Gastec Nitrogen Dioxide Detector Tube features 2 pump strokes and 1 correction factor for 3.3 - 10 ppm measuring range and 1 pump strokes and 1 correction factor for 30 - 125 ppm measuring range. Detector tube with sampling time of 30 sec per pump stroke is ideal to detect nitrogen dioxide in air or the industrial areas and environmental atmospheric condition. Detector with 0.1 ppm detecting limit, changes color from white to yellowish orange.