Vernier CO2-BTA User Manual

CO2Gas Sensor

(Order Code CO2-BTA)

The Vernier CO2Gas Sen sor measures gaseous
carbon dioxide levels by monitoring the amount of
infrared radiation absorbed by carbon dioxide
molecules.

The sensor has two ranges: Low (0–10,000 ppm) and High (0–100,000 ppm).
Students can use the CO

2

Gas Sensor to measure the change in carbon dioxide

levels for a variety of systems, including

 A chamber containing small living things such as crickets, worms, or

germinating seeds

 A terrarium of plants undergoing respiration and photosynthesis cycles
 A cl assroom
 An enclosed atmosphere containing sodium hydroxide or potassium hydroxide

as CO

2

scavengers

 The chemical reaction between hydrochloric acid and sodium bicarbonate
 Carbon dioxide gas diffusing through a gas diffusion tube
 Fermentation or respiration of sugars
 Human respiration under various conditions (at rest vs. after exercise)

Note: Vernier products are designed for educational use. Our products are not
designed nor are they recommended for any industrial, medical, or commercial
process such as life support, patient diagnosis, control of a manufacturing
process, or industrial testing of any kind.

What's Included

 CO

2

Gas Sensor

 250 mL gas sampling bottle (Nalgene bottle with lid)

Compatible Software and Interfaces

See www.vern ier. com/ma nuals/c o2- bt a for a list of interfaces and software
compatible with the CO

2

Gas Sensor.

Getting S tarted

1. Connect the sensor to the interface (LabQuest Mini, LabQuest 2, etc.).

2. Start the appropriate data-collection software (Logger Pro, Logger Lite,
LabQuest App) if not already running, and choose New from File menu.

The software will identify the sensor and load a default data-collection setup.

If you are collecting data using a Chromebook™, mobile device such as iPad

®

or
Android™ tablet, or a Vernier wireless sensor or interface, please see the following
link for up-to-date connection information:

www.vern ier. com/s tart /co 2-b ta

Using the Product

1. Set the range switch on the sensor.

2. Connect the sensor following the steps in the Getting Started section of this
user manual.

The following includes additional important information about the
CO

2

Gas Sensor.

 Allow the CO

2

Gas Sensor to warm up for about 90 seconds before collecting

data. During warmup, the readings will be very low.

 The CO

2

Gas Sensor is sensitive to high humidity. Do not use it in a

condensing environment.

 Most experiments will use the Low range (0–10,000 ppm). The High range

would be appropriate when measuring human respiration as expired air is
typically 40,000–60,000 ppm CO

2

.

 The CO

2

Gas Sensor is somewhat sensitive to temperature changes. In most

cases, variations in CO

2

readings due to temperature changes are small
(<100 ppm on Low range, <1000 ppm on High range). The sensor is designed
to operate between 20 and 30°C. It can be used outside of this temperature
range; however, the readings will be less accurate, even if you calibrate the
sensor at the lower or higher temperature. With good experimental design, the
variation in CO

2

readings due to a temperature change will be negligible

compared to the overall change in CO

2

concentration. If an entire experiment
is to be conducted at a constant temperature, you could improve the accuracy
of the readings by calibrating the sensor at that temperature. This does not
prohibit taking readings using incubation temperatures or outdoor readings at
temperatures warmer or colder than the 20 to 30°C range. Allow enough time
for your CO

2

Gas Sensor to stabilize at the desired operating temperatures.

 The CO

2

Gas Sensor refreshes its reading every second, but typical changes in
experiments are so gradual that the recommended sampling rate is 4 seconds
per sample or slower. Gas must diffuse through the holes in the sensor tube
before the sensor detects any changes in concentration. Because diffusion of
gases is a slow process, there can be delays in the readings.

 To collect data in a controlled environment, it is recommended that you use

the 250 mL gas sampling bottle that is included with your sensor.

 To collect data simultaneously with the CO

2

Gas Sensor and O2Gas Sensor, it
is recommended that you purchase either the BioChamber 250 (250 mL
capacity) or the BioChamber 2000 (2 L capacity). Each BioChamber has a
second opening with a grommet so that you can insert two probes at once.

