Spray Booth Input Volume
Spray Booth Input Volume
(OP)
How can a measured duct volume flow rate be only 40% of that measured across the face of the input filter?
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Spray Booth Input Volume
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RE: Spray Booth Input Volume
It would also depend on how flow was measured.
RE: Spray Booth Input Volume
RE: Spray Booth Input Volume
B.E.
RE: Spray Booth Input Volume
RE: Spray Booth Input Volume
RE: Spray Booth Input Volume
Is it possible that some air in the booth is being entrained with the supply air? That would not account for a doubling of the flow however.
What kinds of flows and velocities are we talking about?
RE: Spray Booth Input Volume
The average input duct velocity was 6.94 m/s across the 650 mm diameter giving a flow rate of 2.304 m3/s. The average face velocity of 0.37 m/s was recorded across the filter with an area of 9.165 m2, giving a flow rate of 3.391 m3/s. The fan feeds air into a plennum chamber that distributes the flow across the inside face of the filter with laminar flow.
I'm sure I must be missing some fundamental airflow dynamic principles beyond my understanding as I can't understand how the one fan can appear to be drawing air in a one rate and pushing it out at another!
I am tempted to go back and re-record the duct velocities with a pitot instead of a hotwire just to ensure the accuracy of the results. Hotwires are after all only accurate if positioned correctly. Maybe that's all it is.
On the extract side, the average face velocity across the face of the extract filter was 0.66 m/s , the filter area is 4.449 m2, giving a flow rate of 2.914 m3/s. The duct readings were 6.77 m/s across the 0.332 m/2 duct area giving 2.246 m3/s flow rate.
I would suggest although the recorded values is slightly lower, the extract is roughly the same as the input (as measured in the duct). We know the fans are of a similar size and only the extract damper is adjustable. The test was conducted with this fully open and I understand the seperate design/spec issues with this.
RE: Spray Booth Input Volume
Watch out for the fact that the higher water gauge pressure of the duct can give you a high reading if the static is not right behind the Pitot, but outside in the room.
B.E.