Abstract: A gas meter comprises a conduit for passage of a gas flow and an ionizer to ionize the gas flow. A modulating electrode structure downstream of the ionizer modulates the ion distribution in the ionized gas flow. A first and a second electrode structure downstream of the modulating electrode structure detect the ion distribution in the ionized gas flow. The modulating electrode structure and the detecting electrode structure can generate an electrical field parallel to the direction of the gas flow. The modulating electrode structure and the detecting electrode structures can each have apertures defined therein for passage of the gas flow. The modulating electrode structure can capture ions of one polarity to generate an ionized gas flow comprising a majority of ions of the opposite polarity. Movement of the ionized gas flow generates a current indicative of the ion distribution between the electrode and the charge source.

Abstract: A method of measuring chlorine concentration of a solution comprising making a first measurement of transmission of ultraviolet light at a selected wavelength through a first sample of said solution at a first temperature; making a second measurement of the transmission of ultraviolet light at said selected wavelength through a second sample of said solution at a second temperature, said second temperature being different than said first temperature; and determining the chlorine concentration in said solution using the results of said first and second measurements.

Abstract: A method of measuring the free chlorine level in a solution of chlorinated pool/spa water comprises a first sample of said solution having a first selected pH and a second sample of said solution having a second selected pH and determining first and second ultraviolet light (UV) transmissivity values for each of the first and second samples. The first and second transmissivity values are then used to determine the free chlorine level.

Abstract: An apparatus for use in measuring the free chlorine level in a solution of halogenated pool/spa water includes a pH adjusting device for producing a first sample of said solution having a first selected pH and a second sample of said solution having a second selected pH, as well as a spectral analyzer for determining first and second ultraviolet light (UV) transmissivity values for each of the first and second samples. An electronic processor receives the first and second transmissivity values and determines the free chlorine or bromine level using those values.

Abstract: A method of measuring chlorine concentration of a solution comprising making a first measurement of transmission of ultraviolet light at a selected wavelength through a first sample of said solution at a first temperature; making a second measurement of the transmission of ultraviolet light at said selected wavelength through a second sample of said solution at a second temperature, said second temperature being different than said first temperature; and determining the chlorine concentration in said solution using the results of said first and second measurements.

Abstract: An apparatus for use in measuring the free chlorine level in a solution of halogenated pool/spa water includes a pH adjusting device for producing a first sample of said solution having a first selected pH and a second sample of said solution having a second selected pH, as well as a spectral analyzer for determining first and second ultraviolet light (UV) transmissivity values for each of the first and second samples. An electronic processor receives the first and second transmissivity values and determines the free chlorine or bromine level using those values.

Abstract: A method of measuring the free chlorine level in a solution of chlorinated pool/spa water comprises a first sample of said solution having a first selected pH and a second sample of said solution having a second selected pH and determining first and second ultraviolet light (UV) transmissivity values for each of the first and second samples. The first and second transmissivity values are then used to determine the free chlorine level.