The explosion limits of the mixture of combustible gas and air
The explosion limits of the mixture of combustible gas and air are related to the following factors: the type and chemical properties of the combustible gas; the purity of the combustible gas; the uniformity of the mixture of the combustible gas and air; the form, energy, and ignition position of the ignition source; the geometric shape and size of the explosion container; the temperature, pressure, and humidity of the mixture of the combustible gas and air.
Classification of gas detectors:
Classified by the detected object, there are combustible gas (including methane) detection and alarm instruments, toxic gas detection and alarm instruments, and oxygen detection and alarm instruments.
Classified by the detection principle, for the detection of combustible gases, there are catalytic combustion type, semiconductor type, thermal conductivity type, and infrared absorption type, etc.; for the detection of toxic gases, there are electrochemical type, semiconductor type, etc.; for the detection of oxygen, there is the electrochemical type, etc.
Classified by the usage method, there are portable and fixed types.
Classified by the usage place, there are conventional and explosion-proof types.
Classified by function, there are gas detectors, gas alarm instruments, and gas detection and alarm instruments.
Classified by the sampling method, there are diffusion type and pump-suction type.
Explosive environment and explosion-proof electrical equipment:
An environment containing an explosive mixture is called an explosive environment. Electrical equipment designed and manufactured according to specified conditions and that will not cause the explosion of the surrounding explosive mixture is called explosion-proof electrical equipment for explosive environments.
Explosion-proof marking:
The state has clear regulations on various explosion-proof types of explosion-proof electrical equipment for explosive environments. In "dIICT6", "d" indicates that the explosion-proof type is the flameproof type, "II" indicates electrical equipment for factory use, "C" indicates the strictest level of the maximum experimental safe gap or the minimum ignition current ratio (Level A, B, C) of the explosive gas mixture, and "T6" indicates the strictest level of the allowable maximum surface temperature (85°C).
Bus and branch line:
Bus and branch line refer to the connection methods between the controller and the detector. If each detector requires a wire to complete the communication with the controller, this connection method is called a branch line connection. If several detectors can share a wire to complete the communication with the controller, this connection method is called a bus connection.
