Processes are often set-up on one continent and expected to be a carbon copy set-up on another continent. What do you think is going on when the end result doesn’t turn out this way? The answer: environmental factors. Play the detective and characterize your facility!
What is Going On with your Exhaust?
At first glance, the exhaust stack on the reflow oven looks simple enough. Its purpose is to remove excess heat and the occasional vapor that escapes from the reflow chamber. What happens when the CFM or CMM is set higher than that of the designed setting? How stable is the flow of exhaust? Does it increase or decrease when other equipment in the facility is added, started or stopped?
I bet you have no idea and how could you? Most facilities do not install site gauges. Most facilities add equipment monthly. Changes occur to the barometric pressure outside the facility and fans accumulate all kinds of crud. I have seen 6 inch exhaust ducts blocked more than 4 inches.
This is not to make you tear apart every duct, but be aware that many factors can change the setting of the exhaust. It is not likely that a single variable will crash your process. You should, however, check the exhaust flow on occasion and certainly after changes are made to the system during maintenance.