| Re: [GMCnet] Electric powered altitude compensation blower [message #175979] |
Sun, 08 July 2012 00:05  |
Steve Jess
Messages: 169
Registered: April 2012
Karma: 0
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Senior Member |
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Something occurred to me while lurking over this conversation.
The ratings on these blowers (e.g. CFM) assume sea-level air pressure, don't they? Shouldn't the output, and the efficiency of the blowers be down-rated when calculating their effect at 10,000 feet?
In other words, a 1200 CFM blower at sea level would be putting out the equivalent of 800 CFM (sea level) at 10,000 feet.
Steve Jess - Boise, ID
1977 GMC Palm Beach "The DreamLiner"The 10,000 pound antique Home Theater with plumbing
> Robert Mueller wrote on Sat, 07 July 2012 16:16
> > Mark,
> >
> > Send us a link to the blower you speak of below.
>
>
> No worries, mate (I spent 2 years in NSW)....
>
> http://www.grainger.com/Grainger/DAYTON-PSC-Blower-12G810?Pid=search
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| Re: [GMCnet] Electric powered altitude compensation blower [message #176081 is a reply to message #175979] |
Sun, 08 July 2012 18:23  |
habbyguy
Messages: 896
Registered: May 2012
Location: Mesa, AZ
Karma: 3
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Senior Member |
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| Steve Jess wrote on Sat, 07 July 2012 22:05 |
Something occurred to me while lurking over this conversation.
The ratings on these blowers (e.g. CFM) assume sea-level air pressure, don't they? Shouldn't the output, and the efficiency of the blowers be down-rated when calculating their effect at 10,000 feet?
In other words, a 1200 CFM blower at sea level would be putting out the equivalent of 800 CFM (sea level) at 10,000 feet.
Steve Jess - Boise, ID
1977 GMC Palm Beach "The DreamLiner"The 10,000 pound antique Home Theater with plumbing
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The blower will produce less overall output, because it has less overall input (thinner air), but will produce more pressure differential input-to-output because the input absolute pressure is so much lower. Think about trying to compress cooked spaghetti (sea level air) and fiberglass insulation (high altitude air). While you'll be getting less mass with the fiberglass, you'll end up with more fiberglass "packing" than spaghetti for a given amount of work.
And that's about the least appetizing example I can think of...
And FWIW, I actually had a reference for that 1.5x multiplier at 10,000 feet, but for the life of me, can't find it right now...
Mark Hickey
Mesa, AZ
1978 Royale Center Kitchen
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