In extractive gas analysis it is important to protect the measuring cells from any type of contaminants. In addition to removing particle contamination, it’s also extremely important to separate moisture and condensation. Depending on the composition of the sample gas, a preseparator may also need to be installed upstream from the sample gas cooler. This reduces the load on the cooler when the moisture content fluctuates. In some applications removing the moisture with a preseparator and downstream coalescence filter may suffice. If the sample gas is pressurised, the pre-separators may be equipped with built-in automatic drain valves.