To put things in perspective, the mesh of a screen represents the number of holes found in 1 square inch of that screen. So a screen with a mesh of 200 will have 200 openings per square inch of the screen.
- It should be noted that in general, the higher the mesh size, the smaller the openings will be since the area of measurement does not change.
Typically, we don't really see screens with a mesh larger than 400 since it becomes very difficult to make them smaller. As an example, the holes in a screen with a MeSH 400 are approximately 0.037 millimetres in size.
Expressing the MeSH
The MeSH of a sieve can be expressed in several ways. Either with a + symbol, a - symbol or with a / symbol.
So we can say that a sieve with a mesh size of -325 should not let through particles smaller than a mesh size of 325, which is approximately 0.044 millimetres. On the other hand, a sieve with a mesh size of + 325 will not let through larger particles.
Finally, a sieve with a mesh size of 250 / 325 will capture the impurities located in the presented mesh interval.
The manufacture of screens
It is important to specify that different materials can be used to manufacture the net. Indeed, the type of filament used can have an impact on the filtration capacity since the diameter of these can vary.
In addition, the way the filaments are intertwined will also have an impact on the resistance of the screen and its filtration capacity.