A tin oxide carbon monoxide sensor is operated in a manner to exclude effects of ambient temperature and humidity. Resistance of the sensor is measured at a lower temperature and again at a higher temperature. The target gas concentration is determined as a function of the first and second resistances, thereby cancelling the effects of humidity and ambient temperature.
A CO detector, utilizing periodical temperature change of a metal oxide semi-conductor gas sensor, is equipped with a backup battery. When power cut of a commercial power supply is detected, the detector will be driven by the battery, and the gas sensor will be heated at 50.degree.-100.degree. C. for from 30 seconds to 1 minute and will be kept at room temperature for about 30 minutes. CO is detected by the minimum sensor output after the heating.
There is provided a gas detector capable of detecting hydrogen concentration and humidity independently in the environment containing both hydrogen and water vapor. The gas detector comprises a high-temp exothermic detector unit and a low-temp exothermic detector unit provided with themosensitive resistors of different self-heating temperatures. The gas detector converts gas-level outputs produced by the high-temp exothermic detector unit and the low-temp exothermic detector unit responsive to the hydrogen concentration and humidity into electric signals, and outputs them after computing electrically levels of the hydrogen concentration and humidity contained in a gas introduced into the two detector units through a gas intake opening.
5416931 - Booth - Owned by Aromatherapy Steam Tube Company Limited (Shelf,GB3)
A booth, of general circular cross-section, includes a roof part 2, a base part and an intermediate part 6. The base is adapted to stand on the floor. Within the booth is a foldable chair 8. A person may gain access to the booth via a door 10 having a hinged edge 12 and a slide fastener 14. A steam kettle is provided below a false floor of the base part 4. In use, steam and aromatic vapor for essential oils is produced which fills the booth within which a person is seated.
A method of operating a gas sensor having two sensor electrodes whose output signal is evaluated in an evaluation circuit connected downstream of the sensor electrodes, the sensor electrodes being arranged in an ion-conducting ceramic and being therefor heated by an electrical heater, characterized in that a pulsewidth modulated heater voltage signal is applied to the heater; and that a compensation signal is superposed on the output signal of the sensor electrodes, the compensation signal being essentially formed so as to be counterclocked and inverted to the pulsewidth modulated heater voltage signal.
A gas detector and method of operating the gas detector that includes a carbon monoxide sensor and a processor. The carbon monoxide sensor senses an environmental concentration of carbon monoxide and provides the sensed value to the processor. Upon receiving the value of the carbon monoxide level (COppm), the processor determines an alarm threshold level based upon the COppm level. Once the alarm threshold level is determined, the processor calculates the COHb percentage for the current COppm reading based upon a derived, fixed point equation. The processor activates an audible/visual indicator when the sensed COHb percentage exceeds the alarm threshold.
