S.I. No. 293/1950 - Standard Specification (Test Sieves) Order, 1950.


S.I. No. 293 of 1950.

STANDARD SPECIFICATION (TEST SIEVES) ORDER, 1950.

The Minister for Industry and Commerce, in exercise of the power conferred on him by subsection (3) of section 20 of the Industrial Research and Standards Act, 1946 (No. 25 of 1946), hereby orders as follows :

1. This Order may be cited as the Standard Specification (Test Sieves) Order, 1950.

2.—(1) The specification set forth in Part II of the Schedule to this Order is hereby declared to be the standard specification for the commodity described in Part I of the said Schedule.

(2) The said standard specification may be cited as Irish Standard 24 : 1950.

SCHEDULE.

PART I.

TEST SIEVES.

PART II.

SPECIFICATION.

In this specification the letters S.W.G. refer to Standard Wire Gauge and the letters B.G. refer to Birmingham Gauge.

SCOPE.

1. This specification covers the requirements of test sieves suitable for use in determining, by sieve analysis, the size of particles of a material.

CLASSES AND DESIGNATION.

2. Test sieves shall be of three classes : fine, medium and coarse. A test sieve shall be described by the designation given for it in Column 1 of Tables 1, 2 or 3.

WIRE CLOTH FOR FINE AND MEDIUM TEST SIEVES.

3. The sieving screen of fine and medium test sieves shall be wire cloth, uniformly woven to produce square apertures.

(a) Material. The material of the wire cloth shall conform to the requirements for material set out in Table 4.

(b) Weave. All wire cloth shall be plain woven, except the wire cloth for the No. 200 and No. 300 fine test sieves, which shall be plain woven or twilled. The wires of the cloth of medium test sieves, 1/8 in. to ½ in. inclusive, shall be crimped.

(c) Wires. The wires of the wire cloth of fine and medium test sieves shall have a circular cross-section. The average diameter of the warp and weft wires taken separately shall be within one half-gauge of the nominal diameter as set out in Columns 4 and 6 of Table 1 or 2. To determine the average diameter of the wire the procedure described in Appendix A shall be adopted.

(d) Aperture Widths. The aperture widths shall be measured on the centre lines of the aperture as indicated by the arrows in Fig. 1. To determine the aperture width the procedure described in Appendix B shall be adopted. The aperture width of each fine and medium test sieve shall be as set out for it in Column 2 of Tables 1 or 2 subject to the following tolerances, which shall apply in both the warp and weft directions separately :

(i) The average aperture width shall not differ from the nominal aperture width by more than the appropriate average tolerance shown in Column 8 of Tables 1 and 2.

(ii) The width of any aperture shall not exceed the nominal aperture width by more than the appropriate maximum tolerance shown in Column 10 of Tables 1 and 2. For this purpose the apertures measured shall be those which lie along two diameters of the test sieve, one across the warp and one across the weft.

PERFORATED PLATE FOR COARSE TEST SIEVES.

4. The sieving screen of coarse test sieves shall be plates perforated with square holes.

(a) Perforated Plates. The perforated plates shall be made from mild steel and shall be uniformly and cleanly punched, so that every aperture shows in its entirety after mounting. The thickness of the perforated plate of each test sieve shall be within one half-gauge of the nominal thickness set out for it in Columns 4 and 5 of Table 3.

(b) Aperture Widths. The aperture width of coarse test sieves shall be as set out in Column 2 of Table 3. An aperture width shall be measured along the centre lines of the aperture as indicated by the arrows in Fig. 1. The aperture width shall be subject to the following tolerances:

(i) The average tolerance of the aperture width shall not exceed that set out for the test sieve in Column 9 of Table 3.

(ii) The maximum positive tolerance in the width of any aperture shall not exceed that set out for the test sieve in Column 11 of Table 3.

(c) Width of Bridge. The width of metal between the apertures of coarse test sieves shall conform to the dimensions set out in Columns 6 and 7 of Table 3 subject to a tolerance of 1/32 in.

