Titration is a quantitative analysis method that determines the content of a solute by quantitatively reacting two solutions. In the methyl orange acidity online detector, the titration method is used to measure the methyl orange acidity in water samples. It relies on chemical reactions between the two solutions and color changes in the indicator to determine the titration endpoint. As an indicator, methyl orange's color changes can sensitively reflect changes in the concentration of hydrogen ions in the solution. At the titration endpoint, the color of methyl orange changes, indicating that the reaction has reached the predetermined acidity value. During titration, a standard base solution of known concentration (such as sodium hydroxide solution) is slowly added to the water sample to be tested. With the addition of the alkaline solution, hydrogen ions in the water sample are neutralized, and the color of methyl orange gradually changes. When methyl orange changes color from yellow to orange (or from red to yellow, depending on the specific pH range and the color change point of methyl orange), the titration is considered to have reached its endpoint. At this point, the volume of standard base solution consumed can be used to calculate the methyl orange acidity in the water sample.