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TEMPERATURE SENSOR 0511 -20 .. 125 °C USER’S GUIDE Figure 1 The Temperature Sensor 0511 CENTRE FOR MICROCOMPUTER APPLICATIONS http://www.cma-science.nl Description The Temperature sensor 0511 measures temperature and temperature differences in the range of -20C to 125C. This sensor uses the 20 k NTC thermistor (thermal resistor), which is positioned in a stainless steel tube. The thermistor is a variable resistor whose resistance decreases nonlinearly with increasing temperature. The best-fit approximation of this non-linear characteristic is the so-called Steinhart-Hart equation. A lab interface measures the resistance value, R, at a particular temperature, and converts the resistance using the Steinhart-Hart equation: T = [K0 + K1(ln 1000R) + K2(ln 1000R)3]-1 - 273.15 where T the temperature in C, and R the measured resistance in k K0 = 1.02119 x 10-3, K1 = 2.22468 x 10-4 and K2 = 1.33342 x 10-7. The sensor has a built-in facility for automatic sensor identification (Auto-id sensor). Examples of experiments The temperature sensor is a general-purpose laboratory sensor. It is designed to be used as you would use thermometer for experiments in chemistry, physics, and biology. Examples of applications are: - Measuring freezing and boiling points. - Monitoring endothermic and exothermic reactions. - Specific heat experiments. Sensor Chemical Tolerance The temperature sensor body is constructed from grade 316 stainless steel. This high-grade stainless steel provides a high level of corrosion resistance for use in the science classroom. Here are some general guidelines for usage: 1. The probe handle is constructed of molded plasticized Santoprene™ . While this material is very chemical resistant, we recommend that you avoid submerging the probe beyond the stainless steel portion. 2. Always wash the probe thoroughly after use. 3. The probe can be left continuously in water at temperatures within the range of – 25° to 150°C. Continuous usage in saltwater will cause only minor discoloration of the probe, with no negative effect on performance. 4. You can leave the probe continuously in most organic compounds, such as methanol, ethanol, 1-propanol, 2-propanol, 1-butanol, n-hexane, lauric acid, paradichlorobenzene, phenyl salicylate, and benzoic acid. The probe should not be left in n-pentane for more than 1 hour. 5. The probe can be left in strong basic solutions, such as NaOH, for times up to 48 hours, with only minor discoloration. We do not recommend usage in basic solutions that are greater than 3 M in concentration. 6. The Table 1 provides the maximum length of time we recommend for probe exposure to some common acids. Probes left in an acid longer than these times may bubble and/or discolor, but will still be functional. We do not recommend 2 probes be left to soak in any acid longer than 48 hours. Acid 1 M HCL 2 M HCL 3 M HCL 1 M H2SO42 M H2SO4 3 M H2SO4 1 M HNO3 2 M HNO3 3 M HNO3 1 M CH3COOH 2 M CH3COOH 3 M CH3COOH 1 M H3PO4 2 M H3PO4 3 M H3PO4 Maximum Exposure Time 20 minutes 10 minutes 5 minutes 48 hours 20 minutes 10 minutes 48 hours 48 hours 48 hours 48 hours 48 hours 48 hours 48 hours 48 hours 48 hours Table 1. Maximum acid exposure time. Calibration The output of the temperature sensor is non-linear with respect to temperature. Simple use the calibration supplied in the standard sensor library of the Coach program. The name of the Temperature sensor in the standard sensor library of the Coach program is Temperature sensor (0511bt) (CMA) (-25..150°C). Figure 2. Default calibration graph of the Temperature sensor used in the standard Coach sensor library. 3 Technical data Temperature range -20 C to 125 C Principle, calibration type 20 k NTC Thermistor; non-linear Calibration curve (Steinhart-Hart equation) T = [K0 + K1(ln 1000R) + K2(ln 1000R)3]-1 Where T the temperature in C, and R the measured resistance in k K0 = 1.02119E-03; K1 = 2.22468E-04; K2 = 1.33342E-07 Coefficients Maximum temperature that sensor can tolerate without damage 150 C Resolution using 12 bit 5 V A/D converter 0.08 C (-25 to 0C) 0.03 C (0 to 40C) 0.1 C (40 to 100C) 0.25 C (100 to 125C) Accuracy 0.2 C at 0 C and 0.5 C at 100 C Maximum current drain 0.5 mA Response time 95% of full reading: 11 s 98% of full reading: 18 s 100% of full reading: 30 s Probe dimensions Probe length (handle plus body): 16 cm Stainless steel body: length 11 cm, diameter 4 mm Probe handle: length 5 cm, diameter 1.25 cm Connection Right-hand BT (British Telecom) connector Warranty: The 0511 Temperature sensor is warranted to be free from defects in materials and workmanship for a period of 12 months from the date of purchase provided that it has been used under normal laboratory conditions. This warranty does not apply if the sensor has been damaged by accident or misuse. Note: This product is to be used for educational purposes only. It is not appropriate for industrial, medical, research, or commercial applications. Rev. 11/5/12 4