TABLE 1.—FINE TEST SIEVES.

DESIGNATION AND DIMENSIONS OF SIEVING SCREEN.

1 unit=1/10,000 in. 1 micron=1/1000 mm.

1

2

3

4

5

6

7

8

9

10

11

Designation of Fine Test Sieves

Nominal width of aperture

Nominal diameter of wire

Screening area approx.

Aperture tolerances

Average

Maximum

units

microns

units

microns

S.W.G.

units

per cent

units

per cent. approx.

No.5

1,320

3,353

680

1,727

15½

44

42

3·2

145

11

No.6

1,107

2,812

560

1,422

17

44

36

3·2

124

11

No.7

949

2,411

480

1,219

18

44

31

3·3

108

11

No.8

810

2,057

440

1,118

18½

42

27

3·3

94

12

No.10

660

1,676

340

864

20½

44

22

3·3

79

12

No.12

553

1,405

280

711

22

44

19

3·4

68

12

No.14

474

1,204

240

610

23

44

17

3·6

61

13

No.16

395

1,003

230

584

23½

40

14

3·5

53

13

No.18

336

853

220

559

24

36

13

3·9

47

14

No.22

275

699

180

457

26

36

11

4·0

41

15

No.25

236

599

164

417

27

35

10

4·2

37

16

No.30

197

500

136

345

29

35

8·7

4·4

33

17

No.36

166

422

112

284

31½

36

7·6

4·6

30

18

No.44

139

353

88

224

34½

38

6·7

4·8

27

19

No.52

116

295

76

193

36

37

5·9

5·1

25

22

No.60

99

251

68

173

37

35

5·2

5·3

23

23

No.72

83

211

56

142

38½

36

4·6

5·5

21

25

No.85

70

178

48

122

40

35

4·1

5·9

20

29

No. 100

60

152

40

102

42

36

3·7

6·2

19

32

No. 120

49

124

34

86

43½

35

3·2

6·5

18

37

No. 150

41

104

26

66

45½

37

2·9

7·1

17

41

No. 170

35

89

24

61

46

35

2·6

7·4

17

49

No. 200

30

76

20

51

47

36

2·4

8·0

16

53

No. 240

26

66

16

41

48

38

2·2

8·5

16

62

No. 300

21

53

12

30

49

41

1·9

9·0

15

71

TABLE 2.—MEDIUM TEST SIEVES.

DESIGNATION AND DIMENSIONS OF SIEVING SCREEN.

1 unit=1/10,000 in.

1

2

3

4

5

6

7

8

9

10

11

Designation of Medium Test Sieves

Nominal width of aperture

Nominal diameter of wire

Screening area approx.

Aperture tolerances

Average

Maximum

in.

mm.

in.

mm.

S.W.G.

per cent

units

per cent

units

per cent. approx.

1/32 in.

1/32

0·79

0·021

0·53

24½

36

15

4·8

45

14

1/16 in.

1/16

1·60

0·038

0·97

19½

38

21

3·4

76

12

1/8 in.

1/8

3·18

0·072

1·83

15

40

40

3·2

132

11

3/16 in

3/16

4·76

0·080

2·03

14

49

55

3·0

180

10

¼

¼

6·35

0·092

2·34

13

53

75

3·0

217

9

3/8

3/8

9·53

0·104

2·64

12

61

104

2·8

288

8

½

½

12·70

0·128

3·25

10

63

140

2·8

350

7

TABLE 3.—COARSE TEST SIEVES.

DESIGNATION AND DIMENSIONS OF SIEVING SCREEN.

1 unit=1/10,000 in.

1

2

3

4

5

6

7

8

9

10

11

12

Designation of Coarse Test Sieves

Nominal width of aperture

Plate thickness

Width of bridge

Screening area approx.

Aperture tolerances

Average

Maximum

in.

mm.

B.G.

in.

in.

mm.

per cent

units

per cent

units

per cent

3/16 in.

