[TheForge] air compressors, CFM, and psig

[terry l. ridder]

hello;


On Wed, 6 May 2009, Craig Schaefer wrote:

> This all reminds me of going to work at my actual job.   All of this is a
> remarkable treatise on the theory of work and how to accomplish it, but
> there just isn't a damn thing actually getting done.
>

there is something actually getting done, it is helping with the research
into which air compressor i am going to purchase and use in the new
shop.  if i am going to spend $5,000.00+ usd on an air compressor i
would like it to be the correct decision. understand the meaning of the
'cfm' specification is part of making a correct decision.

SCFM (Standard Cubic Feet per Minute)
http://en.wikipedia.org/wiki/SCFM
<begin quote>
CFM

CFM is an often confusing term because it has no single definition that
applies to all instances. In the most basic sense, CFM means cubic feet
per minute. Unfortunately, air is a compressible gas. To further confuse
the issue, a centrifugal fan is a constant CFM device or a constant
volume device. This means that, provided the fan speed remains constant,
a centrifugal fan will pump a constant volume of air. This is not the
same as pumping a constant mass of air. Again, the fan will pump the
same volume, though not mass, at any other air density. This means that
the air velocity in a system is the same even though mass flow rate
through the fan is not.
<end   quote>

this makes me think that the manufactuerers of air compressors are no
better than a used car salesman.

>
> CraigS
> Gresham, OR

-- 
terry l. ridder ><>