Maximum Transport Velocity

Posted in: , on 16. Jun. 2011 - 13:51

we have Sigma Mixer , materials are calcite , Sodium ash , Sodium salphate. poring mouh is 18 " , we design canopy hood , it's Projection area 2ft X 4ft , height to mouth 32"

I can calculate Air flow rate using Q=v.h(10x^2 +A)

where A -Projection Area (2ft X 4ft)

X - Distance (32 in)

Vh- Capture Velocity -500fpm

flow rate is 40 800 CFM , I cannot Beleiveble this result

Any body can support to me

Thanks

Uditha ■

uditha
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Maximum Capture Velocity.

Erstellt am 28. Jun. 2011 - 01:56

The calculation you are using is for a vertical face hood (horizontal airflow) which is more appropriate for loading a mixer. A canopy hood will demand a smaller airflow but will interfere with loading of powder.

The capture velocity (not transport velocity) in your case 500 fpm, is an arbitrary number, selected by experience and depending on local conditions. For example, 200 fpm might be O.K if there are no cross-drafts from open doorways, cooling fans etc. That would give you a flow of 15,600 cfm.

In your case, you should use a side-draft hood with side curtains. If you have access to American Conference of Governmental Industrial Hygienists manual, Figure VS-99-05 shows how it looks.

Michael Reid. ■

Re: Maximum Transport Velocity

Erstellt am 29. Jun. 2011 - 08:05

Thanks michel , do you know any recommended books for design of dust extraction system ■

uditha