3/16

4·76

20

0·0392

3/32

2·4

44

12

0·64

25

1·33

¼ in

¼

6·35

18

0·0495

3/32

2·4

53

15

0·60

30

1·20

5/16 in.

5/16

7·94

18

0·0495

7/64

55

18

0·58

36

1·16

3/8 in.

3/8

9·52

18

0·0495

1/8

3·2

56

20

0·53

40

1·06

½ in.

½

12·70

16

0·0625

1/8

3·2

64

20

0·40

50

1·00

5/8 in.

5/8

15·88

16

0·0625

5/32

4·0

64

20

0·32

50

0·80

¾ in.

¾

19·05

16

0·0625

3/16

4·8

64

20

0·27

60

0·80

7/8 in.

7/8

22·23

16

0·0625

7/32

5·6

64

20

0·23

60

0·69

1 in.

1

25·40

16

0·0625

¼

6·4

64

25

0·25

60

0·60

11/8 in.

11/8

28·58

16

0·0625

9/32

7·1

64

30

0·26

70

0·62

1¼ in.

1¼ in.

31·75

16

0·0625

5/16

7·9

64

30

0·24

70

0·56

13/8 in.

13/8

34·93

16

0·0625

11/32

8·7

64

30

0·22

80

0·58

1½ in.

38·10

16

0·0625

3/8

9·5

64

30

0·20

80

0·53

15/8 in.

15/8

41·28

16

0·0625

13/32

10·3

64

35

0·21

90

0·55

1¾ in.

44·45

16

0·0625

7/16

11·1

64

35

0·20

90

0·51

17/8 in.

17/8

47·63

16

0·0625

15/32

11·9

64

40

0·21

100

0·53

2 in.

2

50·80

16

0·0625

½

12·7

64

40

0·20

100

0·50

TABLE 4.—MATERIAL FOR THE WIRE CLOTH OF FINE AND MEDIUM TEST SIEVES.

Class

Designation

Material of wire cloth

Fine Test Sieves

No. 300 to No. 72 inclusive.

Phosphor-bronze.

 " "  "

No. 60 to No. 18 inclusive.

Phosphor-bronze or brass.

 " "  "

No. 16 to No. 5 inclusive.

Phosphor-bronze, brass or mild steel.

Medium Test Sieves.

1/32 in to ½ in. inclusive

Brass or steel.

FRAMES.

5. The frames of test sieves of 12 in. in diameter and under shall be made of brass and those of 18 in. in diameter of brass or bright tinplate. Frames shall be cylindrical in shape. They shall have the dimensions given in Table 5, where the letters " A", " B ", " C " and " D " represent the corresponding dimensions marked in Fig. 2.

The frames of all test sieves shall have an external beading formed around the upper edge. The frames of 8 inch, 12 inch and 18 inch diameter test sieves shall have an internal beading formed around the lower edge. The upper part of the lower beading shall be filled in with a suitable material such as a run of solder to prevent the lodgment on the beading of any material being sieved.

As an alternative to a beading around the lower edge, the frame below the sieving surface may be constructed with brass 18 S.W.G. (0·048 inch) in thickness for 3 inch and 8 inch diameter test sieves and of 16 S.W.G. (0·064 inch) in thickness for 12 inch diameter test sieves. The lower edge of such frames shall be smoothly rounded.

Any fillets or fillings used shall be such that the effective diameter of the sieving surface of any test sieve is not less than the value given for it in Column 8 of Table 5.

MOUNTING.

6. The wire cloth of fine and medium test sieves shall be mounted in the frames so as to be rigid and equally taut in all directions without distortion of the meshes.

The perforated plates of coarse test sieves shall be mounted so that when the sieves are in use the material passes through them in the same direction as that in which the plates were punched.

TABLE 5.—DIMENSIONS OF FRAMES.

1

2

3

4

5

6

7

8

9

10

Class

Mean internal diameter

Mean external diameter

Thickness

Minimum effective diameter of sieving surface

Dept from top edge to sieving surface

Depth from bottom edge to sieving surface

A

A

B

B

C

D

Max. in.

