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Shakkottai P Venkateshan

Parthasarathy Shakkottai

Daniel D Lawson

The polymer hygrometer with lithium doped Nafion was developed to meet the need for a reliable sensor for determining the relative humidity in harsh environments of pulp and paper mills. The sensor can operate in atmospheres that have organic vapors and dust, is unaffected by sulphur dioxide, acidic vapors and strong oxidizing agents. Exceptional stability is shown by the sensor which has withstood twelve months of continuous operation in a paper mill drier duct at temperatures near 65.degree. C. and air flow velocity of 10 m/s with no degradation or calibration change. Materials used in construction of the sensor such as glass, silver filled epoxy, Teflon, platinum wire, and Nafion contribute to ruggedness and immunity to harsh environments.

Polymer hygrometer for harsh environments

Measurements of the times of flight of sound waves can be used to determine temperature in a gas contained in a long tube which confines sound waves. Sound pulses are transmitted and received by a suitable loud speaker attached to one end of the long tube. A number of stubs or other discontinuities produce the sound reflections whose times of arrival are measured. The time intervals yield average sound speeds in each interval between any two stubs from which temperatures are calculated. Corrections for thermal expansion of the tube are easily made.

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Madras, India

Shakkottai P Venkateshan