Explanation of commonly used terms for gas detectors
Explosion-proof marking countries have clear regulations on various explosion-proof types of explosion-proof electrical equipment for explosive environments.
d In IICT6, d indicates that the explosion-proof type is explosion-proof.
II represents factory electrical equipment, C represents the most stringent level of the maximum test clearance or minimum ignition current ratio (A, B, C three levels) of explosive gas mixtures, and T6 represents the most stringent level of the maximum allowable surface temperature ( 85℃)
Explosive environment and explosion-proof electrical equipment The environment containing explosive mixtures is called an explosive environment. Electrical equipment designed and manufactured according to specified conditions without causing the explosion of surrounding explosive mixtures becomes explosion-proof electrical equipment for explosive environments.
Properties related to common flammable gases Gas name Molecular formula Specific gravity (air = 1) TLV-TWA (PPM) TLV-STEL (PPM) TLV-IDLH (PPM) LEL (V%) HEL (V%)
Hydrogen H2 0.0695 4 75
Ammonia NH3 0.58 25 35 500 15 28
Carbon monoxide C0 0.976 25 1500 12.5 74
Hydrogen sulfide H2S 1.115 4.3 45
Chlorine CL2 0.5 1 30
Methane CH4 0.554 5 15
Ethane C2H6 1.035 3 12.5
Ethylene C2H5 0.975 2.7 36
Propane C3H8 1.56 2 9.5
Propylene C3H6 1.49 2.4 10.3
Butane C3H6 2.01 800 1.9 8.5
Butene-1 C4H8 1.937 1.6 10
Butene-2 C4H8 1.94 1.8 9.7
Butadiene C4H6 1.87 2 20000 2 12
Isobutane (CH3)3CH 2.068 1.8 8.4
Sensor preheating: After the sensor is powered on, the output value is unstable. The period of waiting for the output value to stabilize becomes sensor preheating.
Sensor Poisoning When the sensor is powered on, if it comes into contact with a gas whose concentration is far beyond its range, it may cause the sensor's output value to remain at a high level. Some poisoned sensors can be recovered after a period of time, and some cannot.
