## Standards for Sieves

**1. Number of Sieves: **

It indicates the number of meshes in a length of 2.54cm in each transverse direction parallel to wires.

**2. Nominal size of aperture: **

The nominal size of aperture indicates the distance between the wires. It represents the length of the side of the square aperture. The I.P has given the nominal mesh aperture size for majority of sieves in nm (or) in mm.

**3. Nominal diameter of the wire: **

Wire mesh sieves are made from the wire having the specified diameter in order to give a suitable aperture size and sufficient strength to avoid distortion of the sieve.

**4. Approximate percentage sieving area: **

It expresses the area of the meshes as a percentage of the total area of the sieve. It depends on the size of the wire used for any particular sieve number. The sieving area kept within the range of 35-40 percent in order to give suitable strength to the sieve.

**5. Tolerance average aperture size: **

A certain amount of variance in the aperture size is unavoidable, and this variation is referred to as the “aperture tolerance average” when represented as a percentage.

Also read: Classification of the grades of powders