Steve, In a past job, we used to tie multiple reflow ovens to the same blower without too many problems. Balancing the flows for everything is the biggest pain. Another reply made a point about if your blower goes down, it shuts down your operation. Perhaps having more than one blower would make sense for that reason. Some of the blowers we had were pretty long lead time items. For horizontal ducting, we used to put a drain tube with a sight glass at the lowest spot on the slope. This would allow us to see if there was any liquid build-up, and periodically drain the ducts if necessary. As for the toxic substances... From my plating days, I know it is probably not a good idea to mix an acid cleaning bath exhaust with a gold cyanide plating bath exhaust, but I haven't heard of any deadly reactions from soldering and cleaning exhaust mixing. Most of the time with water condensation, I think it is probably concentration of acids, bases, or explosive substances (solvents, etc.) that is worrisome from a corrosion or maintenance safety standpoint. Perhaps your solder/flux supplier can provide some insight / references. Good Luck, Dave Anderson Medtronic, Inc. Opinions are my own, worth what you pay for them, and do not necessarily reflect those of my employer. ################################################################ TechNet E-Mail Forum provided as a free service by IPC using LISTSERV 1.8c ################################################################ To subscribe/unsubscribe, send a message to [log in to unmask] with following text in the body: To subscribe: SUBSCRIBE TechNet <your full name> To unsubscribe: SIGNOFF TechNet ################################################################ Please visit IPC web site (http://jefry.ipc.org/forum.htm) for additional information. For the technical support contact Dmitriy Sklyar at [log in to unmask] or 847-509-9700 ext.311 ################################################################