Blower question - What do these numbers mean?

[wendybritt]

When looking at the specs for various shaded pole blowers at Grainger there are lists of numbers like this and I am frankly stumped as to what they mean.

CFM @ 0.000-In. SP 1005
CFM @ 0.125-In. SP 968
CFM @ 0.250-In. SP 930
CFM @ 0.500-In. SP 850
CFM @ 0.750-In. SP 773
CFM @ 1.250-In. SP 480

Can someone give me some clue as to how to decipher them? I need about 800 CFM and can use whatever size duct is required. DH will help install it (through the wall), but also doesn't understand the specifications. I have banged my head against this several times, and now I need help.

I traded with my boss for a great hood - 36" wide, 24" deep, 18" high with halogen lights inside. It has no blower (which was just fine). It's a Five Star Hood and has been sitting in the box at work (custom cabinet shop) for several years. (I found a Five Star remote blower that I can order for nearly $700 - but I think that's crazy!) We need to get the wiring in the shed done soon....and I'd like to have the vent all figured out before we complete the electrical. Can someone smarter than me help me out?

[bhhco]

Those are static pressure (SP) adjustments. Static pressure is a confusing sounding term for resistance to flow. For example, if you put a 90 elbow turn in the duct, that causes a resistance to flow.

CFM @ 0.000-In. SP 1005 means: 0.000 static pressure, i.e., if there is nothing creating any resistance to the flow... then the fan can pull 1005 cubic foot of air through the pipe, per minute.

CFM @ 1.250-In. SP 480 means 1.250 static pressure (measured in inches -In.), ie., if there is that much resistance to the flow... the fan can pull only 480 cubic foot of air through the duct, per minute.

You would have to do a static pressure calculation based on duct size, material, turns radius and locations, reductions, and duct length -- and the result would be a The SP#... then look for the number on that table and it will tell you what to expect that fan to be able to pull through it, in CFM.

Mike and Dale have that all written out somewhere... how to do the calcs and what to use... I'm not sure where though.

Me

[MikeAurelius]

http://www.artglassforum.com/forums/...ead.php?t=2293

http://www.artglassforum.com/forums/...ead.php?t=2294