1) Manual control

This is the common practice of most small and medium-sized PS plate manufacturers in China. Mainly in the entire production line of data management system has not yet formed, the degree of automation is low, the surface treatment process for a variety of acid-base treatment liquid detection is often only the instrument display, and no automatic real-time control. The concentration test is completed by artificial laboratory titration. The supplement fluid is also artificially performed by experience. Therefore, it is greatly influenced by human factors.

1 regular inspection. In the production line, each acid-base solution tank in the surface treatment process section is equipped with a corresponding acid-base concentration detection device, a cassette-type or wall-mounted display panel, and shows the acid or alkali in the tank. The real-time concentration of the liquid. In the normal production process, as the reaction progresses, the concentration of various acid-base solutions will be reduced or changed in varying degrees. Therefore, workers will regularly inspect the indications of various instruments according to certain shifts. After a regular inspection, the worker informs the inspector to sample and test the actual concentration of the treatment fluid. In addition, if there are problems in the production process that affect the quality of the finished media, the workers will also sample the surface treatment fluid.

2 laboratory titration test. The concentration of the solution is measured in the laboratory through titration. The inspector determines the endpoint of the titration according to the color change of the indicator, and then calculates the analytical result based on the volume consumed by the standard solution to obtain the exact concentration of the treatment solution.

3 artificially added. The worker who is responsible for supplementing the stock solution shall, after receiving the notification from the inspector, add a certain amount of stock solution to the treatment box according to the corresponding concentration difference to restore the concentration of the solution required by the process. The amount of specific supplement fluid is often based on the practical experience of workers for many years, gradually explored a certain amount of experience.

2) Semi-automatic control

At present, some companies design a "semi-automatic" solution concentration control device based on manual control.

In the production line, each surface treatment liquid circulation tank is equipped with a corresponding acid and alkali concentration detection instrument, an external display panel is connected through the wire, and the concentration value of the acid liquid or alkali liquid in the circulation tank is displayed in real time. At the same time, there is a pipeline from the raw liquid storage tank to the processing liquid circulation tank, and a certain amount of liquid is controlled by the valve to continuously add the original liquid to the processing tank to maintain the concentration of the treatment liquid in the tank.

The real-time dripping amount of raw liquid is discovered by the workers with many years of actual production experience. With the different vehicle speed conditions and production conditions, a set of empirical data is gradually formed, which is generally measured and controlled with “drip/minute”.

3) Automatic detection and control

At present, some large-scale PS plate production enterprises at home and abroad have adopted automatic concentration detection systems for treatment liquids. Computer control and display are used to achieve automatic detection of solution concentrations and automatic replenishment of raw liquids. Such systems use advanced acid concentration sensors, acid temperature sensors and corresponding smart meters. Shanghai Printing Online detects the concentration and temperature of each surface treatment liquid, and controls the concentration and temperature of the liquid through the automatic interface and the computer's total control cabinet. Connected, the test results are transmitted to the central controller for calculation and processing, and then the controller issues control commands to drive the acid-resistant and alkali-resistant solenoid valves to control the automatic addition of the treatment liquids such as hydrochloric acid, sulfuric acid, and deoiling section alkali liquor. It achieves automatic control of surface treatment solution concentration and temperature. Due to the high real-time and accuracy of the automatic control, the quality of the sand quality of the plate base and the quality of the oxide film layer are well guaranteed.