Patent ID: 7216527

Claim:
A gas detector comprising a sensor configured to alternately introduce a reference gas and a test gas into the sensor, within an enclosure for detecting a particular component contained in the test gas, the gas detector characterized by that a source of supply of the reference gas is installed within the enclosure and the test gas is taken in from outside the enclosure, said gas detector further comprising: an intake/exhaust mechanism for taking in or exhausting a gas by expansion or contraction of inner space thereof; a passage of the reference gas or the test gas communicating with the intake/exhaust mechanism; a source of supply of the reference gas for use in determination of a zero level of the test gas at the detection; the sensor for use in measurement on the reference gas and the test gas; and a controller for performing at least one of processing of output data from the sensor and controlling of operation of each unit; wherein the test gas or the reference gas is supplied to the sensor by intake/exhaust motion of the intake/exhaust mechanism, and a particular component in the test gas is identified in accordance with strength of a measured signal; wherein the reference gas or the test gas is introduced into the sensor by reciprocating motion of a piston of a cylinder mechanism formed of the piston and the cylinder in combination; wherein, when a gas is taken in, a one-way valve for allowing the gas to flow only in one direction from the sensor to the cylinder mechanism is used and, when the gas is exhausted, another one-way valve for allowing the gas to flow only in one direction from the cylinder mechanism to an exhaust port is used.