Coarsest Grain

Coarse Grain

Basic Grain

Mixed Grain

Fine Grain

Size Range
μm

Permitted grains

Size Range
μm

Not more than

Size Range
μm

Not more than

Size Range
μm

Not more than

Size Range
μm

Not more than

W63

100 – 80

1

80 – 63

15

63 – 50

50

63 – 40

80

< 40

5

W50

80 – 63

1

63 – 50

15

50 – 40

50

50 – 28

80

< 28

5

W40

63 – 50

1

50 – 40

15

40 – 28

50

40 – 20

80

< 20

5

W28

50 – 40

1

40 – 28

18

28 – 20

45

28 – 14

74

< 14

8

W20

40 – 28

1

28 – 20

18

20 – 14

45

20- 10

74

< 10

8

W14

28 – 20

2

20 – 14

20

14 – 10

45

14- - 7

72

< 7

8

W10

20 – 14

2

14 – 10

20

10 – 7

40

10 – 5

70

< 5

10

W7

14 – 10

2

10 – 7

20

7 – 5

40

7 – 3.5

70

< 3.5

10

W5

10 – 7

3

7 – 5

20

5 – 3.5

40

5 – 2.5

70

< 2.5

10