Abstract: A life indicator is so designed that an electric current flows to a light emitting diode utilizing a battery as a power source when two electrodes are electrically connected. The two electrodes are so installed as to be electrically connected by passing water through a water passage communicating with an objective equipment, and the discharge life of the battery is set equal to the service life of the equipment.

Abstract: The invention involves the detection of odors using an odor detector including an n-type semiconductor sensor having an electric resistance responsive to odor molecules adsorbed thereonto. An ozonizer is provided within a test compartment to contact the detector with an ozone gas for the purpose of calibrating the detector to an initial zero setting. The test compartment also includes a ventilation fan operable to draw purging air into the compartment. In order to minimize the time required to bring the detector to the initial zero setting, a computer is used to selectively actuate the ozonizer and the ventilation fan in a controlled manner. Before starting a new detection cycle, an operator selects a specific table of optimal pattern for quick recovery to the zero setting from among a plurality of tables stored in the computer, based on certain factors such as the identity and concentration of previously detected odorant substances, etc.

Abstract: The invention involves the measurement of the total concentration of odors of an article such as foodstuff, fruits and beverages as an indication of their specific quality such as freshness and maturity. An odorimetric device includes a non-selective odor detector disposed within an odorimetric chamber and a heater means for heating the odor detector to a predetermined operating temperature. The odor detector is comprised of a sintered body or film of a highly purified n-type metal oxide semiconductor formed on a substrate by vapor deposition. In one embodiment, the total concentration of odors of an object that is monitored as a function of time may be compared with a reference value or pattern to evaluate the quality of the object.