John Gillis wrote:
>
> Hello to one and all. In the Lab. where I work we are in the process of
> up-grading much of our equipment. One of the items being removed is an
> Atlas Copco compressor. I know this is a top make and the machine has had
> very little use since it was installed in 1973, what I can't figure out is
> how to gauge its output. I would normally look for the c.f.m rating, i.e
> cubic feet per metre, which would need to be around 7 to be of any use to
> your run of the mill home restorer. On this machine however I can find only
> a rating in kp/cm2 and lb/in2, the former being a max of 10 and the latter
> 140. The second is obviously pounds per inch but what is the first and how
> do both equate to c.f.m ???. Is this machine worth having????, It does have
> a good sized tank at 150lt, all advice welcome.
>
> John Gillis
> 1954 TR2 TS3618. October 1954 (ground up)
> 1964 Triumph 3TA 350cc (a little gem)
> Trinity College
> Dublin,
> IRELAND.
cfm = cubic feet/MINUTE, not metre. A good rule of thumb is that a
compressore will produce 4 to 5 cfm/horsepower, so you should look at
the motor to determine it's horsepower. This will be listed on the
maker's plate. However, the motor may be rated in kilowatts (kW). The
conversion is .746kW = 1 HP. Therefore, if the motor is rated in kW the
cfm is in the 3 -3.5 cfm/kW range, and if in HP the cfm is 4-5 cfm/HP.
Thus a 5 HP compressor is around 20-25 cfm. A 10 kW compressor would be
30-35 cfm. These are approximations only!
BTW, kp/cm2 is kilopond/square centimetre, which is simply a metric unit
of pressure. The conversion is 1 kp/cm2 = 14.22 psi, approximately.
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