Yeah, my washing machine uses this to 'control' the level of water used.
It's not very accurate, but in a washing machine who cares if it's a few
litres out?  But in a concrete plant the amount of water added controls the
workability, setting time and, to a degree, the final strength of the
concrete, so it *MAY* not be accurate enough.

Bye.

        -----Original Message-----
        From:   Patrick J [SMTP:info@DATECH.SE]
        Sent:   Thursday, 1 June 2000 5:48
        To:     PICLIST@MITVMA.MIT.EDU
        Subject:        SV:      Re: [EE][PIC] How to measure level of
liquids and sense relativehumidity?

        And how about another even simpler way ?
        (which might even prove to work in the real world!)

        Just stick a pipe down in the fluid and measure the air pressure
that
        builds in the pipe when the level rises. There are sensors availfor
it.