[Amps] Alpha 91b fan/blower motor

Bill Turner dezrat at copper.net
Wed May 24 12:27:27 EDT 2006


At 06:47 PM 5/23/2006, KR4DA wrote:

>I recieved the fan today.
>BUT the SPECS on the label say  RPM 1100 and HP 1/500
>The web page says RPM 3000 and HP 1/200

*********** REPLY SEPARATOR ***********

RPMs are only part of the issue. The geometry of the fan is also 
important, especially the angle of the blades as they cut through the 
air. Low RPMs should have a high blade angle and vice versa.

The best way to ensure correct cooling is to measure the tube 
temperature directly when running under full load. Use either a 
non-contact thermometer (my choice) or color-changing paint or 
crayon. Compare the reading with the tube manufacturer's specs and 
you'll have your answer without worrying about RPM, pressure 
difference, etc, etc. Tube temperature is the only thing that 
matters. All those other measurements are just a way of getting you there.

Harbor Freight has a great non-contact thermometer for $39.95 + shipping.


You can download the product manual from that site too. I got one and 
it works great. I have found uses for it I never dreamed of when I 
ordered it, such as measuring the temperature of my aquarium, 
checking the refrigerator and freezer for proper operation, and a 
dozen others. Sure, you could do those with a regular thermometer, 
but this is so fast and easy it's all I use now.

The usual disclaimers apply; just a satisfied customer.

Bill, W6WRT

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