CMCD differential pressure on-line densitometer is an automatic measuring instrument for on-line density measurement of various liquids or liquid mixtures. In the petroleum industry, it is widely used in the detection of oil, oil refining, oil blending and oil-water interface. In the food industry production site for grape juice, tomato juice, fruit syrup, vegetable oil and soft drink density detection: in the paper industry for black pulp, green pulp, white pulp and alkali solution density detection; In the chemical field, it is also used for the detection of detergent, glycol, carbonic acid, urea and polymer density: it is also widely used in the pharmaceutical industry, dairy industry, mining industry and so on.