What liquid is commonly used in a wet leg compensating line to prevent vapor issues?

In instrumentation and level measurement applications, a wet leg compensating line is used to ensure accurate readings in situations where vapor might interfere with the measurement. Glycol is often chosen as the liquid for this purpose because it has a suitable density and a low vapor pressure, which minimizes the likelihood of vapor formation.

Using glycol in a wet leg setup helps maintain a consistent liquid column that can compensate for pressure changes or variations in the process environment. Its chemical properties make it more stable and less volatile than some other liquids, which further reduces the chances of vapor issues that might skew measurement readings.

While water can also be used in some contexts, it is more prone to vapor issues at higher temperatures, making it a less reliable choice in environments where precision is critical. Similarly, liquid nitrogen and oil have different characteristics that may not be as beneficial for preventing vapor interference in the context of level measurement in a wet leg setup.