Abstract: Methods for utilizing transition metals as tracers in aqueous liquid systems are provided by this invention. Transition metals with low background levels in system waters are identified as preferred when soluble in said aqueous liquid systems. The transition metals show low levels of deposition on equipment scale and provide reliable information as to the process history of the liquid systems.

Abstract: Method and apparatus for determining accumulated film thickness at the inside diameter of a main stream conduit conducting a main stream of a flowing fluid by employing:a transparent shunt conduit to shunt from the main stream a sample stream of the process fluid,a reference light emitter and light detector at a reference section of the shunt where any appreciable film is removed, an upstream sample light emitter and detector opposed thereto,a common source of light so that respective emitters emit light beams of the same intensity, and means for determining concurrently analogs of light received by the detectors, whereby film thickness may be determined for the sample.

Abstract: Method and apparatus for measuring film formers in an opaque process stream by immersing a disc in the fluid stream, allowing time to accumulate film formers, then rotating the disc to expose the previously immersed section to optical monitoring by which a sample reflectance and a reference reflectance are compared.

Abstract: Analyzing the level of a treating agent and/or stress metals in a body of water containing an inert transition metal tracer added to the water proportionally with the treating agent by determining the absorbance (first absorbance value) of a reagent dye added to water, said dye producing a second absorbance value when reacted at the same concentration with the tracer and stress metals in a measure of said body of water, and said dye producing a third absorbance value when reacted at the same concentration with only the transition metal contained in a measure of said body of water; determining the second and third absorbance values and resolving their differences to determine the concentration of the tracer and, separately, the concentration of said stress metals.

Abstract: Analyzing the level of a treating agent and/or stress metals in a body of water containing an inert transition metal tracer added to the water proportionally with the treating agent by determining the absorbance (first absorbance value) of a reagent dye added to water, said dye producing a second absorbance value when reacted at the same concentration with the tracer and stress metals in a measure of said body of water, and said dye producing a third absorbance value when reacted at the same concentration with only the transition metal contained in a measure of said body of water; determining the second and third absorbance values and resolving their differences to determine the concentration of the tracer and, separately, the concentration of said stress metals.

Abstract: Continuous monitor to determine effective performance of a flocculant used to dewater a sludge stream, in which a voltage waveform of water clarity, generated by a sensor opposed to a light beam transmitted across the stream, is digitized by a comparator; the comparator is insensitive to sludge flow rate.

Abstract: Methods for utilizing transition metals as tracers in aqueous liquid systems are provided by this invention. Transition metals with low background levels in system waters are identified as preferred when soluble in said aqueous liquid systems. The transition metals show low levels of deposition on equipment scale and provide reliable information as to the process history of the liquid systems.

Abstract: An ion selective microelectrode in which the reference solution is an aqueous solution of formamide (or methyl formamide) and in which the ionophore-containing membrane covering the reference solution is PVC dissolved in water-insoluble 3-methylcyclohexanone (or equivalent substituted cyclic ketone). The reference solution may be gelled with PVA and preferably is buttressed to assure against incursion of membrane components.