Min. in.

Max. in.

Min. in.

S.W.G.

in.

in.

in.

in.

Fine Test Sieves

3 1/64

3

3

2 63/64

26

0·018

5/8

Fine Test Sives No. 300 to No. 120 inclusive

8 1/32

8

8

7 63/64

26

0·018

7

5/8

Fine Test Sives No. 100 to No. 5 inclusive

8 1/32

8

8

7 63/64

26

0·018

7

2

5/8

Medium Test Sieves

12 1/32

12

12

11 63/64

22

0·028

11

3

5/8

Coarse Test Sieves

12 3/64

12

12

11 31/32

20

0·0392

11

3

5/8

18 3/64

18

18

17 31/32

20

0·0392

17

¾

RECEIVER.

7. A receiver for use with the 3 inch and 8 inch diameter test sieves shall be constructed of the same metal and of the same gauge of metal as the corresponding test sieves and shall be of the same diameter as the upper part of the sieves and of the following depth :

1½ inch for 3 inch test sieves.

2 inch for 8 inch test sieves.

COVER FOR FINE TEST SIEVES.

8. The covers for fine test sieves shall be constructed as shown in Fig. 2. They shall be well fitting and shall be constructed of the same metal and of the same gauge of metal as the corresponding test sieve.

FINISH.

9. Test sieves, receivers and covers shall have smooth surfaces and shall be free from lacquer, japan, or similar finishes. All joints shall be smoothly finished, free from cracks, crevices and projections. In fine and medium test sieves, the crevices above and below the wire cloth at its junction with the frame shall be filled with a suitable material such as a run of solder.

MARKING.

10. All test sieves shall be permanently and legibly marked with :

(a) the words " Irish Test Sieve " followed by the designation.

(b) the nominal width of aperture :

in inches and microns for fine test sieves,

in inches and millimetres for medium test sieves,

and in inches for coarse test sieves.

(c) the manufacturer's name or mark,

(d) the manufacturer's serial number.

Appendix A.

DETERMINATION OF THE WIRE DIAMETER OF THE WIRE CLOTH OF FINE AND MEDIUM TEST SIEVES.

A number of separate fields or areas shall be selected over the surface of the wire cloth of the test sieve. The number of fields shall be as set out for the appropriate test sieve in Column 2 of Tables 6 or 7, and the fields shall be chosen so that no two fields are crossed by the same wire. In each of these fields the diameters of consecutive wires to the number given in Column 3 of Tables 6 or 7 shall be measured in both the warp and the weft directions. The wire diameter shall be determined by the method described in Appendix C, or by an equally suitable method.

Appendix B.

DETERMINATION OF THE APERTURE WIDTH OF FINE AND MEDIUM TEST SIEVES.

A number of separate fields or areas shall be selected over the surface of the wire cloth of the test sieve. The fields shall be chosen so that no two fields are crossed by the same wire. The number of fields shall be as set out for the appropriate test sieve in Column 2 of Tables 6 or 7 and the minimum number of consecutive apertures measured in both the warp and weft directions in each field and in all fields, shall be as set out for the test sieve in Colnums 4 and 5 of Tables 6 or 7. The aperture width shall be determined by the method described in Appendix C, or by an equally suitable method.

TABLE 6.—NUMBER OF FIELDS FOR MEASUREMENT OF FINE TEST SIEVES.

Designation

Number of fields

Number of consecutive wires to be measured

Minimum number of consecutive apertures to be measured in each direction

In each field

In all fields

No.5

10

4

3

30

No.6

10

4

3

30

No.7

10

5

4

40

No.8

10

6

4

40

No.10

10

7

5

50

No.12

10

8

6

60

No.14

10

9

8

80

No.16

10

10

9

90

No.18

10

10

10

100

No.22

10

10

12

120

No.25

10

10

15

150

No.30

10

10

15

150

No.36

10

10

20

200

No.44

10

10

25

250

No.52

10

10

30

300

No.60

10

10

30

300

No.72

15

10

20

300

No.85

15

10

20

300

No. 100

15

10

25

375

No. 120

15

10

25

375

No. 150

15

10

25

375

No. 170

15

10

30

450

No. 200

15

10

30

450

No. 240

15

10

30

450

No. 300

15

10

30

450

TABLE 7.—NUMBER OF FIELDS FOR MEASUREMENT OF MEDIUM TEST SIEVES.

