Method and apparatus for detecting water on a surface of an object

An apparatus for non-invasive detection of water on a strip of steel in combination with a rinse section of a steel treatment facility, said strip of steel being conveyed along said rinse section between a drying stage area and a coiler, said apparatus comprising:

• a) a detection assembly provided to detect a presence of water on said strip and positioned along said rinse section between said drying stage area and said coiler proximate a roller supporting a turn in said conveyed strip, said detection assembly including;
• b) an infrared light source including a pair of quartz infrared heaters disposed above said strip, said heaters having a parabolic reflector to illuminate an entire width of said strip by infrared radiation;
• c) a detection box disposed between said pair of quartz infrared heaters and disposed above said strip to detect a reflected portion of said infrared radiation reflected off said strip, said detection box including;
• d) an infrared sensor including an arsenide photovoltaic infrared diode sensitive to infrared wavelengths within a range from 1 to 3.5 microns and producing a first signal representative of an intensity of said reflected portion of said infrared radiation;
• e) an optical filter disposed between said infrared sensor and said strip limiting transmission of said reflected infrared light to a range from 2.7-2.9 microns;
• f) a lens disposed between said optical filter and said infrared sensor to focus said reflected light onto said sensor;
• and
• g) an amplifier receiving said first signal and producing therefrom an amplified voltage signal representative of said intensity of said reflected portion of said infrared radiation.

A non-invasive method of detecting water on a surface of an object, said method comprising the steps of:

• directing an infrared light having a wavelength substantially absorbed by water onto a select area of said object;
• sensing a reflected portion of said infrared light from said select area to determine an intensity thereof;
• and
• determining the presence of water on said selected area by comparing said intensity to a predetermined value.

A method of non-invasively detecting water on a surface of a moving strip of metal conveyed along a rinse section of a manufacturing assembly, said method comprising the steps of:

• conveying said strip of metal along said rinse section between a drying stage area and a coiler of said rinse section;
• directing an infrared light having a wavelength substantially absorbed by water onto said strip;
• filtering said infrared light to limit transmission thereof to within a range of wavelengths from 2.7 to 2.9 microns;
• sensing a reflected portion of said infrared light reflected off said select strip to determine an intensity thereof, and producing a first signal representative of said intensity of said reflected portion of said infrared light;
• amplifying and converting said first signal to a second voltage signal;
• and
• determining the presence of water on said strip area by comparing said second voltage signal to a predetermined threshold value;
• wherein, said step of directing said infrared light and said step of sensing said reflected portion of said infrared light occurring at a location between said drying stage and said coiler proximate a roller supporting a turn in said conveyed strip of metal.

A method of detecting water on a surface of a metal sheet, comprising the steps of:

• directing radiant energy having a wavelength substantially absorbed by water onto a surface target area of said metal sheet;
• sensing a reflected radiant energy from said surface target area to determine an intensity thereof;
• and
• determining a presence of water on said surface target area by comparing said intensity to a predetermined value.