Thermal mass flowmeters are an important element of the emissions control process; specifically in the measurement of mass emissions. Application of the thermal flowmeter is useful for owners or operators of facilities that emit GHGs (Greenhouse-gases) to monitor and report annual mass emissions.
The thermal flowmeter’s most important attribute is its ability to directly measure mass flowrate without temperature and pressure compensation. Because it has no moving parts and can be installed via a single insertion point on a pipe or duct, it is easy to install and maintain. The instrument’s broad measurement range also makes it ideal for monitoring very low velocity flowrates, such as those found in vent gas, flare, and fugitive emissions applications.
Most thermal flowmeters also incorporate a totalizer and digital communications for interfacing with emissions management systems and can be used to monitor GHG emissions from industrial, institutional, and commercial boilers.
http://www.flowcontrolnetwork.com/applications/energy/article/q-and-a-key-trends-in-emissions-monitoring-and-control