Abstract: A moisture (H.sub.2 O) measuring device for high temperature gas deriving the moisture content by taking a difference between measured values of oxygen concentration by an operational process. The one value of the an oxygen concentration is for oxygen content originally included in the measuring gas and the other value of the oxygen concentration is one additionally including oxygen content obtained by electrolysis of the moisture in the measuring gas. The two measured values are controlled by applying voltage for the oxygen pump.

Abstract: The disclosed sensor probe for detecting a gas component concentration such as an oxygen concentration has a specific gas introducing tube arranged in a gas probe tube, whose one end is faced to a gas sensor portion, and possessing a gas inlet hole for introducing a gas to be measured into the gas sensor portion through the gas introducing tube and a gas outlet hole for discharging the gas. Under such a construction, since a sufficient amount of a gas to be measured can be supplied effectively into the gas sensor portion even if a velocity of the gas is low, it is possible to maintain a high measuring accuracy.

Abstract: A combustion control apparatus of a combustion furnace by an improved fuel and air complementary control system according to master control system is disclosed, which is provided with a regulating means connected to a master controller and adapted for detecting the amount of load change and for setting the length of an air damper control rod's length changing device to a preset standard value corresponding to the load, without controlling the oxygen concentration in the exhaust gas to a standard value, when the load change is increased to a value of not lower than the preset value. The combustion control apparatus can control stably the oxygen concentration in an exhaust gas to a low level even when a load is suddenly changed.