Dräger
Hydrogen sulfide (H2S), commonly known as sewer gas or sour gas, is incredibly lethal. Any inhalation of H2S in a high concentration can cause death. In fact, among deaths from gas inhalation in the workplace, H2S remains the leading cause.
It's important gas monitors' sensor speeds be considered when selecting the right instrumentation. Although a 5-second disparity may seem insignificant, those few seconds can determine whether or not a worker walks away or is stricken during an event. Early detection of harmful gas is of the utmost importance, so it's vital gas monitors featuring rapid sensor speeds be used, because they are commonly the first line of defense in protecting workers.
The new American Conference of Governmental Industrial Hygienists' (ACGIH's) H2S threshold limit value recommendation reinforces the importance of early detection. ACGIH has suggested lower thresholds for detection of hazardous gases, and the preparedness of organizations to meet this threshold can be strengthened by the use of instrumentation with a quick sensor speed.
The following scenario illustrates the importance of rapid sensor speed during an H2S event, showcasing the difference between a sensor with a t-90 time (the time it takes for a sensor to read 90 percent of the test gas concentration) of 15 seconds versus a sensor with a t-90 time of 25-40 seconds.
When H2S is simultaneously introduced to these two monitors, neither monitor will immediately react. After a few seconds, the instrument with a t-90 time of 15 seconds will begin to register a gas amount. The device that has a t-90 time of 25-40 seconds will show no digital readout. The numbers on the device with the t-90 time of 15 seconds will climb until they read 10 ppm.
At this point, the device with the longer t-90 time will have yet to register a reading. The worker wearing this device will start to suffer from a decreased level of muscle activity and oxygen in the blood, and will experience this for a total of 10 seconds without the alarm sounding. As the gas concentrations increase, both monitors will continue to respond to the gas.
After 1 minute and 35 seconds, the device with the 15-second t-90 time will measure 15 ppm and go into an A2 alarm. The worker wearing this monitor will then be able to evacuate the area. Even though the monitor with the longer t-90 time will have been exposed to the same level of gas for the same amount of time, it will take an additional 42 seconds for it to reach a full A2 alarm.
During these 42 seconds of 15-ppm exposure, the worker may experience eye irritation, headache, dizziness, nausea, throat irritation, coughing and difficulty breathing. Additionally, by the end of these 42 seconds, the actual level of exposure will have risen to nearly 20 ppm. At this point, all previous symptoms will continue to worsen and memory loss may occur.
As employers strive to keep their workers safe, it's essential their crews are equipped with tools that will warn them of harm before it's too late. Using a device with a lower t-90 time can help employers achieve a higher degree of safety and assure workers they have the mechanism needed to quickly and effectively escape harm.
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