Abstract: A pair of reference electrodes and a flame rod are placed in contact with charged particles in a flame produced by a burner. When a voltage is applied between the flame rod and the burner by a power source, a current (I.sub.fr) flows between them due to the flame conductivity. A potential difference (V.sub.12) between the pair of reference electrodes is detected by a potential difference detector. The dynamic flame impedance between the pair of reference electrodes is defined as the slope of the I.sub.fr -V.sub.12 relationship and is independent of I.sub.fr.

Abstract: A double-cylinder type oil burner having an inner flame cylinder and an outer flame cylinder. A red-heatable cylinder is connected to the upper end of the inner flame cylinder with a secondary air inlet left therebetween. A damper mechanism for varying the opening in the upper end of the red-heatable cylinder is provided on the upper end of the red-heatable cylinder. According to this arrangement, it is possible to vary the burning rate over a wide range and to vary the red-heated area in accordance with the rate of burning.

Abstract: A combustion device has a negative pressure combustion burner and an ejector air flow generating mechanism and is designed so that the warm air flow rate is approximately proportional to the combustion rate. The device is simple in construction, and by controlling the warm air flow rate it is possible to adjust the heat output of the device while maintaining the temperature of warm air at a constant value. The device disclosed herein is particularly suitable for use as an air circulation type room heater.

Abstract: A liquid fuel burner for burning liquid fuel in the form of a gaseous mixture with air. The liquid fuel burner has a porous member provided at least with a fuel receiving section for receiving the liquid fuel supplied to the burner and a fuel evaporation section from which the liquid fuel is evaporated. An air supplying device is provided for forcibly supplying air to the fuel evaporation section. The rate of air supply is varied by means of a damper or like means. Heating means are provided for maintaining the fuel evaporation section at a substantially constant temperature. The rate of burning is varied while maintaining the air-fuel ratio of the mixture substantially constant, because the rate of evaporation of the fuel is almost in proportion to the rate of supply of air to the fuel evaporation section. The heating means facilitates the evaporation of the fuel and permits a rapid rise and stabilization of burning after ignition.