Vaisala GM70 - Manual (Page 19)

Chapter 4 ______________________________________ Measuring Carbon Dioxide
VAISALA __________________________________________________________ 19
CHAPTER 4
MEASURING CARBON DIOXIDE
This chapter consists of instructions on how to do carbon dioxide
measurements.
The results of carbon dioxide measurements are affected by the air
pressure and the temperature of the measurement conditions. For
achieving the most accurate measurements in high altitudes where the
barometric pressure is clearly lower than in the sea level, the actual
atmospheric pressure value should be set to the GM70. The acceptable
pressure value range is 700 ... 1300 hPa.
NOTE Before measurements ensure that the air pressure and temperature
settings are correct. Set the correct settings as instructed in section
Setting Actual Pressure Value and Unit on page 27.
Taking Measurements (Diffusion Sampling
With GMH70 Handle)
See Chapter 3 Preparations Before Use on page 17 if you start the GM70
for the first time, otherwise follow the instructions below:
1. Connect the probe cable to the MI70 indicator's connector port.
2. Press POWER ON/OFF button.
3. Wait for about 15 seconds to get the reading. For the most accurate
readings wait for 15 minutes to reach the full operating state of the
GM70.
4. Install the probe to the measuring position. Avoid exhaling near the
probe as this increases the CO
2
concentration.
5. The basic display opens, allow the reading to stabilize.