FIGARO PRODUCT INFORMATION TGS 826 - for the Detection of Ammonia Features: Applications: * Ammonia leak detection in refrigerators * Ventilation control for the agricultural and poultry industries * High sensitivity to ammonia * Quick response to low concentrations of ammonia * Uses simple electrical circuit * Ceramic base resistant to severe environment The sensing element of TGS826 is a metal oxide semiconductor which has low conductivity in clean air. In the presence of a detectable gas, the sensor's conductivity increases depending on the gas concentration in the air. A simple electrical circuit can convert the change in conductivity to an output signal which corresponds to the gas concentration. The TGS826 has high sensitivity to ammonia gas. The sensor can detect concentrations as low as 30ppm in the air and is ideally suited to critical safety-related applications such as the detection of ammonia leaks in refrigeration systems and ammonia detection in the agricultural field. 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 at 50ppm of ammonia 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 50ppm of ammonia at various temperatures/humidities Ro = Sensor resistance at 50ppm of ammonia at 20C and 65% R.H. Sensitivity Characteristics: Temperature/Humidity Dependency: 10 10.0 Iso-butane Hydrogen 1 0% Rs/Ro Rs/Ro Air 20% 40% 65% 100% 1.0 RH% Ammonia Ethanol 0.1 10 100 Concentration (ppm) 1000 0.1 -30 -20 -10 0 10 20 30 40 50 Ambient Temperature (C) 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. Structure and Dimensions: 19.5 0.5 1.0 0.05 1 11.0 0.2 2 45 3.0 0.2 5 4 6.5 0.2 23.0 1.0 45 6 3 9.5 0.3 13.5 1 Sensing Element: Metal oxide is sintered to form a thick film on the surface of an alumina ceramic tube which contains an internal heater. 2 Sensor Base: Alumina ceramic 3 Flame Arrestor: 100 mesh SUS 316 double gauze + 0.3 - 0.2 Pin Connection and Basic Measuring Circuit: The numbers shown around the sensor symbol in the circuit diagram at the right correspond with the pin numbers shown in the sensor's structure drawing (above). Since the sensor has a polarity, DC voltage is always required for circuit voltage (a white dot indicates pin 2). When the sensor is connected as shown in the basic circuit, output across the Load Resistor (VRL) increases as the sensor's resistance (Rs) decreases, depending on gas concentration. Basic Measuring Circuit: Specifications: Model number TGS 826 Target gases Ammonia Typical detection range 30 ~ 300 ppm Standard circuit conditions Electrical characteristics under standard test conditions VH Circuit voltage VC Load resistance RL Heater resistance RH 303 at room temp. 167mA Heater current IH Heater power consumption PH Sensor resistance Rs Sensitivity (change ratio of Rs) Test gas conditions Standard test conditions 5.00.2V DC/AC Heater Voltage Max. 24V Ps 15mW (DC only) Ps 15mW Variable 833mW Pin #2 is indicated by a white dot on the sensor's base. VH = 5.0V DC 20~100k in 50ppm ammonia 0.55 0.15 Rs (150ppm) Rs (50ppm) Ammonia in air at 202C, 655%RH Circuit conditions Conditioning period before test VC = 5.00.01V DC VH = 5.00.05V DC RL = 33k1% 7 days Sensor Resistance (Rs) is calculated by the following formula: VC Rs = ( -1) x RL VRL Power dissipation across sensor electrodes (Ps) is calculated by the following formula: Ps = FIGARO ENGINEERING INC. 1-5-11 Senba-nishi Mino, Osaka 562-8505 JAPAN Phone: (81)-72-728-2561 Fax: (81)-72-728-0467 email: figaro@figaro.co.jp REV: 05/04 VC2 x Rs (Rs + RL)2 Special Note: A more narrowly defined range of Rs or Rs/Ro will be indicated on each production lot (see Appendix). Preselected ranges of Rs or Rs/Ro are not available.