PASCO PS-2194 User manual

Ethanol Sensor (PS-2194)
Included Parts
Amplifier
Probe
PTFE (Teflon Plumber’s) tape for membrane
replacement (not pictured)
Additional Parts Required
•PASPORT-compatible interface
•PASCO Data Collection Software
Replacement Parts
•See Technical Support
Quick Start
1. Connect the amplifier to your PASPORT-compatible
interface.
2. Connect the probe to the amplifier.
3. If you are using a computer, connect the PASPORT
interface to it and start the PASCO Data Collection
Software.
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
containing less than 3% ethanol.
6. Begin recording data in the software.
The probe stabilizes after about 10 minutes of warm-up time.
Introduction
The Ethanol Sensor measures the concentration of ethanol in a
gas or indirectly in a liquid. The sensor’s probe contains a
material 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
•Do not expose the probe to gas containing more than 3%
ethanol, including the gas above alcoholic beverages.
Higher ethanol concentrations will deplete the sensing
element. Note that the gas above a liquid contains about
the same concentration of ethanol as the liquid itself.
•Ensure that the teflon tape 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, wipe it gently with a soft cloth or
lightly damp paper towel and dry it quickly. Note that the
probe may be degraded or destroyed.
•Do not immerse the probe. The membrane (if it is in good
condition) will protect the probe in case of accidental
immersion. 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-compatible interface.
2. Connect the probe to the amplifier.
Figure 1. Connecting the probe and interface
3. If you are using a computer, connect the PASPORT-
compatible interface to it and start the PASCO Data
Collection Software.
Warm-up
The probe contains a heating element. After connecting the
sensor to a powered PASPORT-compatible interface, wait about
10 minutes for the sensor’s temperature to stabilize. Students
should start the sensor before setting up the lab to ensure that
its temperature has stabilized in time for data collection.
If the temperature of the gas surrounding the probe changes, the
probe will need some time to stabilize again.
The sensitivity of the probe changes with temperature. Make
measurements 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 discoloration.
2. Place the end of the probe just above a solution, or in a
gas, containing less than 3% ethanol.
3. Start data recording.
NOTE: For more information on data collection
using PASCO software, see the PASCO
Capstone or SPARKvue online help.
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Calibration
For accurate measurements, first calibrate the sensor. You will
need a solution of 1% ethanol in water; to prepare this solution,
pipette in 1.43 mL (or 1.24 g) of 70% ethanol in a 100 mL
volumetric flask and fill to the line with 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 the software.
4. Wait until the reading stabilizes.
5. Press and hold the 1% CAL button on the sensor for 4
seconds.
Immediately after a successful calibration, the sensor’s output
will read 1%, and the button will be 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,
typically used by plumbers. The membrane protects the sensing
element from liquid, but is permeable to ethanol gas.
Membrane Replacement
Change the membrane when it is torn or discolored.
1. Pull the retaining ring off the end of the probe.
2. Remove 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 probe.
5. Push the retaining ring onto the end of the probe over the
new membrane.
6. Optional: Use a sharp knife to trim off excess membrane
from around the retaining ring.
Retaining ring
Old membrane
New membrane
Excess membrane
Factors that Affect the Measurement
Temperature and humidity: The sensor’s temperature is
determined both by 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 calibration and measurement.
Air flow: Air flow around or into the probe affects its
temperature. Minimize air flow during calibration and
measurement.
Interference molecules: In addition to ethanol gas, the sensor
responds to hydrogen, isobutane, carbon monoxide, and
methane.
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
solution 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. This data illustrates the importance of
keeping the temperature constant during calibration and
measurement.
Figure 2. Sensor response vs. temperature; the actual ethanol
concentration is constant
The relationship between temperature and sensor response
varies from probe to probe. To create a similar plot for your
specific probe, follow the steps below.
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
temperature 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.
Ethanol Sensor | PS-2194
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Software Help
See the SPARKvue Help or PASCO Capstone Help for
information about collecting, displaying, and analyzing data.
•In SPARKvue, select the HELP button ( ) in any screen,
including the Home Screen.
•In PASCO Capstone, select PASCO Capstone Help from
the Help Menu, or press F1.
Sample Experiment
1. Mix approximately half a teaspoon of baker’s yeast and one
teaspoon of a simple sugar (such as glucose or lactose)
into 100 mL of lukewarm (about 42°C) water.
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
concentration increases.
Repeat these steps at different temperatures, and with different
amounts and types of sugar and yeast. Note how these factors
affect the rate of ethanol formation.
Specifications and accessories
Visit the product page at pasco.com/product/PS-2194 to view
the specifications and explore accessories. You can also
download experiment files and support documents from the
product page.
Experiment files
Download one of several student-ready activities from the
PASCO Experiment Library. Experiments include editable
student handouts and teacher notes. Visit
pasco.com/freelabs/PS-2194.
Technical Support
Need more help? Our knowledgeable and friendly Technical
Support staff is ready to answer your questions or walk you
through any issues.
Chat pasco.com
Phone [phone] x1004 (USA)
[phone] (outside USA)
Email [e-mail]
Replacement Parts
Replacement parts may be available for this product. Contact
Technical Support about replacement parts.
•Replacement probe (contact Tech Support)
•Additional PTFE tape (contact Tech Support)
For more information about the Ethanol Sensor, and the latest
revision of this Instruction Sheet, visit the PASCO website at
www.pasco.com/manuals and enter the product name or product
number (PS-2194) in the Search text window.
Limited Warranty
For a description of the product warranty, see the Warranty and Returns page at
www.pasco.com/legal.
Copyright
This document is copyrighted with all rights reserved. Permission 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 scientific, is prohibited.
Trademarks
PASCO and PASCO scientific are trademarks or registered trademarks of PASCO
scientific, in the United States and 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.
Product end-of-life disposal
This electronic product is subject to disposal and recycling regulations
that vary by country and region.
It is your responsibility to recycle your electronic equipment per your
local environmental laws and regulations to ensure that it will be
recycled in a manner that protects human health and the environment.
To find out where you can drop off your waste equipment for recycling, please
contact your local waste recycle or disposal service, or the place where you
purchased the product.
The European Union WEEE (Waste Electronic and Electrical Equipment) symbol
on the product or its packaging indicates that this product must not be disposed of
in a standard waste container.
CE statement
This device has been tested and found to comply with the essential requirements
and other relevant provisions of the applicable EU Directives.
FCC statement
This device complies with part 15 of the FCC Rules.
Operation is subject to the following two conditions:
(1) This device may not cause harmful interference, and (2) this device must accept
any interference received, including interference that may cause undesired
operation.
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