Measurement of the concentration of solids in fluids

Claim 1

An apparatus for determining the concentration of solids in suspension in a chamber, and apparatus comprises (a) a lamp producing a single beam of light, (b) a measurement chamber of generally cylindrical shape which is adapted to contain a quantity of said suspension and to admit thereinto only said single beam of light from said lamp and the end wall of which is in the direct water, the of said beam of light from said lamp and is provided with a weakly light-reflecting surface, (c) a first photocell adapted to receive light originating from said lamp and reflected through an angle of 180* by solid particles in the suspension and to produce a signal proportional to the intensity of the reflected light, (d) second photocell arranged to receive light directly thereon from said lamp and to produce a signal proportional to the intensity of the light, (e) a neutral optical filter which is disposed between the second photocell and said lamp so that the intensity of the light received by the second photocell is of the same order as that received by the first photocell, (f) a measuring head which houses the lamp, the first photocell, the second photocell and the neutral optical filter, and which includes a window through which said single beam of light can be directed, the measuring head being mounted in the region of the other end wall of the cylindrical measurement chamber, and (g) means for comparing the signals produced by the first and second photocells as a function of the solids concentration of the suspension in the measurement chamber; the power of the lamp, the length of the measurement chamber and the light-reflecting ability of said weakly light-reflecting surface being such that, if the measurement chamber contains pure water, the signal produced by the first photocell corresponds to that which would be produced if the measurement chamber were of infinite length and contained about 10 p.p.m. of suspended solids.

Claim 2

An apparatus for determining the concentration of solids in suspension in a chamber, and apparatus comprises (a) a lamp producing a single beam of light, (b) a measurement chamber of generally cylindrical shape which is adapted to contain a quantity of said suspension and to admit thereinto only said single beam of light from said lamp and the end wall of which is in the direct water, the of said beam of light from said lamp and is provided with a weakly light-reflecting surface, (c) a first photocell adapted to receive light originating from said lamp and reflected through an angle of 180* by solid particles in the suspension and to produce a signal proportional to the intensity of the reflected light, (d) second photocell arranged to receive light directly thereon from said lamp and to produce a signal proportional to the intensity of the light, (e) a neutral optical filter which is disposed between the second photocell and said lamp so that the intensity of the light received by the second photocell is of the same order as that received by the first photocell, (f) a measuring head which houses the lamp, the first photocell, the second photocell and the neutral optical filter, and which includes a window through which said single beam of light can be directed, the measuring head being mounted in the region of the other end wall of the cylindrical measurement chamber, and (g) means for comparing the signals produced by the first and second photocells as a function of the solids concentration of the suspension in the measurement chamber; the power of the lamp, the length of the measurement chamber and the light-reflecting ability of said weakly light-reflecting surface being such that, if the measurement chamber contains pure water, the signal produced by the first photocell corresponds to that which would be produced if the measurement chamber were of infinite length and contained about 10 p.p.m. of suspended solids.