sentences:  Chilled mirror analyzers are subject to the confounding effects of some contaminants, however, usually no more so than other types of analyzers.With proper filtration and gas analysis preparation systems, other condensables such as heavy hydrocarbons, alcohol, and glycol need not impair the reliable function of these devices.It is also worth noting that in the case of natural gas, in which the afore mentioned contaminants are an issue, on-line analyzers routinely measure the water dew point at line pressure, which reduces the likelihood that any heavy hydrocarbons, for example, will condense before water.