Gas indicator and gas sensor sheet

摘要

The invention designed to provide a gas indicator which can be applied over a broad range of gas concentration from a low concentration gas to a high concentration gas is concerned with a gas indicator comprising a housing and a change-color gas sensor element with which the housing is loaded, the housing internally defining a gas passage space extending from its gate through its bottom with the area of its cross-section parallel to the plane of the gate being progressively reduced from the gate to the bottom.