On Oct 21 , at 7:41 AM, John M. Steele wrote:
> I'm not really out to hype this fan company. However, it is a nice example
> of US companies able to adapt and provide metric products for export markets.
> It would be interesting to know whether the US product line is really metric
> or Customary.
> http://www.pr.com/press-release/362583
> Invisco, the leading supplier of whole house fans for the US, is introducing
> the most powerful 760 mm fan yet offered for Australia and New Zealand. At
> 13,600 cubic meters per hour (CMH) this fan moves more air with a smaller
> hole in the ceiling than any other yet available.
>
> (Yes, they could use a lesson in proper use of SI symbols, m³/h, but at least
> they are trying and exporting.)
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The above article posted by John Steele was interesting and encouraging.
I wrote an email to the company commending them on using metric and suggested
further improvements.
In case you are interested, here is what I wrote:
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It is refreshing and welcome to see product capabilities in solid metric rather
than Ye Olde English units, as in your web article:
"Invisco Whole House Fan Company Announces 760 mm (30 inch) 13,600 CMH
(8000 CFM) Product for Australia and New Zealand"
May I suggest a further improvement. Rather than developing your own
abbreviations or acronyms for air handling capacity, such as CMH, why not adopt
the officially standardized symbols of the SI metric system. In SI metric, the
symbol for metre is "m" (not "M") and for the cubic metre is "m3" (not "CM").
(I need to note that the "3" in "m3" should be a superscript which I cannot
reproduce here.)
Although the hour is not an SI metric unit, it is acceptable for use with SI
units and has the prescribed symbol; "h" (not "H"). Also, the word "per" in SI
is always symbolized by the slash "/" so that cubic metres per hour, in its
complete form would be repesented by "m3/h" (with the "3" as a superscript or
exponent as noted above).
Your use of "CFM" for "cubic feet per minute" cannot really be faulted because
Ye Olde English system of units does not have any officially prescribed symols
for its units, leaving the way open for anyone and everyone to invent as many
different forms as they might wish.
However, to make "CFM" relate better to the SI units (m3/h), one could use
"ft3/min" where the use of "ft" for feet is common in the US and "min" for
minutes happens to be the SI standard symbol for minutes. Also, the slash for
"per" is again the SI way of writing it.
I hope my suggestions are of interest to you.
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Bill Hooper
1810 mm tall
Fernandina Beach, Florida, USA
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SImplification Begins With SI.
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