Oxygen Gas Detector for Woking in Confined Spaces

In confined spaces, either sewers or cellars, the oxygen content might be too high or too low. Meanwhile, toxic and hazardous gases might be included therein. Without adequate ventilation, and before using the oxygen gas detector or other toxic gas detector for detection, it is very dangerous to enter the airtight spaces. Then, how can we enter the airtight spaces safely? We should first know whether the oxygen is inadequate or too high in these confined spaces.

The most commonly-seen damage caused by the oxygen concentration to the human body is caused by the pathological process of the human body caused by hypoxia. More seriously, major organs, including heart and brain, might be dead because of hypoxia. In fact, when the oxygen gas detector is used to detect the oxygen content in confined spaces, one should not only consider suffocation and shock caused by entry of personnel caused by a too low oxygen concentration. Under some conditions, the airtight space might also cause unpredictable chemical responses or intensification of combustion when the oxygen content is too high.
The oxygen content in the normal air is around 2.9%. Among its constitutive gases, the nitrogen accounts for more than 78%. The remaining gases, including CO2, water vapor and CO, are trace gases. Therefore, the zero-point of an oxygen detector (namely the display concentration of the oxygen gas detector under the normal environment) set the calibration concentration of the oxygen sensor to be 20.9% or 21.0%.

In most airtight spaces, the oxygen concentration standard is measured by the volume concentration. When the concentration detected by the oxygen gas detector is less than 19.5% of the total gas volume, we can confirm that the oxygen is inadequate in the current environment. When the oxygen detector's reading exceeds the volume concentration of the oxygen in a normal environment by 22%, we can confirm that the oxygen content has exceeded the upper limit in the current environment. A reasonable alarm value should be set for the oxygen gas detector no matter whether the detection results are too high or too low. This can remind personnel of adopting the most timely and correct decision when the current environment’s oxygen concentration has reached the level, which might pose a threat to the personal or environmental safety, Besides, when the oxygen gas detector finds that there is super-high-concentration (23.5% of volume concentration) exists in the oxygen environment, the oxygen detector should be intrinsically safe, and the concentration upper limit of the oxygen gas detector should be strictly adhered to without using it to measure the excessive oxygen.

In the practical life and work scenarios, the oxygen concentration, if being around 20.9%, can be considered normal. Under other concentrations, it means the current oxygen concentration is abnormal. When the oxygen content is lower than the normal content, it means that the other gases in the gas are abnormal or that there are contaminated gases. At the moment, if the reading of the oxygen gas detector has not reached a dangerous level, causes of abnormal oxygen content should be identified before personnel enter the environment to be measured.