RE: maximum duct velocity

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

> -----Original Message-----
> From: Neil Stone [SMTP:jnstone@MNSi.net]
> Sent: Tuesday, May 15, 2001 11:09 PM
> To: PipingDesign@yahoogroups.com
> Subject: Re: [PipingDesign] maximum duct velocity
>
> The maximum velocity you can take in a duct is when the duct pressure loss
> just equals the fan head - this can be as high as you like, up to sonic
> velocity. In practice, most main ducts have velocities in the range 40-75
> ft/sec. As the duct diameter increases, the velocity can be increased
> because the wall area decreases as a ratio to the cross section (less
> friction),
> BUT, in certain parts of a system, the velocity may be as low as 15
> ft/sec,
> or as high as 150 ft/sec. Other factors that affect the 'maximum'
> velocity
> are the type of gas and its density.
> Neil
>
> At 04:47 PM 5/15/2001 +0530, you wrote:
> >I have little problem in Duct velocity. For a given I.D. fan what will be
> >the maximum velocity we can take in Duct. What is the limiting factor of
> >duct velocity according to fan design.
> >Regards
> >Hitesh
>
>
>
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Received on Tue May 15 23:10:00 2001