[Amps] Muffin Fans and hot exhaust

[Ron]

In working with fans , pressures developed are less than 1 inch of water
where 1 atmosphere is roughly 32 feet of water or about 14 lbs / sq. in.
If it develops more than say 1/2 in of water , it is a blower.
All my experiments show that it works better blowing than sucking for
the reasons mentioned by Dave.  If there is no choice ,as in a high
efficiency furnace with a blower placed on the exaust plenum,  you got
to do what you got to do.
---
Ron


"Dr. David Kirkby" wrote:
> 
> Bill Smith wrote:
> 
> > Do the muffin fans hold up ok with all the hot air
> > being pulled through them?  I use one to enhance the
> > exhaust from two 3-400Z tubes.
> > 73,
> > Bill
> >
> 
> As someone else has said, fans work better when pushing air, rather than
> pulling it. Assuming a local air pressure of 760 mm of mercury, the
> greatest pressure drop a fan can possibly produce when sucking is 760 mm
> of Hg - the negative vacuum does not exist to my knowledge. In contrast,
> when pushing air, there is no theoretical limit - ignoring the possibly
> of liquefying the air.
> 
> The above argument does not prove fans work better at more typical
> pressures, but I believe this is the case.
> 
> Like any component, fans last longer when cool.
> --
> Dr. David Kirkby,
> Senior Research Fellow,
> Department of Medical Physics,
> University College London,
> 11-20 Capper St, London, WC1E 6JA.
> Tel: 020 7767 6409 Fax: 020 7769 6269
> e-mail davek@medphys.ucl.ac.uk
> 
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