单项选择题
A.Carry out soot blowing if permissible
B.Change fuel supply to diesel oil
C.Close steam stop valves on boiler when pressure is reduced
D.Drain boiler empty when it has cooled down
单项选择题 The forced draught fan should be started and air passed through the furnace for several minutes to “（）” it of any exhaust gas or oil vapors.
单项选择题 A shallow dish positioned at the normal water level is connected to the（）This enables the blowing down or removal of scum and impurities from the water surface.
单项选择题 The（）enables water to be blow down or emptied from the boilerIt may be used when partially or completely emptying the boiler.