Hydrogen is used as a coolant in generators because it is the most efficient cooling agent available. It has the highest thermal conductivity of all gases, allowing it to quickly draw heat away from the stator. A secondary benefit of using hydrogen is its low density, which reduces drag on the brushes, making the generator work more efficiently. High purity hydrogen is required for the effective cooling and safe operation. Because it is not possibly to hermetically seal the generator set casings, there is always the potential for moisture ingress from the surrounding air. Too much moisture in the system reduces efficiency and introduces the risk of arcing and damage to the generator. Too much oxygen could cause an explosion. Designed for use with hydrogen-cooled generators, Model XTC601 has three phase profiles to cover all of the gas analysis requirements for operation and maintenance.