Dear K.Chokchai,
Roots cause dusty come out from old blower big grinding machine , which we will action as below
Temporary action
1) selling silicon blower with block leak hold first
2) selling silicon of ceiling with block leak hold
Will send PO with you approved and give supplier repair on this Saturday
Permanence Action
We will propose buy new blower with improvement source of problem
now on process consider supplier with compare cost.
If you have any question or advise please contact to me.