The problem becomes a lot easier if you can attach a larger tube alongside the sight glass for a more reasonable sized float. Boiling water is not that hot, even a toilet tank mechanism might be adapted to the task. Sometimes low tech is a better solution... John Ferrell 6241 Phillippi Rd Julian NC 27283 Phone: (336)685-9606 johnferrell@earthlink.net Dixie Competition Products NSRCA 479 AMA 4190 W8CCW "My Competition is Not My Enemy" ----- Original Message ----- From: "Anand Dhuru" To: Sent: Sunday, May 18, 2003 9:59 AM Subject: Re: [OT]:Material that floats in water, yet withstands heat There is an industrial water boiler, with a pump that is switched manually to maintain water inside between two levels. The temperature of the water inside the boiler is maintained close to the boiling point. There is a transparent glass tube (about 1cm in diameter) that is hydraulically coupled to the boiler, to give a visual indication of the water level. This indication is used by an operator to switch the pump manually, at present. Now, I am trying to design a simple optical arrangement to detect the minimum and maximum levels, which would drive the PIC, and the software within to switch the pump at appropriate times. The problem is, what material can I possibly use that would float in water, and yet withstand very high temperatures on a long term basis? I could just drop a pellet of the stuff in the indicator tube, and then mount the minimum / maximum IR sensors on the tube externally, if I find the right material. Thanks and regards, Anand Dhuru -- http://www.piclist.com hint: The list server can filter out subtopics (like ads or off topics) for you. See http://www.piclist.com/#topics -- http://www.piclist.com hint: The PICList is archived three different ways. See http://www.piclist.com/#archives for details.