What protects the Bourdon tube in a pressure gauge installed between the boiler and the gauge?

The Bourdon tube in a pressure gauge functions based on the principle that when pressure is applied to the inside of the tube, it tends to straighten out from its initial curved position. This movement is what allows the gauge to indicate the pressure level accurately.

In the context of a pressure gauge that is installed between the boiler and the gauge, the use of steam as a protective medium is ideal. Steam is typically at a high temperature and works effectively to transmit pressure without causing significant thermal shock or damage to the components of the gauge. Furthermore, steam can provide a degree of protection against pressure spikes that may occur, ensuring the durability and reliability of the gauge over time.

Using substances like water, oil, or air in this specific application would not be as effective. Water could lead to condensation inside the gauge, which may affect the accuracy and functionality. Oil might be utilized in other applications, but it can pose problems such as viscosity changes with temperature fluctuations. Air, while it can transmit pressure, does not provide the same level of protection and performance in high-temperature environments typical of boiler operations. Therefore, steam is the most suitable choice for safeguarding the Bourdon tube in this scenario.