What kind of Fan for Vacuum Application ?

[Adrian2]

Dear Folks;

I need to specify a fan for a material handling machine in which a 4'x8'x3/4" sheet of plywood is slid under a vacuum plenum chamber and hopefully held there by the vacuum created by a centrifugal fan. I am limited by my maximum 30 HP fan drive motor running at 1750 RPM. The plywood weight should be a maximum of 200 lbs. Being a flat sheet, there is a relatively large surface area over which a vacuum may be applied.

I have so far been told that most centrifugal fans for blower applications max out at 7-8" water pressure. I am not sure if this would be sufficient to support a vacuum strong enough to support a sheet of plywood of this weight.

Based on this rather sketchy information does anyone have any fan type, size, vendor reccomendations ?

Any help would be much appreciated

Regards Adrian

 

[quark]

Adrian2!

Can you work in these lines?

The total area of the sheet is 32 sq/ft = 4608 sq.in. The weight of the plank is 200lbs. So the required pressure to hold it is 200lbs/4608sq.in = 0.0434 psi.(differential)

1 psi = 26.78 inches of water column roughly.

So 0.0434psi corresponds to 1.16" of wc. So this should be the differential pressure on the plank.

Note: I never worked it practically.

Regards,



Repetition is the foundation of technology

 

[Adrian2]

Thank you quark;

That information is very useful. I know I cannot use the entire surface area of the sheet but working backwards using your formulas I see that if I had a fan capable of 6" wc, which I know I can get, I would have to design a plenum that would have open area to the sheet of 893 sq. in. approx.

My actual fan would have to be more powerful than the required 6" wc but I think there is a possiblity that I will not need to resort to a special purpose built fan here

Again many thanks

Adrian