Gastec Hydrogen Sulfide Gas Detector Tube features 10 - 2 pump strokes and 1/10 - 1/2 correction factor for 1 - 10 ppm measuring range, 1 pump strokes and 1 correction factor for 10 - 120 ppm measuring range and 1/2 pump strokes and 2 correction factor for 120 - 240 ppm measuring range. Detector tube with sampling time of 45 sec per pump stroke is ideal to detect hydrogen sulfide in air or the industrial areas and environmental atmospheric condition. Detector with 0.2 ppm detecting limit, changes color from white to brown.