Abstract: A system utilizing the flow cell of the present invention includes a reflectance mode spectrophotometer positioned with respect to the flow cell or a probe. Either the flow cell or the probe has a thin partition mounted in spaced relationship with respect to a transparent window. The partition has a predetermined index of refraction and has a thickness dimension that is less than that of the window. The spacing between the partition and the window is such that evanescent coupling of radiation reflected from the liquid into the material of the window is prevented. The spectrophotometer directs interrogating radiation toward a liquid flowing through the sample chamber and responds to interrogating radiation reflected from the liquid to produce an electrical signal representative of a color property thereof.

Abstract: A flow cell for measuring the color properties of a liquid flowing therethrough using interrogating radiation at a predetermined wavelength has a thin partition mounted in spaced relationship between both a window and a base of the cell. The partition and the window define an air cavity therebetween. The spacing between the partition and the window is such that evanescent coupling of radiation reflected from the liquid into the material of the window is prevented. The cell has a pressurized fluid inflow channel and a pressurized fluid outflow channel formed therein. Each of the inflow and outflow channels communicates with the air cavity. The inflow and outflow channels are sized to pass a pressurized fluid, such as pressurized air, through the air cavity such that, in use, the spaced relationship between the partition and the window is maintained by pressurized fluid in the air cavity.

Abstract: A flow cell for measuring the color properties of a liquid flowing through the flow cell using interrogating radiation at a predetermined wavelength has a thin partition mounted in spaced relationship between both a window and a base of the cell. The partition has a predetermined index of refraction and has a thickness dimension that is less than that of the window. The spacing between the partition and the window is such that evanescent coupling of radiation reflected from the liquid into the material of the window is prevented. Typically, this spacing is a distance not less than three (3) times the predetermined maximum wavelength in the wavelength range of interrogating radiation. A plurality of spacer elements may be disposed in the air cavity to maintain the spaced relationship between the partition and the window. The flow cell has a liquid supply passage and a liquid removal passage formed therein.