High velocity of the pipe should use the thermometer?

In many specific use environment, such as underground pipes or some sealed container, the work environment itself has a certain pressure, if you want to measure the temperature of the inside, what kind of thermometer should be used? Today let's internal 40 kg pressure working environment, for example, said the problem. First we need to know, work environment if 40 kg pressure, if inserted the thermometer measured liquid, may be due to the large pressure, lead to deformation temperature measuring instruments. In this way, the part of the heat of the thermometer pressure ability is required. So, in the work environment we will choose 40 kg pressure with a sheath of bimetallic thermometer for temperature measurement, it is a kind of special measure 50 to 500 c/F field instruments, its main component is a use two or more pieces of metal laminate composed of multilayer metal together, using two different metal working in the principle of expansion degree of different temperature changes. When the temperature changes, the resulting thermal devices the free end of the rotation, drive the thin axis from the Angle of the pointer changes, corresponding temperature indicator on the dial.