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## [AMPS] Blowers

 To: [AMPS] Blowers davek@medphys.ucl.ac.uk (Dave Kirkby) Tue, 10 Mar 1998 13:52:13 +0000
 ```W7CW Jay E Ostrem wrote: > Has anyone experimented with using a furnace blower for cooling their > tubes? I was curious if anyone had actually measured available back > pressure for any particular size wheels. The handbooks list ratings > for > different size Dayton blowers, and wondered if the furnace type would > be > worth pursuing for cooling some of the larger triodes. > 73 Jay W7CW > > 1AB Ranch > Gillette, Wyoming > I've spent some considerable time playing with centrifugal blowers of various sizes to cool big tubes, and looking at the theory to some extent - without wishing to do a PhD in the subject. I don't know what blowers are used in furnaces, but if they are centrifugal, the following might be of use. The cut off back depends mainly on the speed and diameter, as: Cutoff back pressure = BPco= 9.5 x 10^ -9 N^2 d^2 where cuttoff back pressure is in inches of water, N is the speed in revs/min and d is the diameter in inches. The free air flow rate (cfm) is roughly: Ffa=3.11 x 10^-4 N w d^3, where w is the wheel width in inches. Once you know the BPco and Ffa, and some data on the tube, you can estimate the flow the blower will produce through your tube. See "Predicting the Performance of Centrifugal Fans for Valve Cooling", D. R. Kirkby, (G8WRB), QEX, October 1997, pages 27-31. I can send you a copy if you wish. I would add that I got so frustrated trying to find a suitable used blower for a 3CX5000A7, that I spent #400 on a new one. -- FAQ on WWW: http://www.contesting.com/ampfaq.html Submissions: amps@contesting.com Administrative requests: amps-REQUEST@contesting.com Problems: owner-amps@contesting.com Search: http://www.contesting.com/km9p/search.htm ```
 Current Thread [AMPS] Blowers, W7CW Jay E Ostrem [AMPS] Blowers, Dave Kirkby <= [AMPS] Blowers for finned tubes, John Lyles [AMPS] Blowers, km1h @ juno.com [AMPS] Blowers, W7CW Jay E Ostrem [AMPS] Blowers, Ian White, G3SEK [AMPS] Blowers - > Protection from failure, Dave Kirkby [AMPS] Blowers, Walter Dail [AMPS] Blowers, John Brosnahan [AMPS] Blowers, W/Z Kornienko [AMPS] Blowers, Frank & Barb Ayers [AMPS] Blowers, Paul Hrivnak