Bimetallic thermometer why oil filled?

Our common bimetallic thermometer is used to distinguish to the environment, the common radial, axial and universal type three kind of bimetallic thermometer, occasionally we will see to the three kinds of bimetallic thermometer oil-filled, that do you know why the bimetallic thermometer to oil filled? Actually give the bimetallic thermometer header filled with silicone oil or glycerin, mainly to have the effect of seismic. We will put all in oil filled thermometer is also called seismic thermometers, it is also can be directly measured various - in the process of production 50 ℃ ~ + 500 ℃ range of liquid, steam and gas medium and places bad environment and the temperature of the vibration. Production process, we oil filled from inside the instrument, which can effectively overcome the mechanical vibration of pointer jitter. On the design principle and structure of a waterproof, corrosion resistance, vibration resistance, intuitive, easy reading, no mercury pollution, durable and other characteristics, widely used in petroleum, chemical industry, machinery, ships, electricity, textile, printing and dyeing and other industrial and scientific research departments. Its main characteristic is: ( 1) Site display temperature, intuitive and convenient, safe and reliable, long life; （ 2) Many kinds of structure forms, can meet different requirement, no mercury pollution, easy reading, strong shock resistance; （ 3) Protection is 1 gr18ni9ti stainless steel and molybdenum titanium tubes, pressure and corrosion ability;