1. Visual and Tactile Inspection (Most Direct)
Surface Condition: A dried metal can should be free of water stains and condensation, and the inner wall should be free of visible water droplets or damp reflections.
Touch Verification: Wearing clean gloves, touch the inner wall of the can. It should feel dry and sticky. Fingerprints or slight adhesion indicate residual moisture or unevaporated cleaning agent.
Welds and Dead Corners: Focus on inspecting areas prone to water accumulation, such as bottom welds and flange connections. Use a flashlight to observe for shadows or moisture buildup.
✅ Tip: For dark or reflective surfaces, observe under strong light from multiple angles to avoid visual misjudgment.
2. Weight Change Monitoring (Quantitative Judgment)
Principle: Moisture evaporation causes a continuous decrease in the can's weight. When the weight stabilizes, it indicates that drying is basically complete.
Operating Method: Record the initial wet weight of the tank after cleaning using an electronic scale;
Weigh the tank every 30 minutes and plot a "time-weight" curve;
When the difference between two consecutive weighings is less than 0.5% of the total weight, it can be considered substantially dry.
Applicable Scenarios: Suitable for batch processing and automated production lines, especially for reuse tanks with high cleanliness requirements.
3. Environmental Humidity Monitoring (Auxiliary Guarantee)
Ideal Drying Environment: Relative humidity should be controlled below 60%, and the temperature should be maintained at 120~170℃ (hot air drying) or 60~70℃ (infrared drying).
High Humidity Risk: If the ambient humidity is >70%, even if the surface is dry, the metal surface can easily absorb moisture from the air, forming "rewetting"; Especially in the rainy season or coastal areas, it is recommended to use a dehumidifier or nitrogen purging to prevent moisture re-entry after drying.
Monitoring Tools: Use a thermometer and hygrometer to monitor the drying room or storage area in real time to ensure that the drying process is not disturbed by external factors.
⚠️ Note: Ambient humidity is for reference only and cannot replace the actual condition of the tank. It must be judged in combination with the first two methods.
