What is a movable external thread bimetallic thermometer

Bimetallic thermometer is everywhere in our daily life, what do you know that is moving outside thread bimetallic thermometer? Actually moving outside thread bimetallic thermometer is a kind of bimetallic thermometer, as shown in the figure below, it means the installation for movable threaded bimetallic thermometer. Movable external thread compared with the fixed screw is one of the difference of fixed thread by thread end face seal, the movable card casing thread depends on the axial sealing ring seal; Advantage is fixed card set of thread header and thread connection point is fixed, the entire header when installation with screw rotation, and the movable external thread header when installation and threaded connections are active. This advantage is also based on its application scenario arises at the historic moment. For movable external thread bimetallic thermometer is commonly used on large equipment, imagine we put double metal on the device, a screw tight after a big possibility of its header is not just the vertical to the ground, our reading is not so convenient, and if it is moving to use external thread bimetallic thermometer, after installed, we are free to adjust the position of a good header, and then should be fixed to live, so we usually reading is very convenient.