Material pickup rate

[Dirn]

I think I'm missing something very simple but I'm stumped.
Here's my problem.
I have a material that weighs 100# pre cubic foot.
I have a conveying velocity of 7000 fpm and a total CFM of 150.
The Cu. Ft. of air per pond of material is roughly 35.
Based off these numbers I'm trying to figure what my flow rate is. It's seems as simple as taking the total cfm and dividing it by the required per pound giving me the rate the material is picked up.... 2.857#/min....
Is this correct or am I missing something?

 

[ione]

35 [Cu. Ft(air)/lb(material)] * 100 lb/Cu.Ft (material) * 150 CFM (material) = 525000 CFM (air)

 

[Dirn]

Dear Ione,

Thanks for your reply. I didn't word my post properly, well left out what I was looking to accomplish. Vacuum application.
I'm looking for the rate the material will be picked up per min lets say. My vacuum can handle 150cfm @ 7000fpm thru a 2" line. My material is 100# per cubic foot. I know the vac can pick up the material, just not the rate it will pick it up.

 

[Dirn]

Would 23.33#/min be more realistic?
35[cu.ft(air)/lb(material)]*100lb/cu.ft(material)/150cfm(total flow rate) ?

 

[ione]

150 CFM (air)/[35 cf(air)/lb(material)* 100 lb/Cu.Ft (material)] = 0.043 CFM (material)

 

[Dirn]

Thanks for the reply again.
.043 cfm (material) seems really low. That means it would take nearly 3 hours to fill a 55 gallon drum.

 

[ione]

If you need approx 35 Cu.Ft of air to handle 1 lb of material, you need 35 Cu.Ft of hair to handle 1/100= 0.01 Cu.Ft of material (being your material density 100 lb/Cu.Ft).

So 1 Cu.Ft of air can handle 0.01/35 =0.000286 Cu.Ft of material.

Being your air flow rate 150 CFM you can handle 0.000286*150=0.043 CFM of material.

 

[ione]

Or if you prefer considering a mass flow rate :

0.043*100 = 4.3 lb/min (material)