A pressure gauge siphon is a simple device used to protect a pressure sensor from high-temperature media, such as steam. It can also be used to reduce the potentially damaging effects of rapid pressure changes. These low-cost devices allow systems builders to use a pressure sensor with a much lower temperature range in high-temperature applications.
When first installed the siphon should be filled with water or some other suitable separating medium. As seen in the diagram, condensation of the pressure medium collected inside the coiled portion of the siphon prevents direct contact with the external media.
A typical pressure gauge siphon like that shown in the diagram would be made from carbon steel, rated at 48bar (700psi) and suitable for a maximum temperature of 230ºC. However, siphons can be made from other materials to reduce costs. Extra coils can be added, and the pipes can be made longer or shorter to suit the requirements of the application.