The working characteristics of the pressure type thermo […]
The working characteristics of the pressure type thermometer are generally determined by the filling material. When the filling material is gas (usually nitrogen), the pressure coefficient of nitrogen can be approximately regarded as an ideal gas. The relationship between pressure and temperature is linear, so the indicating scale is a linear uniform scale.
The main structure of the pressure thermometer:
1. Warm bulb: It is a component that directly contacts the measured medium to sense temperature changes, so it is required to have high strength, small expansion coefficient, high thermal conductivity and corrosion resistance. Depending on the working substance charged and the measured medium, the bulb can be made of copper alloy, steel or stainless steel.
2. Capillary: It is a seamless round tube cold drawn from copper or steel and other materials to transmit changes in pressure. Its outer diameter is 1.5~5mm, and its inner diameter is 0.15~0.5mm. If it is thinner in diameter and longer in length, the hysteresis in transmitting pressure will be more severe. That is, the more sluggish the pressure thermometer is to the temperature being measured. However, at the same length, the thinner the capillary, the higher the accuracy of the meter. Capillaries are easily broken and broken, so they must be protected. Metal hoses can be used as protective sleeves for capillaries that are not often bent.
3. Spring tube: It is an elastic element used in general pressure gauges.
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