Gastec Phenol Detector Tube features 4 pump strokes and 0.4 correction factor for 0.4 - 1 ppm measuring range, 2 pump strokes and 1 correction factor for 1 - 25 ppm measuring range, 1 pump strokes and 2.5 correction factor for 25 - 62.5 ppm measuring range and 1/2 pump strokes and 7.5 correction factor for 62.5 - 187 ppm measuring range. Detector tube with sampling time of 1.5 min per pump stroke is ideal to detect phenol in air or the industrial areas and environmental atmospheric condition. Detector with 0.1 ppm detecting limit, changes color from pale yellow to gray.