Abstract: Provided is a sensor unit including a first sensor portion that detects deformation of a measuring target object and a second sensor portion that detects deformation of the measuring target object, in which in a state in which the first sensor portion and the second sensor portion are attached to the measuring target object, the first sensor portion and the second sensor portion are fixed to the measuring target object such that the measuring target object is disposed between the first sensor portion and the second sensor portion in a first direction, and a physical property value of the first sensor portion and a physical property value of the second sensor portion are changed according to first deformation of the measuring target object.

Abstract: A vacuum/reduced pressure refining vessel (1) is connected, by an upstream duct (5) to a dry dust collector (3) that uses a filter (2). The dry dust collector (3) is connected to a reduced pressure evacuating apparatus (4) by a downstream duct (6), and a block valve (7) is provided in the upstream duct (5). At the start of a vacuum/reduced pressure refining treatment, a non-oxidizing gas is injected into the upstream duct at a position that is upstream of the block valve (7) to substantially replace the oxygen in the upstream duct and to hermetically close the upstream duct. After the hermetically closed state has been established in the upstream duct, the block valve (7) is opened and operation of the dry dust collector (3) is started.