PASCO Specialty & Mfg. PS-2194 User's Manual
Contents
1. Instruction Sheet 012 10287B Ethanol Sensor PS 2194 Included Parts 1 Amplifier 2 Probe 3 PTFE tape for membrane replacement not pictured Additional Part Required e PASPORT interface or datalogger Related Parts e Replacement probe PASCO part 0033 10338 e Additional PTFE tape 720 062 Quick Start 1 Connect the amplifier to your PASPORT interface 2 Connect the probe to the amplifier 3 Ifyou are using a computer connect the PASPORT interface to it and start DataStudio 4 Ensure that the membrane is installed and intact There should be no tears or discoloration 5 Place the end of the probe in the gas above a solution con taining less than 3 ethanol 6 Press or click the start button to begin recording data The probe stabilizes after about 10 minutes of warm up time Py Ryee Introduction The Ethanol Sensor measures the concentration of ethanol in a gas or indirectly in a liquid The sensor s probe contains a mate rial whose resistance decreases in the presence of ethanol The sensor translates this resistance into an ethanol concentration measurement which is recorded and displayed by the connected computer or datalogger The Ethanol Sensor is well suited for continuous recording and discrete measurements Precautions e Do not expose the probe to gas containing more than 3 ethanol including the gas above alcoholic beverages Higher ethanol concentrations will deplete the2. The relationship between temperature and sensor response varies from probe to probe To create a similar plot for your specific probe follow these steps 1 Place the probe and a temperature sensor just above a 1 ethanol solution Keep the temperature sensor about 1 cm away from the heating element at the end of the ethanol probe Seal the container to keep the gas in 2 Calibrate the ethanol sensor at room temperature 3 Place the container in a cold water bath Wait for the temper ature inside the container to equilibrate with the water bath 4 Start data recording 5 Use a hot plate to slowly increase the temperature of the water bath 0 5 0 0 5 10 15 20 25 30 35 40 45 Temperature C Sensor response vs temperature the actual ethanol concentration is constant PASC Ce PS 2194 Sample Experiment 1 Place a mixture of luke warm water about 42 C sugar and baker s yeast in a container 2 Place the end of the probe just above the liquid 3 Start data recording 4 Observe the reading for about 45 minutes as the ethanol con centration increases IMPORTANT Remove the probe from the gas before the concentration exceeds 3 Repeat these steps at different temperatures and with different amounts and types of yeast and sugar Note how these factors affect the rate of ethanol formation Specifications Accuracy 20 of reading Range 0 to 3 ethanol in gas Technical Suppor
3. probe 5 Push the retaining ring onto the end of the probe over the membrane 6 Optionally use a sharp knife to trim off excess membrane from around the retaining ring retaining ring L a old membrane new membrane excess membrane Membrane replacement Factors that Affect the Measurement Temperature and humidity The sensor s temperature is determined by both its internal heater and the temperature of its surroundings Allow the probe time to reach a stable temperature after you plug it in or after the temperature of its surroundings changes Keep temperature and humidity constant during calibra tion and measurement Air flow Air flow around or into the probe affects its tempera ture Minimize airflow during calibration and measurement Other gases In addition to ethanol gas the sensor responds to hydrogen isobutane carbon monoxide and methane TEIH Ethanol Sensor Sensor Response versus Temperature The graph below shows how changing temperature affects the sensor The probe was placed in the gas above a 1 ethanol solu tion and calibrated The temperature was then varied between 5 C and 45 C Though the actual ethanol concentration of the solution remained constant the sensor s reading deviated from 1 at temperatures above and below the calibration temperature These data illustrate the importance of keeping the temperature constant during calibration and measurement
4. sensing ele ment Note that the gas above a liquid contains about the same concentration of ethanol as the liquid itself e Ensure that the membrane is installed and intact before using the probe The membrane prevents the sensing element from getting wet If the sensing element accidentally gets wet rinse and dry it quickly Note that the probe may be degraded or destroyed e Do not immerse the probe The membrane if it is in good condition will protect the probe in case of accidental immer sion However the probe is designed for use in gas only Connecting the Parts 1 Plug the amplifier s PASPORT connector into any port of a PASPORT interface or datalogger 2 Connect the probe to the amplifier to PASPORT interface Connecting the probe and interface 3 Ifyou are using a computer connect the PASPORT interface to it and start DataStudio 800 772 8700 Www pasco com Ethanol Sensor Warm up The probe contains a heating element After connecting the sen sor to a powered PASPORT interface wait about 10 minutes for the sensor s temperature to stabilize If the temperature of the gas surrounding the probe changes the probe will need some time to stabilize again The sensitivity of probe changes with temperature Make mea surements at a constant temperature after the probe temperature has stabilized Collecting Data 1 Ensure that the membrane is installed and intact There should be no tears or
5. discoloration 2 Place the end of the probe just above a solution or in a gas containing less than 3 ethanol 3 Press or click the start button to begin recording data Calibration For accurate measurements first calibrate the sensor You will need a solution of 1 ethanol in water The solution should be at the same temperature as the solutions to be measured Calibration data is stored in the sensor s memory and persists until the sensor is calibrated again even if the sensor is unplugged from the interface 1 Connect the sensor to an interface as described above 2 Place the probe above the 1 ethanol solution 3 Observe the ethanol concentration reading in software or on the datalogger 4 Wait until the reading stabilizes 5 Press and hold the 1 CAL button on the sensor for 4 s Immediately after a successful calibration the sensor s output reads 1 and the button is illuminated About the Membrane A roll of membrane material is included with the sensor The material is PTFE thread sealing tape about 25 mm wide typi cally used by plumbers The membrane protects the sensing ele ment from liquid but is permeable to ethanol gas PS 2194 Membrane Replacement Change the membrane when it is torn or discolored 1 Pull the retaining ring off the end of the probe 2 Remove the and discard the old membrane 3 Cut a 25 mm square of new membrane material 4 Place the new membrane over the end of the
6. t For assistance with any PASCO product contact PASCO at Address PASCO scientific 10101 Foothills Blvd Roseville CA 95747 7100 Phone 916 786 3800 worldwide 800 772 8700 U S Fax 916 786 7565 Web WWw pasco com Email support pasco com For more information about the Ethanol Sensor and the latest revision of this Instruction Sheet visit www pasco com go PS 2194 Limited Warranty For a description of the product warranty see the PASCO catalog Copyright The PASCO scientific 012 10287B Etha nol Sensor Instruction Sheet is copyrighted with all rights reserved Per mission is granted to non profit educational institutions for reproduction of any part of this manual providing the reproductions are used only in their laboratories and classrooms and are not sold for profit Reproduction under any other circumstances without the written consent of PASCO sci entific is prohibited Trademarks PASCO PASCO scientific and PASPORT are trademarks or registered trademarks of PASCO scientific in the United States and or in other countries All other brands products or service names are or may be trademarks or service marks of and are used to identify products or services of their respective owners For more information visit www pasco com legal
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