Easy operation:
Step 1: Record Start Time
Step 2: Break tube end
Step 3: Place in tube holder
Step 4: When measurement is finished, write down finishing time
Step 5: Find the TWA using the formula; TWA (ppm) = Dositube reading (ppm=hr) / Actual sampling time (hr)
Gas or Vapour to be Measured | Measuring Range (ppm) | Gastec Tube No. |
---|---|---|
Acetaldehyde | 0.1-20 | 91D |
Acetaldehyde | 4-1,200 | 151D |
Acetaldehyde | 1.2-360 | 152D |
Acetic Acid | 0.5-100 | 81D |
Acetic Anhydride | 0.45-90 | 81D |
Acetone | 5-1500 | 151D |
Acetone | 1.4-420 | 152D |
Ammonia | 2.5-1,000 | 3D |
Ammonia (Low) | 0.1-10 | 3DL |
Benzene | 2.4-600 | 122DL |
1,3-Butadiene | 1.3-200 | 174D |
Carbon Dioxide | 0.02-12% | 2D |
Carbon Monoxide | 1.04-2,000 | 1D |
Carbon Monoxide (Low) | 0.4-400 | 1DL |
Chlorine | 0.08-100 | 8D |
Chlorine | 2.4-240 | 132D |
Cumene | 3.4-850 | 122DL |
trans-1,2-Dichloroethylene | 3.9-600 | 174D |
trans-1,2-Dichloroethylene | 6-600 | 132D |
Dimethylamine | 1.9-750 | 3D |
N,N-Dimethylethylamine | 4-1,600 | 3D |
Ethanol | 100-25,000 | 112D |
Ethyl Benzene | 2.8-700 | 122DL |
Ethylene | 1.56-240 | 174D |
Ethylene dichloride | 3.9-600 | 174D |
Formaldehyde | 0.1-20 | 91D |
Formic Acid | 0.55-110 | 81D |
Furfural | 0.3-60 | 91D |
Hydrazine | 1.6-650 | 3D |
Hydrogen Chloride | 1-100 | 14D |
Hydrogen Chloride | 1.8-180 | 132D |
Hydrogen Cyanide | 1-200 | 12D |
Hydrogen Fluoride | 1-100 | 17D |
Hydrogen Fluoride | 2.5-250 | 14D |
Hydrogen Peroxide | 0.5-40 | 32D |
Hydrogen Sulphide | 0.2-200 | 4D |
Isoprene | 2.6-400 | 174D |
Methylamine | 0.19-19 | 3DL |
Methyl Ethyl Ketone (MEK) | 2-600 | 152D |
Methyl Ethyl Ketone (MEK) | 0.125-25 | 91D |
Methyl Ethyl Ketone (MEK) | 6.5-1,950 | 151D |
Methyl Isobutyl Ketone | 11.5-3,450 | 151D |
Methyl Isobutyl Ketone | 4-1,200 | 152D |
Ntric Acid | 0.8-80 | 14D |
Nitric Acid | 0.32-32 | 17D |
Nitrogen Dioxide | 0.1-30 | 9D |
Nitrogen Dioxide (Low) | 0.01-3.0 | 9DL |
Styrene | 26-6,500 | 122DL |
Sulphur Dioxide | 10-600 | 5DH |
Sulphur Dioxide | 0.2-100 | 5D |
Tetrachloroethylene | 3-150 | 133D |
Tetrachloroethylene | 1.5-150 | 132D |
Toluene | 2-500 | 122DL |
Trichloroethylene | 3-300 | 132D |
Triethylamine | 5.3-2,100 | 3D |
Trimethylamine | 0.23-23 | 3DL |
Vinyl Chloride | 1.56-240 | 174D |
Xylene | 3.4-850 | 122DL |
Gastec Passive Dosi-Tubes are used to measure time weighted average (TWA) gas concentrations over several hours. The Dositubes do not require the use of a sampling pump as ambient air diffuses through the tube.
Each tube is filled with a diffuser and chemical reagent in parallel that allows the gas to disperse at a constant flow. This provides longer discolouration and better demarcation. The tubes are normally attached to the worker’s collar or clothing in the breathing zone with the holder and collar clip.
- Uses gas diffusion method
- Tube holder clips onto workers collar for breathing zone measurements or can be used as an area monitor
- Measures time weighted averages (TWA) for numerous gases (See Dositubes List)
- Direct measurement can be made from the calibration lines printed on each tube