An accurate way to measure airflow is to use a peak airflow meter. See
picture here:
http://en.wikipedia.org/wiki/File:Peak_flow_meter_vert.jpg
This is a low-cost device used by persons with asthma to self-monitor
their disease. Widely available worldwide.
73 de
Angel Vilaseca HB9SLV
Ian White GM3SEK a écrit :
> Roger (sub1) wrote:
>
>
>> One other point, I've seen the question raised about how much pressure
>> was a fan generating. For a given tube and existing system you can
>> treat air flow and pressure the same as voltage and current. IF you are
>> getting the required air flow you MUST have the required air pressure.
>> Insufficient pressure and you will have insufficient flow. Get the
>> proper flow and you will have the proper pressure.
>>
>> IF the radiator is plugged or partially clogged you will have high
>> pressure and low flow. But again, it the flow if proper then so is the
>> pressure.
>>
>>
>
> Air flow rate is what really matters in cooling, and all data sheets for
> air-cooled tubes will state the minimum volume flow rate required.
> Pressure drop is only an indirect way of measuring the volume flow
> rate... and actually a very poor way.
>
> Pressure drop measurements in real amplifiers are very prone to errors,
> because the reading will depend critically on the orientation of the
> manometer pickup tubes relative to the air flow. We have no idea what
> the tube manufacturers did to minimize those errors... or even if they
> were aware of them. Because of all these problems, pressure drop is
> probably the wrong thing for us amateurs to measure.
>
> It's actually MUCH easier to measure the volume flow rate directly. No
> elaborate equipment is needed - simply time how long it takes for the
> outlet air to fully inflate a large, lightweight plastic bag. With a
> little care you can measure the volume flow rate within about 10%, which
> is far more accurate than a pressure measurement.
>
> The original idea came from George Daughters K6GT, and details are right
> here in the AMPS archives:
> <http://lists.contesting.com/archives//html/Amps/1998-03/msg00172.html>
>
>
>
>
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