We can analyze the maintenance knowledge required for ultrafiltration equipment based on the characteristics of electrophoresis ultrafiltration systems.

　　Most people know that electrophoretic coating uses water-based paints, with water serving as the dissolving medium. Its key advantages include significant savings in organic solvents, drastically reducing air pollution and environmental risks, while also enhancing safety and hygiene—and eliminating fire hazards altogether. Electrophoretic coating equipment boasts high coating efficiency and minimal paint wastage, achieving a paint utilization rate of over 95%. This process ensures uniformly smooth coatings across all parts of the workpiece, including uneven surfaces, recesses, welds, and internal areas, effectively addressing the challenges of coating complex-shaped components that are often difficult to handle with conventional methods. However, a notable limitation of electrophoretic coatings is that they can only accommodate water-soluble paints. Additionally, once the coating process begins, color changes are impossible, and prolonged storage of the paint can lead to instability, making it harder to maintain consistent quality over time.

　　Maintenance of the ultrafiltration system in electrophoresis ultrafiltration equipment is crucial, which is why special attention is given to maintaining the ultrafiltration system. The ultrafiltration system serves two primary functions: First, it ensures an effective closed-loop washing process by providing sufficient filtrate and removing water-soluble impurities from the paint, thereby enhancing the utilization rate of the electrophoretic coating. Second, managing the ultrafiltration system hinges on monitoring its permeate flow rate—specifically, checking and recording the system’s flow daily. If any abnormalities are detected, immediate corrective actions must be taken; for instance, if the permeate flow drops below 70%, a cleaning procedure should be scheduled without delay.

　　The reasons for the low throughput can be broadly categorized into the following sections.

　　1. The ultrafiltration equipment is experiencing low flow rates. Adjusting the pressure settings has not resolved the issue, and coarse filtration remains inadequate, causing the equipment to frequently stall (stopping for more than 1 hour), resulting in reduced throughput—and in severe cases, even leading to damage of the membrane (ultrafiltration membrane). 2. The liquid temperature in the tank is too high. 3. The filter bags are clogged. 4. The particle size in the filter bags is too large. 5. The activation layer of the ultrafiltration membrane has failed: This layer works by converting the polarity of charged materials into the same polarity as the bath liquid itself. However, its effectiveness is time-limited, with optimal durability lasting up to several months under ideal conditions. If the activation layer deteriorates, it must be restored through a thorough cleaning process. When cleaning, strictly follow the prescribed formulation and proportions for the cleaning solution, and carefully adhere to the recommended cleaning procedure. Failure to do so could lead to irreversible damage or complete failure of the ultrafiltration membrane.

　　Three Common Methods for Cleaning Ultrafiltration Equipment

　　1. Regular daily cleaning (once a month)

　　a. Check whether the cleaning tank is filled with purified water or ultrafiltrate. b. Close the membrane assembly and the paint inlet/outlet valves; then open the cleaning inlet/outlet valves for the membrane assembly. c. Close the valve on the ultrafiltrate collection tank, open the tank’s outlet valve, and also open the cleaning tank’s inlet valve. d. Open both the inlet and outlet valves of the cleaning pump, then start the pump. e. Use the ultrafiltrate/purified water from the cleaning tank to return the paint from the membrane assembly back into the electric swimming tank—approximately two-thirds of the wash tank’s volume. f. Close the membrane assembly and the paint inlet/outlet valves again; then reopen the cleaning inlet/outlet valves for the membrane assembly. g. Fill the cleaning tank completely with purified water. h. Allow the circulation cleaning process to continue until the pump automatically stops after about 240 minutes. i. Inspect the circulating liquid for any significant presence of paint; if so, you may need to increase the number of cleaning cycles. j. After completing the cleaning process, switch to the parallel line for continued operation.

　　2. Chemical Cleaning

　　A. Add purified water to the washing tank and replace it with the regeneration solution. The regeneration solution typically consists of either (30% butylene glycol, 5% lactic acid, and 65% water) or the solvent NHF-01 additive (30%) combined with NHF-02 additive (25%), topped off with pure water to make up the remaining 45%. Ensure the washing solution temperature does not exceed 45°C. B. After rinsing with the regeneration solution, repeat the standard daily cleaning procedure by thoroughly rinsing with purified water until completely clean.

　　3. Sterilization and Cleaning

　　A. Add purified water to the washing tank and replace it with a disinfectant (follow the disinfectant’s instructions for proper dilution ratio). Ensure the washing solution temperature does not exceed 45°C. B. After disinfection cleaning, repeat the standard daily cleaning procedure by thoroughly rinsing with purified water.

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