| Operation Steps：
1. Prepare the glass lid; adjust the height of impact rack to 1.5m and fix it tightly.
2. Take the steel ball with net weight 227g±2g and make it free falling from the fixed position, than check the impact point and mark it as the falling point.
3. Put the lid on the impact platform, adjust the falling point to 1/6 position of the lid edge(No near to the knob and steam holes), than the steel ball fall free from the fixed position.
4. Check the glass lid broken or not. No broken is qualified.