[sky753]

Thank you very much for your prompt reply.It has given me a great help.
I have make corrections as follows.I am wondering whether it is ok?


place the tempered glass lid horizontally onto the 20 mm wooden board with the concave side downward, drop one 225g steel ball from certain height (For grade A the height is 1500mm,grade B 1250 mm,and grade C 1000mm) to strike the middle circular part between the central hole of the lid and its edge. The width of the circular part is one third ofthe radiusofthe tempered glass lid. The fanning part around the vent shall be kept away from the ball dropped. (The fanning part is between the two lines drawn from the central hole,whose included angle are 90 degrees and which are symmetrical to the linejoining the central hole and the vent .)Followed by strength resistance testing is the heat and temperature difference resistance testing.


And as for the fanning part ,I mean the part in a circle.Draw two lines from the center of the circle whose included angle are 90 degrees to join the circumference.Then how do we call the part among the two lines and the arc?

Thanks

Richard