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Technical FAQ’s

Carbon dioxide can be measured by two different detection principles. The electrochemical detection is a low cost detection principle, but leads to high maintenance costs (1 year durability). What is more serious is safety. If the ambient air contains H2S, the display of the CO2 transmitter reads a lower CO2 value than what is actually present, due to cross-sensitivity.

Worst case scenario: The transmitter displays a “zero” even though both gases are present! When the sensor drifts, the maximum deviation for the electrochemical sensor (5%), is reached after 10 days. This occurs when the sensitivity of the sensor is extremely high. This means that such a monitor needs to be calibrated every 10 days. This is not practical in the course of business. Moreover, supplying high concentrations of CO2 to the monitor poisons the electrochemical sensor.

In contrast to this, the infrared detection principle has higher initial costs, but longer durability, the smallest maintenance intervals, and no cross-sensitivity to ambient gases.

No. The ambient air contains 20% oxygen and 80% nitrogen. If the carbon dioxide concentration increases, oxygen and nitrogen are displaced by the carbon dioxide in a 4:1 ratio.

Carbon Dioxide CO2 Oxygen O2 Nitrogen N2
0% 20% 80%
4% 19% 77%
8% 18% 74%
12% 17% 71%
16% 16% 68%

To decrease the oxygen concentration by 1%, the carbon dioxide concentration has to increase by 4%. Oxygen monitors activate the alarm at 17% volume. By this time, the carbon dioxide concentration has already reached a concentration leading to death.

Numerous factors influence this decision: the type of gas, potential leaks, and ventilation all have an influence on the number of transmitters and the mounting places. This question cannot be answered by giving an area in square meters. Please refer to your local GfG sales representative for more information.

Ammonia (NH3) is lighter than air. For ammonia monitoring, the transmitter needs to be placed as high as possible. Always make sure that the transmitter is placed higher than every potential leak.

If the detection range is exceeded, the transmitter gives a signal that can not be overruled by the monitor. The monitor (e.g. G750 or GMA 101) will display that the gas concentration is over range. GfG uses only infrared sensors (IR) for carbon dioxide monitoring. These transmitters cannot be damaged, even by high CO2 concentrations.