Pumice would answer that requirement,=20
as would a brass float (heck depedning upon the diameter of the tube you =
could use a cartridge case with the base down.. providing it couldn't tip =
over in the tube, there would be no need to seal the top.

Des

>>> ardhuru@VSNL.COM 18/05/03 11:59:26 pm >>>
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=20

________________________________________________________________________
This email has been scanned for viruses by the CITEC Email Anti-Virus =
service powered by MessageLabs. For more information on a proactive email =
anti-virus service working around the clock, around the globe, visit =
www.citec.com.au=20
________________________________________________________________________


________________________________________________________________________
This=20email=20has=20been=20scanned=20for=20viruses=20by=20the=20CITEC=20E=
mail=20Anti-Virus=20service=20powered=20by=20MessageLabs.=20For=20more=20i=
nformation=20on=20a=20proactive=20email=20anti-virus=20service=20working=20=
around=20the=20clock,=20around=20the=20globe,=20visit=20www.citec.com.au
________________________________________________________________________

--
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