cfm calc

[Greg Hermann]

>Thanks for the detail greg.. wouldnt want someone to think the whole picture
>was there..
>
>Thanks for explaining and not just saying :"you did" and leaving it there..
>
>We commonly have to calculate the max CFM given a VP of somewhere below
>10"Wc, never we do a theoretical MAX max.  thx again.

It's pretty safe and reasonably accurate to treat the flow of a
compressible gas--like air--through an orifice  as flow of an
incompressible fluid--up to a pressure ratio of about 1.1 : 1 . (That's
absolute pressure ratio) Beyond that, it's best to check what is happening
in more detail.

Hope I didn't muddy the picture too much---

Greg
>
>> >hope I didnt mess that up -
>>
>> You did.
>>
>> At an absolute pressure ratio across an orifice in the neighborhood of
>2:1,
>..
>..
><snip>