hanwei electronics MQ-4 www.hwsensor.com tel:86-371-67169080 fax: 86-371-67169090 e-mail: sales@hwsensor.com technical data MQ-4 gas sensor features * high sensitivity to ch 4 natural gas. * small sensitivity to alcohol, smoke. * fast response . * stable and long life * simple drive circuit application they are used in gas leakage detecting equipments in family and industry, are suitable for detecting of ch 4 ,natural gas.lng, avoid the noise of alcohol and cooking fumes and cigarette smoke. specifications a. standard work condition symbol parameter name technical condition remarks vc circuit voltage 5v 0.1 ac or dc v h heating voltage 5v 0.1 acor dc p l load resistance 20k r h heater resistance 33 ? 5% room tem p h heating consumption less than 750mw b. environment condition symbol parameter name technical condition remarks tao using tem -10 -50 tas storage tem -20 -70 r h related humidity less than 95%rh o 2 oxygen concentration 21%(standard condition)oxygen concentration can affect sensitivity minimum value is over 2% c. sensitivity characteristic symbol parameter name technical parameter ramark 2 rs sensing resistance 10k - 60k (1000ppm ch 4 ) (1000ppm/ 5000ppm ch 4 ) concentration slope rate 0.6 standard detecting condition temp: 20 2 vc:5v 0.1 humidity: 65% 5% vh: 5v 0.1 preheat time over 24 hour detecting concentration scope 200-10000ppm ch 4 , natural gas d. strucyure and configuration, basic measuring circuit parts materials 1 gas sensing layer sno 2 2 electrode au 3 electrode line pt 4 heater coil ni-cr alloy 5 tubular ceramic al 2 o 3 6 anti-explosion network stainless steel gauze (sus316 100-mesh) 7 clamp ring copper plating ni 8 resin base bakelite 9 tube pin copper plating ni a a fig. 1 configuration a configuration b fig.2
hanwei electronics MQ-4 www.hwsensor.com tel:86-371-67169080 fax: 86-371-67169090 e-mail: sales@hwsensor.com structure and configuration of MQ-4 gas sensor is shown as fig. 1 (configuration a or b), sensor composed by micro al 2 o 3 ceramic tube, tin dioxide (sno 2 ) sensitive layer, measuring electrode and heater are fixed into a crust made by plastic and stainless steel net. the heater provides necessary work conditions for work of sensitive components. the enveloped MQ-4 have 6 pin ,4 of them are used to fetch signals, and other 2 are used for providing heating current. electric parameter measurement circuit is shown as fig.2 e. sensitivity characteristic curve fig.2 sensitivity characteristics of the MQ-4 sensitvity adjustment resistance value of MQ-4 is difference to various kinds and various concentration gases. so,when using this components, sensitivity adjustment is very necessary. we recommend that you calibrate the detector for 5000ppm of ch 4 concentration in air and use value of load resistance ( r l ) about 20k (10k to 47k ). when accurately measuring, the proper alarm point for the gas detector should be determined after considering the temperature and humidity influence. fig.3 is shows the typical sensitivity characteristics of the MQ-4 for several gases. in their: temp: 20 humidity: 65% o 2 concentration 21% rl=20k ro: sensor resistance at 1000ppm of ch 4 in the clean air. rs:sensor resistance at various concentrations of gases. fig.4 is shows the typical depe ndence of the MQ-4 on temperature and humidity. ro: sensor resistance at 1000ppm of ch 4 in air at 33%rh and 20 degree. rs: sensor resistance at 1000ppm of ch 4 in air at different temperatures and humidities. fig.4 MQ-4 0.1 1 10 100 1000 10000 ppm r s / r o lpg ch4 h2 co alcohol smoke air MQ-4 0.5 0.6 0.7 0.8 0.9 1 1.1 1.2 1.3 1.4 -10 0 10 20 30 40 50 temp r s / r o 33%rh 85%rh
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