Gastec Nitric Acid Gas Detector Tube features 2 - 10 pump strokes and 1/2 - 1/10 correction factor for 0.1 - 1 ppm measuring range, 1 pump strokes and 1 correction factor for 1 - 20 ppm measuring range and 1/2 pump strokes and 2 correction factor for 20 - 40 ppm measuring range. Detector tube with sampling time of 30 sec per pump stroke is ideal to detect nitric acid in air or the industrial areas and environmental atmospheric condition. Detector with 0.05% detecting limit, changes color from yellow to reddish purple.