What Is a Bourdon Gauge Tube?
A Bourdon gauge tube is a pipe that is sealed at one end and designed with a flat cross-section. It was named after its inventor, E. Bourdon of France. This tube is commonly used in Bourdon gauge tube pressure gauges, and its principle is also applied in other measuring instruments such as barometers, differential pressure systems, and thermometers.
The shape of the Bourdon gauge tube changes in response to variations in pressure and temperature. The greater the movement, the higher the accuracy.
Bourdon gauge tubes are made from various materials, including brass, aluminum brass, stainless steel, phosphor bronze, and other highly elastic alloys. For high-precision pressure measurement, beryllium copper and nickel span are especially used.
Uses of Bourdon Gauge Tubes
The primary use of Bourdon gauge tubes is in pressure gauges. These gauges, known as Bourdon pressure gauges, are simple in construction, easy to use, and don’t require external energy such as electricity. They can measure a wide range of pressures, from vacuum to approximately 200 atmospheres.
Bourdon gauge tube thermometers, which operate on the same principle as the Bourdon gauge tube pressure gauges, are also widely used in industry. These thermometers measure temperature through the expansion and contraction of a liquid or gas sealed inside the Bourdon tube. Advantages of Bourdon tube thermometers include the ability to keep the indicating part distant from the temperature-sensitive part, suitability for high-temperature measurements, a simple and trouble-free structure, and no need for external energy.
Principle of Bourdon Gauge Tubes
When a Bourdon gauge tube is used in a pressure gauge, a curved Bourdon tube is connected to the measuring point. The tube extends with increased pressure and bends with decreased pressure. In a thermometer, a liquid such as alcohol is sealed inside the tube; the tube expands with rising temperatures, causing the liquid level to move. This movement indicates the temperature change. By varying the material and thickness of the Bourdon gauge tubes, a wide range of accuracy and measurement conditions can be accommodated.
However, the typical structure of a Bourdon gauge tube pressure gauge can be problematic when used with corrosive media, as the pressure-receiving medium is in direct contact with the Bourdon tube. In environments with vibration or fluctuating pressure, accuracy issues can arise. To address these issues, diaphragm pressure gauges that incorporate a diaphragm between the Bourdon tube and the pressure-sensing medium, and glycerin-filled gauges that contain glycerin inside to mitigate the effects of vibration and pulsation on the Bourdon tube are also used.