Monitoring hydrogen (and nitrogen) in solar cell manufacturing is an important part of the quality control in polysilicon manufacturing. In-Line Thermal Mass Flow Meters do not require separate temperature and pressure measurement, have fast response time, and low pressure drop. They are important instruments for controlling and monitoring the process of polysilicon manufacturing. Other hydrogen applications where Thermal Mass Flow meters are used include: measuring the flow rate to hydrogen reactors in batching operations and in gas distribution systems, and also, monitoring the hydrogen flow (used to cool the turbines) to detect leaks in the plant turbine generators. Hydrogen, along with other gases, such as Argon and Helium, can also be used in heat treating where its measurement is required.