Suction pyrometers consist of a combination of a thermocouple and a suction probe for gas samples, with which the temperature of the extracted gas flow can be measured. The fuel gas/flue gas is sucked to the tip of the suction pyrometer, and passes a type B thermocouple. This increases the heat transfer coefficient through forced convection, thereby improving the responsiveness of the temperature measurement. The thermocouple is shielded by a three layered ceramic radiation shield, to block unwanted influences through radiation. The pyrometer also has a water cooling system for the lance. The attainable exactitude with this measurement lies at a deviation of very few K. With this measurement method, local flame temperatures of up to 1800 °C can be determined.