Hi Steve - Seems sort of odd that the vendor told you to leave the system on at all times - did this vendor provide some logic for that instruction? My personal feeling is to turn the systems off over night, or into a low idle mode. As you've noted, solvent loss is a good reason, but I've had a couple of the do midnight boil offs due to control or sensor failures. Those type events can turn catastrophic in a hurry. Regards - Kelly ############################################################## TechNet Mail List 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://www.ipc.org/html/forum.htm) for additional information. If you need assistance - contact Gayatri Sardeshpande at [log in to unmask] or 847-509-9700 ext.5365 ##############################################################