Flowmeters can measure rate of flow or quantity of a moving fluid in an open or closed conduit. They are available in a variety of flow rate range. The height of the float in the flowmeter indicates flow rate. It consists of both primar and a secondary device.

Flue Gas Desulfurization (FGD) is a current state-of-the art technology used for removing sulfur dioxide (SO2) from the exhaust flue gases. This is employed in power plants that burn coal or oil to generate the steam for the steam turbines for driving electricity generators. Sulfur dioxide is responsible for acid rain formation. Tall flue gas stacks disperse the emissions by diluting the pollutants in ambient air. These FGD systems are custom designed to remove sulfur dioxide from flue gases using a variety of reagents such as caustic, lime, limestone, ammonia, fly ash, magnesium oxide, soda ash as well as seawater or double alkali.

The flue-gas ductwork system is placed between the boiler outlet and the chimney. There can be many large pieces of equipment in the system. For a coal-fired boiler when the outlet flue-gas passes through an air pre-heater, it is cooled. Then the cooled flue-gas is passed through an electrostatic precipitator or a fabric filter, which would result in the removal of the flyash particles from the flue-gas. Finally the sulfur is removed from the flue-gas with the help of ID fans and a flue-gas desulphurization system, or scrubber.

Flue Gas Recirculation Systems are used to measure temperature, capacitance, frequency and duty cycle measurements. It reduces nitrogen oxides (NOx) emissions (up to 60 percent) in industrial boilers by recirculating a portion of the boiler flue gas (up to 20 percent) into the main combustion chamber. It also reduces the peak combustion temperature and lowers the percentage of oxygen in the combustion air/flue gas mixture.