| 摘要 |
PURPOSE:To accomplish safe operation accurately even at the oxygen starvation by means of two thermocouples arranged in a specified manner. CONSTITUTION:The first thermocouple 16 is arranged above the primary flame port 11 of a pilot burner 7 and the second thermocouple 17 is at a fixed distance above the main gas burner 3. With such an arrangement if the pollution of the air causes a drop in the oxygen concentration after the formation of the primary flame A at the primary flame port 11, the secondary flame B at the secondary flame port 8 and a flame C at the main gas burner 3, sensitively reacting to the drop, the primary flame A goes out while the flame C is lengthened due to the shortage of the oxygen. Consequently, as the primary flame A grows unstable, the thermal electromotive force of the first thermocouple 16 begins to reduce while the second thermocouple 17 slightly increases the thermal electromotive force as the flame C grows long. Thus, the difference in the electromotive force between the two thermocouples 16, 17 diminishes so much that a gas electromagnetic safety valve 5 is closed. Thereafter, the supply of gas is halted to ensure safety. |
