The knowledge of the carcinogenic effect of benzene on the human body has improved over the last few years. Moreover, we know that exposure to benzene may cause irritation to the eyes, nose and respiratory tract, which may result in headaches, dizziness, convulsions, coma and even death.
To minimize the risks affecting the health of workers exposed to this hydrocarbon, the exposure concentration recommended by the National Institute for Occupational Safety and Health (NIOSH) is now about 0.1 ppm.
To address these issues, the worker must use the proper measurement technology for benzene concentration. Many different technologies are available on the market, such as colorimetric gas detector tubes.
Colorimetric gas detector tubes are made of glass and used for the short-term measurement of benzene concentration in the environment.
The method of the operation
The use of tubes may only be possible if the user has a hand pump with a tube cutter as well as the instruction manual provided with the tubes.
To measure the concentration, cut both tips of the tube and then, insert with the arrow pointing towards the hand pump. Using the pump, the user must draw in the air sample through the tube to pull in the entire colored length. The number of pump strokes is indicated on the tube with a “n=” (if n=4, the user must pump 4 times before the reading). In this case, benzene will provide a clear color change in the tube. The scale printed on the tube will allow for a reliable reading.
The benefits of using tubes
Using tubes offers many advantages.
Tubes are a quick reading that only takes a few seconds, and the scale printed on the tube allows for a reliable measure.
Also, there are more than 200 different types of gas detector tubes to measure over 500 different gases and vapours, therefore making it a very versatile product.
Gas detector tubes are also very easy to use.
The tubes are useful in many different industries.
Standard and relative deviation
During a measurement using colorimetric tubes, the standard deviation and relative deviation are not to be disregarded. When measures are taken using a tube in an environment where the ambient temperature is between 0 and 30⁰C, add a 15% variation, and when the temperature is between 31 and 40⁰C, add a 25% variation. The addition of these deviations is mandatory to ensure an accurate measurement. This new measure is the one that must be stated on the entry reports.
Hand pump
Drager colorimetric tubes can only be used with a pump of the same brand: using any other pump may alter the proper functioning of the tubes. Also, the hand pump must be tested for leakage every three (3) months to ensure the value of the measure.
Interferences with other gases
When the user performs a gas detection measurement using colorimetric tubes, it is essential to have an idea of the other gases potentially in the atmosphere; tubes are subject to react when in contact with other air contaminants and the reading may be affected.
Expiration date
Finally, another significant element when using Drager colorimetric tubes is to verify the expiry date indicated on the package. Tubes past their expiration date will provide an erroneous reading of the air contaminants.
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