Abstract: A sensor tube according to the present invention comprises: a tubular body for connecting two connection pipes to each other, wherein the two connection pipes are connected to a humidity sensor, so that the connection pipes transfer steam to the humidity sensor by using circulating air or air discharged from the humidity sensor flow in the connection pipes; and a cover surrounding at least a part of the outer surface of the body to prevent foreign substances having a predetermined size or larger from passing, wherein the body is formed as a porous sintered body which allows stream to be introduced from the outside of the body into the body and be transferred by the circulating air.

Abstract: A sensor tube according to the present disclosure includes a body including a body extension having opposite ends connected to measurement air connection pipes and an opening, the measurement air connecting pipes being connected to a humidity sensor to deliver moisture to the humidity sensor using measurement air or allow the measurement air released from the humidity sensor to flow therethrough, and the opening being formed in the body extension to cause an interior space of the body extension and the outside to be in communication with each other such that the moisture is introduced into the interior space of the body extension from the outside through the opening, and an opening/closing part that selectively opens or closes the opening by being operated by a difference in pressure between the interior space of the body extension and the outside.