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sieves

Sieves are a very ancient tool, at least as old as the open weave baskets used to separate grain from refuse. A later more sophisticated sieve was the medieval miller's bolting cloth. Even more precise sieves began to be made during the Industrial Revolution. In 1800, for example, to extend the supply of grain during an agricultural crisis the king of England forbade the baking of bread with flour that would pass through a sieve with 13 wires on each side of a square inch. (41 George III c 16, 1800)

Many occupations are concerned with the size of large numbers of small objects, such as grain, seeds or soil particles. If a graded series of sieves is available, a batch can be shaken through a stack of sieves with increasingly smaller holes. Weighing the amount left behind in each sieve gives a series of masses which is a size distribution for the particles in the batch. In such situations it is more accurate to describe the sizes of the particles in sieve numbers, rather than as particle diameters. For an example of how sieve numbers are used to grade a commercial product, see abrasives.

The sieves used in industry and the laboratory are precision products. The smaller the particle that is not to pass through the sieve, the finer the wires of the sieve–but despite that, the smaller the proportion of the sieve's area which is hole.

Test sieve apertures ISO (See note 1.)	U.S. Alternate sieve designations, a survival of an older system. Mesh sizes are roughly the number of openings per inch.	Tyler Screen Scale Equivalent Designation
125 mm	5 inches
106 mm	(4.24 inches)
100 mm	4 inches
90 mm	3½ inches
75 mm	3 inches
63 mm	2½ inches
53 mm	2.12 inches
50 mm	2 inches
45 mm	1¾ inches
37.5 mm	1½ inches
31.5 mm	1¼ inches
26.5 mm	1.06 inches
25.00 mm	1 inch	—
19.00 mm	3/4 inch	0.742″
16.00 mm	5/8 inch	0.624″
14.00 mm	(0.53 inch)
13.20 mm
12.50 mm	½ inch	—
11.20 mm	(7/16 inch)
10.00 mm
9.50 mm	3/8 inch	0.371"
9.00 mm
8.00 mm	5/16 inch	2½ mesh
7.10 mm
6.70 mm	(0.265)
6.30 mm	¼ inch	—
Fine Sieves
5.6 mm	#3½ mesh	3½ mesh
5.00 mm
4.75 mm	#4	4
4.50 mm
4.00 mm	#5	5
3.55 mm
3.35 mm	#6	6
3.15 mm
2.80 mm	#7	7
2.50 mm
2.36 mm	#8	8
2.24 mm
2.00 mm	#10	9
1.80 mm
1.70 mm	#12	10
1.60 mm
1.40 mm	#14	12
1.25 mm
1.18 mm	#16	14
1.12 mm
1.00 mm	#18	16
900 µm
850 µm	#20	20
800 µm
710 µm	#25	24
630 µm
600 µm	#30	28
560 µm
500 µm	#35	32
450 µm
425 µm	#40	35
400 µm
355 µm	#45	42
315 µm
300 µm	#50	48
280 µm
250 µm	#60	60
224 µm
212 µm	#70	65
200 µm
180 µm	#80	80
160 µm
150 µm	#100	100
140 µm
125 µm	#120	115
112 µm
106 µm	#140	150
100 µm
90 µm	#170	170
80 µm
75 µm	#200	200
71 µm
63 µm	#230	250
56 µm
53 µm	#270	270
50 µm
45 µm	#325	325
40 µm
38 µm	#400	400
36 µm		—
32 µm	#450	—
28 µm		—
25 µm	#500	500
22 µm		—
20 µm	#635	625
15 µm		800
10 µm		1250
5 µm		2500

Notes:

(1) The ratio between adjacent sizes is the fourth root of 2, so the aperture size doubles every 5th size. Red lettering identifies sizes in common use in the United States that are ASTM supplementary values.

Standards

ASTM E-11.

ANSI Z23.1.

AASHO M92.

Federal Spec. RR-S-366b.

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