PRODUCT INFORMATION TGS 2442 - for the detection of Carbon Monoxide Features: Applications: * Low power consumption * High sensitivity/selectivity to carbon monoxide (CO) * Miniature size * Low sensitivity to alcohol vapor * Long life and low cost * Low humidity dependency * CO detectors * Air quality controllers * Indoor parking lot ventilation TGS 2442 utilizes a multilayer sensor structure. A glass layer for thermal insulation is printed between a ruthenium oxide (RuO2) heater and an alumina substrate. A pair of Au electrodes for the heater are formed on a thermal insulator. The gas sensing layer, which is formed of tin dioxide (SnO2), is printed on an electrical insulation layer which covers the heater. A pair of Au electrodes for measuring sensor resistance are formed on the electrical insulator. Activated charcoal is filled between the internal cover and the outer cover for the purpose of reducing the influence of noise gases. TGS 2442 displays good selectivity to carbon monoxide, making it ideal for CO monitors. In the presence of CO, the sensor's conductivity increases depending on the gas concentration in the air. A simple pulsed electrical circuit operating on a one second circuit voltage cycle can convert the change in conductivity to an output signal which corresponds to gas concentration. The figure below represents typical sensitivity characteristics, all data having been gathered at standard test conditions (see reverse side of this sheet). The Y-axis is indicated as sensor resistance ratio (Rs/Ro) which is defined as follows: Rs = Sensor resistance of displayed gases at various concentrations Ro = Sensor resistance in 100ppm CO The figure below represents typical temperature and humidity dependency characteristics. Again, the Y-axis is indicated as sensor resistance ratio (Rs/Ro), defined as follows: Rs = Sensor resistance at 30ppm, 100ppm and 300ppm of CO at various temperatures and 50%R.H. Ro = Sensor resistance at 300ppm of CO at 25C and 50% R.H. Sensitivity Characteristics: 100 Air Temperature/Humidity Dependency: 1000 Ethanol 10 50%RH 100 H2 Rs/Ro 1 Air Rs/Ro10 CO 30ppm 0.1 0.01 1 CO 1 10 100 1000 Gas Concentration (ppm) 10000 0.1 CO 100ppm CO 300ppm -20 -10 0 10 20 30 Temperature (C) 40 50 60 IMPORTANT NOTE: OPERATING CONDITIONS IN WHICH FIGARO SENSORS ARE USED WILL VARY WITH EACH CUSTOMER'S SPECIFIC APPLICATIONS. FIGARO STRONGLY RECOMMENDS CONSULTING OUR TECHNICAL STAFF BEFORE DEPLOYING FIGARO SENSORS IN YOUR APPLICATION AND, IN PARTICULAR, WHEN CUSTOMER'S TARGET GASES ARE NOT LISTED HEREIN. FIGARO CANNOT ASSUME ANY RESPONSIBILITY FOR ANY USE OF ITS SENSORS IN A PRODUCT OR APPLICATION FOR WHICH SENSOR HAS NOT BEEN SPECIFICALLY TESTED BY FIGARO. Basic Measuring Circuit: Circuit voltage (VC) is applied across the sensing element which has a resistance (Rs) between the sensor's two electrodes (pins No. 2 and No. 3) and a load resistor (RL) connected in series. The sensing element is heated by the heater which is connected to pins No. 1 and No. 4. Heating cycle--The sensor requires application of a 1 second heating cycle which is used in connection with a circuit voltage cycle of 1 second. Each VH cycle is comprised by 4.8V being applied to the heater for the first 14ms, followed by 0V pulse for the remaining 986ms. The Vc cycle consists of 0V applied for 995ms, followed by 5.0V for 5ms. For achieving optimal sensing characteristics, the sensor's signal should be measured after the midpoint of the 5ms Vc pulse of 5.0V (for reference, see timing chart below). NOTE: Application of a Vc pulse condition is required to prevent possible migration of heater materials into the sensing element material. Under extreme conditions of high humidity and temperature, a constant Vc condition could result in such migration and cause long term drift of Rs to higher values. A 5ms Vc pulse results in significantly less driving force for migration than a constant Vc condition, rendering the possibility of migration negligibly small. Structure and Dimensions: unit: mm Top View Specifications: 9.20.2 Model number TGS 2442 Sensing element type M1 Standard package TO-5 metal can Target gases Carbon monoxide Typical detection range 30 ~ 1000 ppm Standard circuit conditions Electrical characteristics under standard test conditions Heater voltage cycle VH VHH=4.8V0.2V DC, 14ms VHL=0.0, 986ms Circuit voltage cycle VC VC=0V for 995ms, VC=5.0V0.2V DC for 5ms Load resistance RL variable (10k) Heater resistance RH 17 2.5 at room temp. Heater current IH approx. 203mA(in case of VHH) Heater power consumption PH approx. 14mW (ave.) Sensor resistance Rs 13.3k ~ 133k in 100ppm of carbon monoxide Sensitivity (change ratio of Rs) 0.13 ~ 0.31 Test gas conditions Standard test conditions Circuit conditions Conditioning period before test 8.10.2 0.3 0.3 7.250.4 12.70.5 0.2 6.0+0,-0.3 Side View 1.50.1 10.01.0 0.550.05 45o 4 1 5.10.1 Carbon monoxide in air at 202C, 655%RH Same as Std. Circuit Condition (above) 2 days or more Bottom View 3 2 unit;mm Sensor resistance (Rs) is calculated with a measured value of Vout as follows: Rs = Vcx RL Vout - RL The value of sensitivity () is calculated with two measured values of Rs as follows: = Rs (CO,300ppm) Rs (CO,100ppm) For information on warranty, please refer to Standard Terms and Conditions of Sale of Figaro USA Inc. REV: 07/07 FIGARO USA INC. 121 S. Wilke Rd. Suite 300 Arlington Heights, IL 60005 Tel: 847-832-1701 Fax: 847-832-1705 email: figarousa@figarosensor.com