The reason for a negative reading on the gas detector is as follows
A gas detector is a device equipped with high sensitivity sensors that can sensitively sense small amounts of harmful and combustible gases commonly present in the air. It is a type of equipment that needs to be assembled in various fields of industrial production. The use of precision gas detectors can remind workers of the risk of exceeding gas standards at any time, ensuring the safety of workers. But in the use of gas detectors, sometimes negative readings may occur. So what is the reason for negative readings on gas detectors?
1. Zero reading in polluted atmosphere:
The situation where negative sensor readings are more common is when the instrument is "zeroed" when there is a small amount of target gas from the sensor in a polluted atmosphere. When the instrument is placed in a clean air environment later, the sensor will display a negative reading, corresponding to the concentration of pollutants at the time the equipment is zeroed. For example, when the sensor is zeroed, if the carbon monoxide concentration is 5 PPM, the reading will be -5 PPM when the sensor returns to clean air.
2. Negative cross interference:
When the sensor is placed in a gas that generates negative cross interference, negative readings may also occur. If the sulfur dioxide sensor typically has -100% cross interference with nitrogen dioxide and is placed in 2PPM of nitrogen dioxide, the sulfur dioxide reading on the instrument will be -2 PPM.
3. Pressure changes:
If the pressure changes dramatically (such as when passing through a gas plug), the gas detector reading may experience temporary fluctuations, which may cause the detector to sound an alarm. When the volume percentage of oxygen remains stable at around 20.8% and the overall pressure drops significantly, the oxygen used for respiration in the environment may become a danger.
4. Humidity changes:
If there is a significant change in humidity (such as when entering a humid outdoor environment from a dry environment with air conditioning), the water vapor in the air will drive away oxygen, causing the oxygen reading to drop by up to 0.5%. The gas detector is equipped with specialized filters to eliminate the impact of humidity changes on gas readings. This effect will not be immediately detected, but it will gradually affect the degree of oxygen after several hours.
5. Temperature changes:
The gas detector is equipped with temperature compensation, however, if the temperature fluctuates violently, the gas detector reading may experience drift. The instrument should be calibrated at the work site to minimize the impact of temperature changes on readings.