 Because the sensor operates on the basis of reading IR radiation, you should

avoid using the sensor in direct sunlight as much as possible. Even though the
IR detector is shielded, it is best to avoid the possibility of reflected light
affecting the readings by keeping the sensor in the shade when used outdoors.

 Best results are obtained when only one CO

2

Gas Sensor is connected to an

interfa ce at a t ime. Th e curren t draw from tw o o r more CO

2

Gas Sensors

connected to the same interface can cause erroneous data.

Videos

View videos related to this product at www.vern ier. com/c o2- bt a

2

Calibration

You should not have to perform a new calibration very often when using the
CO

2

Gas Sensor. A calibration is stored on the sensor before it is shipped. If you

do find that you need to calibrate your CO

2

Gas Sensor, it can be done using one

known CO

2

level. The calibration will be based on a sample of outside air having
a carbon dioxide concentration of about 400 ppm. Levels in your area may be
slightly higher due to localized influences such as automobile or industrial
emissions of carbon dioxide. Note: This calibration method is different from the
usual two-point calibration performed with other Vernier sensors. To calibrate the
CO

2

Gas Sensor:

1. Fill the gas sampling bottle (included with the sensor) to the brim with water,

take it outside, and dump the water to ensure it is filled with fresh air. While
still outdoors, insert the sensor into the gas sampling bottle containing fresh
outside air. You can now take the bottle and sensor to the location where the
calibration is to be done.

2. Connect the CO

2

Gas Sensor to the data-collection interface. Start the
data-collection software and identify your interface, if necessary. Let the sensor
warm up for at least 90 seconds.

3. When the CO

2

Gas Sensor has warmed up (readings should have stabilized),
use a paper clip to press down the calibration button. Release the button as
soon as the red light starts to blink. After about 30 seconds, the reading should
stabilize at a value of approximately 400 ppm (±100 ppm). If the reading is
significantly lower or higher than 400 ppm, simply press the button again to
repeat th e proce ss. Note: If the red light stays on solid, you have held the
button too long. In this case, wait for it to go off and press it again, releasing
as soon as it begins to flash.

3

Specifications

Measurement range of CO2Gas Sensor Low range: 0 to 10,000 ppm CO

2

High range: 0 to 100,000 ppm CO

2

Low range typical accuracy
(at stand ard pre ssure, 1 at m)

0 to 1,000 ppm ±100 ppm

1,000 to 10,000 ppm ±10% of reading

High range typical accuracy 0 to 1,000 ppm ±100 ppm

1,000 to 100,000 ppm ±20% of reading

Response time 95% of full-scale reading in

120 seconds

Warm-up time 90 seconds

Pressu re effe ct 0.19% of reading/mm of Hg from

standard pressure

Output signal range 0to4.0V

Input potential 5 V (±0.25 V)

Gas sampling mode diffusion

No rmal op erating te mperatu re ran ge 25°C (±5°C)

Operating humidity range 5 to 95% (non-condensing)

Storage temperature range –40 to 65°C

13-bit resolution 0 to 10,000 ppm CO2: 1.5 ppm

0 to 100,000 ppm CO

2

: 15 ppm

12-bit resolution 0 to 10,000 ppm CO2: 3 ppm

0 to 100,000 ppm CO

2

: 30 ppm

10-bit resolution 0 to 10,000 ppm CO2: 12 ppm

0 to 100,000 ppm CO

2

: 120 ppm

Care and Maintenance

Very important: Do not allow any liquids to come in contact with the CO2Gas
Sensor. The sensor is intended only for measuring gaseous, not aqueous, CO

2

concentration.

Temperatures greater than 65°C will damage the sensor.

It is recommended that you wash the gas sampling bottles by hand. Most
dishwashers will melt the plastic.

How the Sensor Works

The Vernier CO2Gas Sensor measures gaseous carbon dioxide levels in the range
of 0 to 10,000 ppm (Low range setting) or 0 to 100,000 ppm (High range setting)
by monitoring the amount of infrared radiation absorbed by carbon dioxide

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