Granulometry

Also known as mesh size, it is the size distribution of sand, gravel, activated carbon, anthracite, zeolite and a wide range of other granular media. The granulometry is normally expressed in the US Standard Sieve test with the aid of a sieve or stack of meshes or sieves.

 

Screening is a method of separating a mixture of grains or particles into two or more size fractions, large materials are trapped above a mesh, while smaller materials can pass through it and be retained by other lower meshes.

 

Meshes or sieves can be used in stacks, to divide the grains into various size fractions and thus determine the particle size distributions. Meshes or sieves are generally used in particle sizes greater than about 50 microns (0.050 mm).

 

Each mesh or sieve is represented by a number that indicates the number of threads crossed for each square inch, for example: mesh number 8 has 8 vertical threads and 8 horizontal threads, forming a grid for each square inch.

 

The granulometries of granular media used in water treatment are expressed in two figures, for example, a activated carbon 8 x 30 mesh or grain size means a range of particles that pass through the number 8 mesh and are retained in the number 30 mesh; this indicates that the particle size or range is 2.38 mm to 0.595 mm.

Conversion table from mesh number (US Standard Sieve) to millimeters and inches

TABLE

Mesh Number
(US STD. Sieve)
Aperture (mm)
Aperture (in)
4

4.76

0.187
5
4.00
0.157
6

3.35

0.132
8

2.38

0.0937
10

2.00

0.0787
12

1.68

0.0661
14

1.41

0.0555
16

1.19

0.0469
18

1.00

0.0394
20

0.841

0.0331
25

0.707

0.0278
30

0.595

0.0234
35

0.500

0.0197
40

0.420

0.0165
45

0.354

0.0139
50

0.297

0.0117
60

0.250

0.0098
70

0.210

0.0083
80

0.177

0.0070
100

0.149

0.0059
200

0.074

0.0029
325

0.044

 0.0017
400

0.037

0.0014

What is effective particle size?

The size of filter media is commonly specified in terms of effective size and coefficient of uniformity, or in terms of particle size range. Effective particle size is defined as the mesh opening through which only 10% (by weight) of a representative sample of filter material passes.

What is the uniformity coefficient?

It is the ratio calculated by dividing the mesh opening through which a 60% passes (by weight) of a representative sample of a filter material, by the mesh opening through which only 10% passes (by weight) of the sample.

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Join the discussion 5 Comments

  • María Isabel Vazzana says:

    si tenemos un producto granular de 20 a 40 micrones, primero cuál es más grande? segundo, es correcto filtrarlo por una malla N° 14? Gracias

    • Carbotecnia says:

      Hola María Isabel,

      La partícula más grande sería el de 40 micras o micrones. Para entender un poco te pongo un ejemplo:
      1 mm equivale a 1000 micrones, la malla 400 tiene una abertura de 0.037 mm es decir, de 37 micrones.
      En tamaños tan pequeños, no se usan las mallas para obtener rangos como el que mencionas de 20 a 40 micras, prácticamente es un polvo muy fino con dificultad para tamizar.
      También puedes revisar el artículo donde hablamos de las micras https://carbotecnia.info/encyclopedia/micras-o-micrajes/
      Espero te sea de utilidad.
      Regards.

  • johanna says:

    Si tengo una hoja de especificaciones tecnicas la siguiente informacion:
    tamano de particula X 10 >= 80 micrones
    tamano de particula X 50 140-300 micrones.
    como interpreto esta infomacion..

    muchas gracias.

  • Daniel Giraldo says:

    ¿Cuál es el tamiz que separa los agregados para el concreto de partículas como limo y
    arcilla?

  • Yackòó Cx says:

    hola carbotecnia, yo trabajo con un equipo de sandblasting y lo que necesito es filtrar las particulas finas y conservar el abrasivo el tamaño del abrasivo es de 210 a 297 micrones el polvo generado claramente seria mas pequeño y es el que necesitaria que pase atraves del filtro,..hay algun proceso o malla que me recomiendes?

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