The evaluation method for the performance of the anti-foam agent
（1）Light intensity method: according to the scattering and transmission characteristics of bubbles to foam, when the light with a certain intensity passes through the foam in a certain area, its transmission light intensity will be greatly reduced. According to the change of transmission light intensity, the change of foam amount can be directly reflected, so as to compare the performance of the antifoaming agent. The greatest advantage of this method lies in the timeliness of detection and continuous data processing.
(2) conductivity method: because foam is a mixture of gas and liquid, when the solution contains conductive ions, the liquid in the foam system conducts electricity while the gas does not conduct electricity, so the content of foam can be measured according to the size of conductivity, so as to compare the performance of the antifoaming agent. The advantage of this method is high sensitivity and accurate measurement, but this method is not suitable when the antifoaming agent has influence on the conductivity.
（3）Camera photography: this method first uses light to illuminate the foam area, and uses CCD to take the sampling area. Then, the image is analyzed through certain image processing technology, and the foaming agent is compared with the foaming agent by comparing the foaming changes in the images before and after the addition of the foaming agent. The biggest advantage of this method is the intuition, but it requires that the addition of defoaming agent should not affect the quality of the picture due to the color change.
（4）Sound detection method: when the foam breaks, it will make a sound because the liquid film moves too fast. According to this principle, the breaking rate of the bubble can be detected by measuring the sound size, so as to compare the breaking rate of the defoamer. The disadvantage of this method is that it requires strict background noise and is not sure about the degree of bursting of the bubble.
（5）Flow visualization method: Foam cannot be produced without liquid, The task of flow visualization is to visualize the motion of the liquid, these can be used in the foam technology such as holographic and infrared imaging technology, or in the case of bubble content is less, with a high speed camera device, The number of bubble contents and the number of bubbles in the foam were then compared to compare the advantages and disadvantages of different defoamers However, this method is similar to camera photography and has certain limitations in application.
All the methods above have certain application prospects for the performance detection of field defoaming agents, which makes it possible to develop a convenient, feasible, accurate and rapid detection instrument, which has certain research value, and represents the development direction of the performance detection of defoaming agents.