RE: maximum duct velocity

From: <Emmanuel>
Date: Wed May 16 2001 - 16:07:00 EDT

I second this..
Manny
--- Neil Stone <jnstone@MNSi.net> wrote:
> Your fan will develop a specific pressure at 20000
> cfm - let's say 3" w.c.
> (to talk about 'a 20,000 cfm fan' is meaningless if
> you don't say what
> pressure the fan is developing - several different
> fans could draw 20,000
> cfm, all running at different speeds and pressures).
> Now, the smallest duct you can use is a duct system
> that has a pressure
> loss of 3" w.c. This depends on duct diameter,
> length of duct, number of
> bends, tees, branches, density of the gas.
> For preliminary sizing, the most economical duct
> velocity usually turns out
> to be about 50 ft/sec. If you design for a high
> velocity, be careful - a
> small change in duct configuration, or dirt buildup
> in the duct can cause a
> huge increase in pressure loss.
>
> Neil
>
>
>
>
>
>
> At 08:40 AM 5/16/2001 +0530, you wrote:
> >Hi Neil
> >Here I have presented my problem in different way.
> Suppose I have a fan of
> >20000 CFM air capacity.
> >This fan will not suck 20000 cfm air through 12
> inch duct because it has
> >limitation on fan suction velocity according to its
> impeller tip speed. So
> >for a given fan say 20000cfm what should be the
> minimum duct diameter to
> >suck 20000 cfm air. How do we calculate the minimum
> dia of duct requires so
> >that it will convey/pass 100% flow of fan.
> >
> >Thanks all of you for giving your valuable time to
> my problem.
> >Regards
> >Hitesh
> >
>
>
>

---

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Yahoo! Auctions - buy the things you want at great prices <a href="http://auctions.yahoo.com/">http://auctions.yahoo.com/</a> Received on Wed May 16 16:07:00 2001