PASCO PS-2126A User Manual
®
Oxygen Gas Sensor
sensor amplifier
sampling
bottle
connecting cable
sensing
element
rubber stopper
Included Equipment Part Number
Sensor Amplifier
PS-2126A (includes
sensing element)
Oxygen Sensing Element (with deflector)
699-299
Rubber Stopper
699-08186
Connecting Cable (3.5 millimeter)
514-08583
Sampling Bottle
650-064
Required Equipment
PASPORT Interface
See PASCO catalog
or www.pasco.com
PS-2126A
Oxygen Sensing Element Life:
Galvanic fuel cells have a limited lifetime which is determined
by their age and their exposure to oxygen. This is similar to
the life of a battery in a flashlight. If the flashlight frequently
used, the battery life will not be as long as it would have been
with limited usage. Similarly, the fuel cell’s useful life is
determined by its exposure to oxygen gas.
The fuel cell included with the PS-2126A has a useful life of
900,000 oxygen percent (O
An example: If the sensor is used in a 100% oxygen atmosphere, the life of the sensor may be calculated as
900,000 O
9,000 hours. This is about 1 year.
% hours divided by 100% oxygen which is
2
Instruction Sheet
*012-11736*
%) hours.
2
012-11736B
Introduction
The PS-2126A Oxygen Gas Sensor measures oxygen gas concentration in percent (%) and parts per million (ppm) oxygen.
It can be used to study plant, animal, or cellular respiration; air
quality; and the rate of oxygen (O
reactions (see the experiment on page 2 for one example).
How it works:
The Oxygen Sensing Element is a galvanic fuel cell with a gas
permeable membrane at one end. It is very similar to a battery .
The fuel cell contains an electrolyte, anode and cathode. When
oxygen enters the fuel cell through the membrane, a chemical
reaction between the metallic cathode and anode and the electrolyte occurs. This chemical reaction produces a voltage and
current that is present at the output jack at the other end of the
Oxygen Sensing Element. The current produced is proportional to the concentration of oxygen present.
) production in chemical
2
The life of the sensor in normal air (20.9% oxygen) is
900,000 O
% hours divided by 20.9% oxygen which is
2
43,062 hours. This is about 4.9 years.
The sensor is guaranteed for a minimum of 2 years from the
date of manufacture. This is the absolute guarantee. If it is
used in a 100% oxygen atmosphere its life will be shortened.
If it is used in normal air, its life will be 4 to 5 years. There is
reported evidence of this particular sensing element being in
use for almost 10 years. In the end, the useful life of the sensing element is dependent on the manner in which it is used.
Setup
Connect the Oxygen Gas Sensor to your PASPORT interface.
To prepare the Oxygen Sensing Element for use:
1. Remove the Oxygen Sensing Element and deflector from
the packaging.
2. Remove the pink tape from the Oxygen Sensing Element.
3. Carefully thread the deflector onto the Oxygen Sensing
Element.
4. Slide the rubber stopper over the deflector.
®
Model No. PS-2126A Collecting O2 Samples
5. Plug one end of the connecting cable into the Oxygen
Sensing Element.
6. Plug the other end of the connecting cable into the Sensor
Amplifier.
7. Connect the Sensor Amplifier to the PASCO interface.
8. Refer to the documentation that came with the PASCO
interface and software for further instructions for data
collection.
Collecting O2 Samples
To collect an atmospheric sample, hold the bottle upright and
open to the air. Insert the end of the sensing element into the
bottle. Press the rubber stopper into the neck to seal the bottle.
To collect expired air or
other gas samples, place the
sensing element inside a
plastic bag. Press any atmospheric air out of the bag.
Use a tube to fill the bag
with the gas sample. Hold,
tie, or clamp the bag closed
round the tube and sensing
element cable to contain the
gas sample and exclude atmospheric air.
Calibration
The sensor is factory calibrated. However, for greater accuracy, you can follow these steps to calibrate the sensor:
1. With the sensor connected to a powered PASPORT inter-
face, place the sensing element in the empty sampling
bottle. Outside air has an O
2. Press the CAL (20.9%) button on the sensor and hold it
for 3 seconds. The green light will flash on and off for 4
seconds, indicating that calibration is in progress.
3. After 4 seconds, the reading will stabilize at 20.9%. When
calibration is complete, the light will stop flashing.
Note: If the green light flashes rapidly after calibration, the sensing element may be expired and it may need replacement.
concentration 20.9%.
2
Experiment: Oxygen
Production from Liver Catalase
Equipment required: Oxygen Gas Sensor with sampling bottle, beef
or chicken liver, hydrogen peroxide, pipette, mortar and pestle, ice
bath, boiling water, and safety goggles.
Safety: Always wear safety goggles when performing this experiment.
Do not allow excessive pressure to develop in the sampling bottle.
1. Place the liver in an open container and allow it to warm
to room temperature.
When doing an experiment that requires a faster than usual
response time, the response time of the sensor may be
increased by removing the white deflector and stopper from
the Oxygen Sensing Element. This shortens the path to the
sensor's membrane allowing it to be populated more rapidly
with the sample.
The purpose of the white deflector is to deflect air from an air
stream into the sensing element and provide protection for the
gas permeable membrane. It also holds the rubber stopper.
While the white deflector is removed from the sensing element, be careful not to place sharp objects near the membrane
as puncturing the membrane could lead to damage to the sensing element and electrolyte leaking from the membrane.
Removal of the deflector is not required or recommended during typical operating conditions.
Warning: Do not allow the sensing element to contact liquids.
2. (Optional) Calibrate the Oxygen Gas Sensor (see above).
3. Grind the liver to a mushy consistency.
4. Place 10 mL of hydrogen peroxide into the clean, dry
sampling bottle.
Note: Perform step 5 through 7 carefully and quickly.
5. With a pipette, extract 1 mL of blood/homogenate from
the ground liver and release it into the sampling bottle.
6. Insert the end of the sensing element into the bottle. Press
the rubber stopper into the neck of the bottle just enough
to close the bottle, but not too tightly
7. Start data collection on the computer or interface.
8. After about 300 seconds, stop data collection.
9. Clean and dry the sampling bottle. Repeat steps 4 through
8 with cold liver homogenate that has been chilled in an
ice bath. Repeat again with liver homogenate that has
been boiled in water.
10. Compare your results from the three runs.
2
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