Sieve , Official Standards of Powders .

Official standards for Powders

Grade of Powder	Sieve through which all particle must pass	Sieve through which not more then 40% of particles
Coarse	10	44
Moderately coarse	22	60
Moderately fine	44	85
Fine	85	Not Specified
Very Fine	120	Not Specified

Sieve :

1. Number of sieve :

the number of meshes in a length of 2.54 cm ( 1 inch ) , in Each Direction , Parallel to the Wire .

2. Nominal Size of Aperture ( hole ):

the distance between the wires , so that it represents the length of the side of the square aperture .

3. Nominal diameter of the wire :

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

4. Approximate percentage sieving area :

area of the meshes as a percentage of the total area of the sieve . it depends on the size of the wire it should be 35 - 40 % .

5. Aperture tolerance average size :

some variation in the aperture is unavoidable . Limits are given in I.P. Aperture tolerance average is lower for coarse sieves then the fine sieves .

Perforated Plate Sieve : 

1. sieve may also be made by drilling in metal plate .

2. this type of sieve will have circular aperture as against the square aperture of the wire mesh sieve .

3. in general these sieves are used in the large sizes and can be made with greater accuracy than wire mesh sieves .

4. They are less susceptible to distortion in use  .

I.P. Specification of sieve :

Number of Sieves	nominal size of the aperture(mm)	nominal diameter of the wire (mm)	Approximate percentage sieving Area(%)	Aperture tolerance average size(%)
6	3.812	1.422	44	3.2
8	2.057	1.118	42	3.3
10	1.616	0.864	44	3.3
22	0.699	0.457	36	4.0
25	0.599	0.417	35	4.2
30	0.500	0.355	35	4.4
36	0.422	0.284	36	4.9
44	0.353	0.224	38	4.8
60	0.251	0.173	35	5.3
85	0.178	0.122	35	5.9
100	0.152	0.102	35	6.2
200	0.076	0.051	36	8.2