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Macrofiltration is the separation of suspended materials that are visible
to the naked eye, by means of a size selective barrier with an
opening ≥ 5 µm.
There is a wide range of filter types available to meet the various macrofiltration
applications with woven polymeric or stainless steel mesh being among the most popular.
The U.S. Bureau of Standard and American Society of Testing Materials
adopted the following "Sieve Size" specification as a means to standardize
filtration mesh screens. The sieve number is an arbitrary designation and
does not refer to a mesh count/inch.
| Mesh Size | Mesh Opening
(µm) |
| Mesh Size | Mesh Opening
(µm) |
|
| 4 | 4760 |
| 45 | 354 |
| 5 | 4000 | 50 | 297 |
| 6 | 3360 | 60 | 250 |
| 7 | 2830 | 70 | 210 |
| 8 | 2380 | 80 | 177 |
| 10 | 2000 | 100 | 149 |
| 12 | 1680 | 120 | 125 |
| 14 | 1410 | 140 | 105 |
| 16 | 1190 | 170 | 88 |
| 18 | 1000 | 200 | 74 |
| 20 | 841 | 230 | 63 |
| 25 | 707 | 270 | 53 |
| 30 | 545 | 325 | 44 |
| 35 | 500 | 400 | 37 |
| 40 | 420 |
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Mesh Opening is the distance between the strands and is expressed in microns.
Open Area represents the proportion of the total area that is open space and is expressed as a percentage.
Mesh Thickness is the thickness of the woven screen (approximately two strands) and is expressed in microns.
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