Abstract: An embodiment provides a method for measuring dissolved oxygen of an aqueous sample, including: introducing an aqueous sample into a measurement device comprising at least two dissolved oxygen sensors, wherein at least one of the at least two dissolved sensors comprises a trend sensor and at least another of the at least two dissolved sensors comprises a reference sensor; measuring a first value of dissolved oxygen using the trend sensor, wherein the trend sensor samples at a trend frequency; measuring a second value of dissolved oxygen from a reference sensor, wherein the reference sensor samples at a reference frequency, the reference frequency being less than the trend frequency; and correcting the first value of dissolved oxygen based upon the second value of dissolved oxygen. Other aspects are described and claimed.

Abstract: An embodiment provides a method for measuring dissolved oxygen of an aqueous sample, including: introducing an aqueous sample into a measurement device comprising at least two dissolved oxygen sensors, wherein at least one of the at least two dissolved sensors comprises a trend sensor and at least another of the at least two dissolved sensors comprises a reference sensor; measuring a first value of dissolved oxygen using the trend sensor, wherein the trend sensor samples at a trend frequency; measuring a second value of dissolved oxygen from a reference sensor, wherein the reference sensor samples at a reference frequency, the reference frequency being less than the trend frequency; and correcting the first value of dissolved oxygen based upon the second value of dissolved oxygen. Other aspects are described and claimed.

Abstract: A wireless signal is propagated via a communication channel and received by a vent stop. The vent stop, upon receiving and decoding the signal, conducts an electric current to release the vent stop from a plumbing vent. In one embodiment, an intralumen audio signal is communicated to the vent stop and an adhesive joint securing the vent stop to the vent pipe is released upon passing an electric current through the joint. In one embodiment, an electric motor or solenoid releases the stop from the vent pipe. A spring or other energy storage device ejects the stop from the vent pipe following release.