GAS91D Formaldehyde Gastec Passive Sampling Dosi Tubes (Time Weighted Average Detector Tubes)
The Dosi-Tube System allows an operator to evaluate the level of gas a worker is exposed to over a time period such as a working shift.
The Dosi-Tube is easily clipped into the dosi-tube holder (GAS710) which is worn on a garment of clothing.
|Measuring Range||0.1 to 20 ppm|
|Sampling Hours||1 to 10 hours|
|Detecting Limit||0.05 ppm (10 hours)|
|Colour Change||Yellow Reddish Brown|
|Reaction Principle||Formaldehyde reacts with hydroxylamine phosphate to liberate Phosphorous acid, which discolours pH indicator to reddish brown.|
|Coefficient of Variation||10% (for 1 to 20 ppm∙hr)|
|Shelf Life||Up to 1 year from point of manufacture|
temperature & humidity
|Store the tubes in the refrigerator to keep at 10oC (50oF) or below.|
|Possible coexisting substances and their interferences|
|Substance||Interference||Change colour by itself|
|Aldehydes, Ketones, Acid gases||Plus error||Discolours reddish brown|
|Other substance measurable with this detector tube|
|Substance||Correction Factor||Sampling Time||Measuring Range|
|Acetaldehyde||1.0||1 to 10 hours||0.1 to 20 ppm|
|Furfural||3.0||1 to 10 hours||0.3 to 60 ppm|
|Methyl Ethyl Ketone||1.25||1 to 10 hours||0.125 to 25 ppm|
|Calibration gas generation||Diffusion tube method|
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