Pressure gauge siphons are used to protect the pressure gage from the effect of hot pressure media, such as steam and also, which threaten the effect of rapid pressure surges. The pressure medium is concentrated and stored within the siphon section of the pigtail.
The condensate avoids direct contact with the pressure instrument by the hot media. It should be filled with water or any other appropriate separating liquid when the siphon is first mounted.
The siphon is separated with liquid or any other suitable separating medium. As seen in the diagram, the condensation of the pressure medium collected within the rolled portion of the siphon prevents direct contact with the external means.
A typical siphon pressure gauge is made of carbon steel, rated at 48bar (700psi) and suitable for a maximum temperature of 230°C. However, to reduce costs, siphons can be made from other materials. It is possible to add extra coils, and the pipes can be made longer or shorter to suit the application requirements.
It acts as a cooling coil and by dissipating heat, it protects the gage against high temperature vapors. Generally, a gage cock is connected for isolation between the pressure gage and the syphon.
Protection from pressure spikes and pulsations
Direct process contact or in conjunction with other instrument accessories