Designation

Number of fields

Number of consecutive wires to be measured

Minimum number of consecutive apertures to be measured in each direction

In each field

In all fields

1/32 in.

10

10

10

100

1/16 in.

10

6

5

50

1/8 in.

10

5

4

40

3/16 in.

6

8

7

42

¼ in.

6

6

5

30

3/8 in.

6

4

3

18

½ in.

6

3

2

12

Appendix C.

MEASUREMENT OF THE WIRE DIAMETER AND APERTURE WIDTH OF THE WIRE CLOTH OF FINE AND MEDIUM TEST SIEVES.

(a) Fine Test Sieves. The surface of the wire cloth of the test sieve shall be covered by a mask which defines the separate field referred to in Appendices A and B, and the number of fields shall be as set out for the appropriate test sieve in Column 2 of Table 6. Mask suitable for producing the required fields are shown in Figs. 3a and 3b.

An optical projection apparatus shall be used for projecting, at a known magnification, undistorted images of the portions of the wire cloth of the test sieve defined by the mask, on to a flat screen. The illumination shall be derived from a bunch filament lamp of at least 100 watt rating and the beam of light from this lamp shall be made closely parallel by mounting the actual source of light at the focus of a condenser of at least 3 in. focal length. The sieve shall be suitably mounted normal to the illuminating beam on a support provided with both vertical and horizontal adjustments so that any portion of the area of the wire cloth of the test sieve can be brought into the beam for examination. The linear magnification of the image on the screen shall be at least 100 times for sieves No. 300 to No. 72 inclusive, and 50 times for sieves No. 60 to No. 5 inclusive. The screen for the reception of the image shall be approximately 5 ft. square and shall be rigidly constructed. The surface shall be either opaque or shall consist of a sheet of plate glass with the side remote from the apparatus suitably ground so as to act as a focusing screen when viewed from the ground side.

An extended focusing arrangement shall be provided to enable the image to be properly focused by the operator whilst standing at the screen. If the focusing is obtained by moving the lens, the extent of this movement shall be restricted to ¼ in.

The required magnification shall be obtained by placing the screen at the correct distance from the projection lens. This distance shall be obtained by mounting a cylinder, whose size is known to an accuracy of 0.0001 in., in the illuminating beam, with its axis truly normal to the optical axis of the projection lens, and adjusting the position of the screen so that the measured width of the image, towards the periphery of the field as well as at the centre, is, according to the lens used, exactly 100 or 50 times the known diameter of the cylinder. This test shall be repeated with the axis of the cylinder turned through90° to ensure that the screen has been set normal to the axis of the beam.

The diameter of the cylinder shall be 3/8 in. approximately when working at a magnification of 50 and ¼ in. for a magnification of 100 and the length of the cylinder shall be about ¾ in.

A specially divided scale as shown in Fig. 4a, shall be used to determine whether the aperture width conforms to the maximum positive tolerance, and the scale shown in Fig. 4b shall be used for the determination of the average aperture width.

(b) Medium Test Sieves. Medium test sieves shall be examined using an apparatus similar to that described above for fine test sieves, but a lens of longer focal length working at a reduced magnification may be used.

GIVEN under the Official Seal of the Minister for Industry and Commerce, this 29th day of November, 1950.

(Signed) JOHN LEYDON,

Secretary,

Department of Industry and Commerce, a person authorised under Section 15 (1) of the Ministers and Secretaries Act, 1924 , to authenticate the Seal of the said Minister.

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