Steve Thompson wrote:
>
>>>> http://www.g8wrb.org/data/Eimac/3CX1500A7.pdf
>>> As well as a data sheet with airflow figures, you can also find an
>>> article describing how to estimate what flow/pressure a blower will
>>> produce. In general, CFM ratings are not a useful guide - you need to
>>> know if a blower will produce enough pressure.
>> Umm, beg to differ. What actually provides the heat transfer is the
>> mass flow rate of air (grams per second) and its specific heat.
>> Unfortunately the mass flow rate of a gas is very difficult to measure.
>
>I don't think we differ. What I meant was that blower cfm ratings
>alone are not a useful guide to suitability for a given valve. First
>you have to establish if the blower can produce the pressure - then
>you can see if there's enough volume/mass flow. Blower cfm ratings are
>nearly always into free air, which tells you nothing about the 'load
>line'. I have a lovely snail blower with a fancy cast housing and so
>on. From memory it's rated at close on 300cfm - but feed it through an
>8877 and you're hard pushed to feel any air flow coming out.
>
Sorry, I misread your previous posting as referring to the CFM rating of
the tube, not the blower.
Very much agree about the CFM rating of the blower being of little use.
It is the maximum output with no flow resistance, which is pretty much
irrelevant.
--
73 from Ian GM3SEK
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