Down Draft Bench Face Velocity
Down Draft Bench Face Velocity
(OP)
Several friendly competitors and I have been arguing over the correct methodology for measuring face velocity at the work surface on a down draft workbench. They claim that the true face velocity is calculated by dividing the air volume by the total area of the workbench surface. For example, if the workbench surface dimensions are 2' x 3' and the air volume is 1000 cfm, then the face velocity is 1000cfm/(2x3) = 166.67 fpm.
I contend that the true face velocity is calculated by by dividing the air volume by the total open slot area on the workbench surface. For example, if the workbench surface dimensions are 2' x 3', the surface is 40% open and the air volume is 1000 cfm, then the face velocity is 1000cfm/((2x3)x .40) = 416.67 fpm.
Who's right? If it's them, then please explain. I contend that calculating the face velocity on the work surface of the down draft bench is no different than calculating the face velocity of a slotted ventilation hood (which is calculated using the area of the open slots on the hood).
We've got a steak dinner and drinks riding on this, so I'm looking forward to hearing your thoughts.
Thanks!
I contend that the true face velocity is calculated by by dividing the air volume by the total open slot area on the workbench surface. For example, if the workbench surface dimensions are 2' x 3', the surface is 40% open and the air volume is 1000 cfm, then the face velocity is 1000cfm/((2x3)x .40) = 416.67 fpm.
Who's right? If it's them, then please explain. I contend that calculating the face velocity on the work surface of the down draft bench is no different than calculating the face velocity of a slotted ventilation hood (which is calculated using the area of the open slots on the hood).
We've got a steak dinner and drinks riding on this, so I'm looking forward to hearing your thoughts.
Thanks!
RE: Down Draft Bench Face Velocity
My money is on a face velocity of 416.67 fpm.
RE: Down Draft Bench Face Velocity
RE: Down Draft Bench Face Velocity
RE: Down Draft Bench Face Velocity
RE: Down Draft Bench Face Velocity
RE: Down Draft Bench Face Velocity
RE: Down Draft Bench Face Velocity