Monitoring hazardous environments for gas requires three basic necessities:
1) the appropriate gas monitoring equipment for the job
2) good technique
3) adequate knowledge, experience and understanding of how the tools work and how to use them correctly.
Why We Need to Monitor Air Quality
Monitoring air composition is necessary to detect dangerous gases that could potentially pose a risk to the safety of workers. Hazardous gases, such as carbon monoxide (CO), are often odorless and colorless and therefore difficult to detect without the appropriate gas monitoring equipment. Additionally, low oxygen levels can lead to loss of consiousness and eventually death if this is not detected to allow workers to don safety oxygen masks where necessary. To ensure worker safety, they should be equipped with suitable Gas monitoring equipment
that is capable of detecting all the hazardous gases anticipated in their work environment.
Good Gas Monitoring Technique
In order for workers to consistently be able to detect any potential atmospheric hazards with accuracy, they need to have good technique. This requires an understanding of both the science of gas monitoring and detection, and the capabilities and limitations of their equipment. For example, certain gases -- such as methane, hydrogen and ammonia -- are light and are more inclined to rise, while others are heavy and thus more likely to sink. Therefore, when trying to detect for a certain gas it is important for workers to monitor at the location it is most likely to be found, and when monitoring for unknown gases that checks are done at both low and high levels to avoid hazardous gases going undetected.
Understanding the Limitations of Gas Monitoring Equipment
Furthermore, sensors on gas monitoring may take some time to show a response. Some sensors, such as those found on photoionization detectors (PIDs), respond relatively quickly in a matter of seconds, while others, for example electrochemical sensors, respond a little slower at 20-40 seconds. So, in reality, say it takes 40 seconds to move through a tunnel, or from one door to another, your gas monitor may still be analyzing the air at the entrance/first door, while you have crossed through a dangerous and potentially life-threatening environment while it is still busy analyzing the air at the entrance. It is paramount that workers are aware of the response time of the gas monitoring equipment they are using. This is usually listed in the user manual as t90 (time the sensor takes to attain 90% of the full reading) -- if there are any hoses attached, add 1-2 seconds for each foot of attached hose.
Using Gas Monitoring Equipment
Monitoring should be conducted routinely and systematically as workers approach an area deemed to be potentially hazardous. Workers need to have sufficient training and experience to know what Gas monitoring equipment
to utilize and when to use it. This means that they must take the necessary equipment with them when entering a hazardous environment, and must know when to use it, how to use it correctly, and how to understand the readings.
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