GAS4M Hydrogen Sulphide Gastec Detector Tubes 12.5 – 500ppm

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GAS4M Hydrogen Sulphide (H2S) Standard Gastec Detector Tubes

Gas detector tubes are glass tubes that are filled with chemical reagent that absorbs and reacts with the target gas or vapour being measured.

A colorimetric stain (a colour change) is created. For most tubes, the concentration is read directly from the pinpoint accurate measurement scale on each tube.

This makes this form of monitoring ideal for spot sampling as it can be more accurate then electronic gas detectors.

The Gastec detector tube system is comprised of a handheld Gastec air sampling pump and Gastec detector tubes.

Measuring Range 12.5 to 25 ppm 25 to 250 ppm 250 to 500 ppm
Number of Pump Strokes 2 1 1/2
Correction Factor 1/2 1 2
Sampling Time 30 seconds per pump stroke
Detecting Limit 2.5 ppm (n=2)
Colour Change White       Brown
Reaction Principle Hydrogen Sulphide reacts with Lead Acetate to form Lead Sulphide, which colour is brown.

H2S + Pb(CH3COO)2                PbS + 2CH3COOH

Coefficient of Variation 5% (for 25 to 250 ppm)
Shelf Life 3 Years
Corrections for
temperature & humidity
Store the tubes at cool and dark place.


Possible coexisting substances and their interferences
Substance Concentration Interference Change colour by itself
Nitrogen Dioxide 1/4 time Minus error No discoloration
Sulphur Dioxide 1/1 time Plus error No discoloration
Mercaptans No effect No discoloration
Calibration gas generation Permeation tube method

Additional Information

Weight 0.1 kg
Multi Gas Tags

Gas Range



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