Gas detection: two mistakes to avoid

Gas detection: two mistakes to avoid

1/29/2015 - SPI

We are fortunate to rely on the best performing gas detectors ever made. However, the user often makes certain mistakes. Fabien Demers, SPI Senior Advisor and Trainer, would like to draw your attention to two important mistakes still occurring too often in the workplace.

1) Incorrectly interpreting the result during sampling

Here is a real-life situation frequently observed: the user is required to sample inside a manhole on the street or a confined space with a vertical entry.

First, not all gas detectors have a sampling pump with a tube to take a reading from the outside. To remedy this situation, the sampler lowers the detector using a rope while respecting all detection principles.

As he retrieves the device, the sampler checks the screen of the detector. What does he see? Normal values. Why is that so? Detectors display in real time. This is a direct reading. Thus, the displayed values reflect the situation outside the manhole! “Many people are surprised when we point it out,” indicates Fabien Demers. How can we correct the situation? Easy! All you have to do is retrieve the maximum values recorded during the reading. All gas detectors have this feature. But you must know your detector. However, all previously gathered data must be deleted before performing the sampling.

2) Lack patience while waiting for the data to be displayed

Although gas detectors show the information in real time, we still need to wait a little for it! Too much haste prevents us from obtaining the real results.

When detecting a smell with our nose, we need a few moments for our brain to interpret the result. It’s the same process with the gas detector. We need to allow time for processing and displaying the right values. How can we know it is the case? “If I refer to the T90, do you know what I mean? It is a question frequently asked to users by our expert advisors and trainers,” adds Fabien Demers.

The T90 is the time it takes for displaying 90% of the gas concentration to detect. The data are different for each detector according to the sensors used. To learn more about these values, refer to the manufacturer’s manual.

Would you like to see for yourself? Simple. Take the cylinder used to verify and calibrate a detector. When the detector is in reading mode, plug your cylinder and open the valve. See how the detector behaves. You will realize it takes a moment for the detector to display the data. Also, if you take CO as an example, the cylinder contains probably 100 ppm. Time how long it takes for your detector to reach 90.

For your next readings, allow the required time for your detector to display the accurate values.

Avoid unnecessary risks

The best way to ensure your users are qualified (to use, sample or interpret) and know their detector inside out, is to offer them a training tailored to their needs.

SPI takes them into account to build customized trainings in contaminant detection. You will become more efficient while saving money.

An interesting tool for gas detection

MSA offers an interesting tool for users. It is a gas detection simulator online for some newer models. Our expert advisors and trainers use it to teach, but also for remote interventions. Fabien Demers indicates that he helped a user in Fermont (Quebec). He needed to review key components to perform calibration and bump test on these detectors. 

Contact us to learn more about the selection of a gas detector adapted to your needs, and have more information on the sales or rental services offered.