Instructions
3
lifespan. If possible, store the device in an area that is not exposed to
temperature extremes.
Note: It is recommended that you wash the Nalgene bottle by hand. Most
dishwashers will melt plastic bottles.
Water Resistance
Important: Go Direct CO
2
Gas is neither waterproof, nor is it water resistant,
and should never be immersed in water.
If any liquid gets into the device, immediately power the unit down (press and
hold the power button for more than three seconds). Disconnect the sensor and
charging cable, and remove the battery. Allow the device to dry thoroughly
before attempting to use the device again. Do not attempt to dry using an
external heat source.
Note: Damage due to liquid is not covered under warranty.
How the Sensor Works
Go Direct CO
2
Gas measures gaseous carbon dioxide levels in the range of 0 to
100,000 ppm by monitoring the amount of infrared radiation absorbed by
carbon dioxide molecules. Carbon dioxide gas moves in and out of the sensor
tube by diffusion through the vent holes in the sensor tube. The sensor uses a
small light to generate infrared radiation (IR). The IR source is located at one
end of the sensor’s shaft. At the other end of the shaft is an infrared sensor that
measures how much radiation gets through the sample without being absorbed
by the carbon dioxide molecules. The detector measures infrared radiation in the
narrow band centered at 4260 nm. The greater the concentration of the CO
2
gas
in the sampling tube, the less radiation will make it from the source through the
sensor tube to the IR detector.
The sensor also measures air temperature in the sensor shaft using a thermistor in
an integrated circuit. When the temperature increases, the resistance of the
thermistor decreases. The circuit measures the resistance value at a particular
temperature and converts this to a digital signal.
Relative humidity is measured in the sensor shaft using an integrated circuit that
uses a capacitive polymer to sense humidity. The circuit produces a signal
which varies with relative humidity.
Troubleshooting
l Very important: Do not place the sensor into any liquid. The sensor is
intended only for measuring gaseous, not aqueous, CO
2
concentration.
l Allow the sensor to warm up for at least 180 seconds before use. The warm-
up process begins when the sensor is charging, connected to a USB port, or
connected to software via Bluetooth wireless technology.
l The sensor is sensitive to high humidity. Do not use in a condensing
environment.
Accuracy ±0.5°C
Resolution 0.1°C
Relative Humidity Sensor
Type IC
Range 0 to 100% (non-condensing)
Accuracy ±5% or better
Resolution 0.1%
USB specification 2.0
Wireless specification Bluetooth 4.2
Maximum wireless range 30 m unobstructed
Battery 650 mA Li-Poly
Battery life (single full
charge)
~8 hours
Battery life (long term) ~500 full charge cycles (several years depending
on usage)
Normal operating
temperature range
20 to 40°C
Operating humidity range 5 to 95% (non-condensing)
Dimensions Sensor tube: 82 mm length, 28 mm OD; total
length: 200 mm
Care and Maintenance
Battery Information
Go Direct CO
2
Gas contains a small lithium-ion battery. The system is designed
to consume very little power and not put heavy demands on the battery.
Although the battery is warranted for one year, the expected battery life should
be several years. Replacement batteries are available from Vernier
(ordercode:GDX-BAT-650).
Storage and Maintenance
To store Go Direct CO
2
Gas for extended periods of time, put the device in
sleep mode by holding the button down for at least three seconds. The red LED
will stop flashing to show that the unit is in sleep mode. Over several months,
the battery will discharge but will not be damaged. After such storage, charge
the device for a few hours, and the unit will be ready to use.
Exposing the sensor to temperatures below –15°C or over 45°C will damage the
sensor. Additionally, temperatures over 35°C (95°F) will reduce the battery's