I am to shell out a little bit of money. However, I was looking to see if I can get away without doing so.

I was quoted at about $8.00 per square foot (in bulk quantities) for 20 mil isodamp material with PSA. They also offer Confor foam at about 1.35mm thick. That stuff if pretty amazing how well it absorbs shock.

No, I'm not a fan manufacturer. The L10 data was provided to me by the fan manufacturer. I did talk to the rep. while they were here about it and they did not know at the time. The fan has two ball type bearings. Its a dc brushless axial flow fan (40x40x28mm).

Just though that I would add that this is after approx. 1400 hours of total fan testing

While observing L10 life expectancy fan test data, I notice that there is approximately a 5% increase in the rotational speed of the unit from the time the test start and ends. This is for a ball bearing unit with a max flowrate of 23 CFM and runs at about 13,000 rpm @12v. It would seem to me...