I agree the gallons per minute rating for air compressors seems odd, but when one looks at adverts in the USA for compressors with storage tanks, the tanks themselves are sizes in gallons (30 Gal, 50 Gal. etc..). If the compressor flow is sized in gallons per minute, then the customer gets some idea of the rate of replenishment of the storage tank.
This of course is all completely confounded by the fact that air is compressible and contains moisture - and a gallon (or cubic foot, cubic meter, etc..) at one pressure/temperature/moisture combination isn't the same mass as when at a different combination. Hence the introduction of the terms ACFM and SCFM (Actual and Standard Cubic Feet Per Minute) where the mass flow rates are represented at a specific set of conditions. It is a bit confusing, no matter what system of units you use (though I do find calculations in SI much simpler than US Customary). This link is a good one. http://www.cleandryair.com/scfm_vs__icfm_vs__acfm.htm Regards, Andrew Veit Systems Design Engineer MTS Systems Corp Ph: 919.677.2507 Fax: 919.677.2480 1001 Sheldon Drive Cary, NC 27513 -----Original Message----- From: Robert Wilson [mailto:robert_wil...@tirsys.com] Sent: Friday, June 21, 2002 12:27 PM To: richwo...@tycoint.com; emc-p...@majordomo.ieee.org Subject: RE: SI Unit for volume Only if it applies to fluid volume. If it applies to volume of a solid, then it is traditional to use cubic centimeters, or even m^3. The latter is a heck of a big volume, and sounds almost silly, but it is increasingly used. For example, in the latest Ferroxcube ferrite core catalogue, specific values of core hysteresis losses are given in KW per m^3 of ferrite material, even though these are the same units as W/cc. Liters are never mentioned or ever used in this context. Context seems to be important, so the units used should make sense when considering what the units apply to. A non-metric example of something that makes no sense is how American companies are now rating air compressors in "gallons per minute". This is really absurd since all tools that are powered by compressed air sold in the US are rated in CFM, the gallons/minute rating is useless. Bob Wilson TIR Systems Ltd. Vancouver. -----Original Message----- From: richwo...@tycoint.com [mailto:richwo...@tycoint.com] Sent: June 21, 2002 5:28 AM To: emc-p...@majordomo.ieee.org Subject: SI Unit for volume When stating a cubic volume in SI units, is liters the correct unit. If not, what is the correct method of expression? Richard Woods Sensormatic Electronics Tyco International ------------------------------------------- This message is from the IEEE EMC Society Product Safety Technical Committee emc-pstc discussion list. Visit our web site at: http://www.ewh.ieee.org/soc/emcs/pstc/ To cancel your subscription, send mail to: majord...@ieee.org with the single line: unsubscribe emc-pstc For help, send mail to the list administrators: Ron Pickard: emc-p...@hypercom.com Dave Heald: davehe...@attbi.com For policy questions, send mail to: Richard Nute: ri...@ieee.org Jim Bacher: j.bac...@ieee.org All emc-pstc postings are archived and searchable on the web at: http://ieeepstc.mindcruiser.com/ Click on "browse" and then "emc-pstc mailing list" ------------------------------------------- This message is from the IEEE EMC Society Product Safety Technical Committee emc-pstc discussion list. Visit our web site at: http://www.ewh.ieee.org/soc/emcs/pstc/ To cancel your subscription, send mail to: majord...@ieee.org with the single line: unsubscribe emc-pstc For help, send mail to the list administrators: Ron Pickard: emc-p...@hypercom.com Dave Heald: davehe...@attbi.com For policy questions, send mail to: Richard Nute: ri...@ieee.org Jim Bacher: j.bac...@ieee.org All emc-pstc postings are archived and searchable on the web at: http://ieeepstc.mindcruiser.com/ Click on "browse" and then "emc-pstc mailing list" ------------------------------------------- This message is from the IEEE EMC Society Product Safety Technical Committee emc-pstc discussion list. Visit our web site at: http://www.ewh.ieee.org/soc/emcs/pstc/ To cancel your subscription, send mail to: majord...@ieee.org with the single line: unsubscribe emc-pstc For help, send mail to the list administrators: Ron Pickard: emc-p...@hypercom.com Dave Heald: davehe...@attbi.com For policy questions, send mail to: Richard Nute: ri...@ieee.org Jim Bacher: j.bac...@ieee.org All emc-pstc postings are archived and searchable on the web at: http://ieeepstc.mindcruiser.com/ Click on "browse" and then "emc-pstc mailing list"
