When natural gas expands from a higher to a lower pressure, its temperature can decrease. This phenomenon is significant in industrial regulating stations and can affect the operation of regulators and instruments.
What is the Joule–Thomson effect
During gas pressure reduction, the temperature may drop. The magnitude of the drop depends on the pressure, temperature, and gas composition conditions.
Potential problems
Low temperatures can affect diaphragms, pilot lines, small orifices, and instruments. If moisture is present, additional problems may arise due to cooling.
Symptoms
Unstable pressure, delayed response, regulator hunting, or unexplained variations under high load may be related to temperature effects.
What should be measured
Pressure and temperature before and after the regulator provide important information. Comparing measurements at different loads helps with diagnosis.
Solution
The solution is not always to replace the regulator. It may require gas preheating, changing the layout, or correcting operating conditions in accordance with the installation study.
