[c-nsp] Enclosed rack with filtered air

[scott owens]

Hello,
   I need to put two 6509s in a non-clean warehouse.  I thought I could just
put them in a standard rack with some AC filters attached to the bottom and
let the air get pulled out of the top.  However the rack is not airtight
enough and I am getting a lot of drywall/dust in the rack and switches.

Anyone here know where / how to find a semi-sealed enclosed rack with
filtered forced air  ?