8 mesh is a term used to describe the size of granular materials like sand, crushed stone, and mineral aggregates. It refers specifically to the number of openings or wires per linear inch in the sieve or screen used to size and separate particles. In the case of 8 mesh, there are 8 openings per linear inch in the sieve.
Some key questions about 8 mesh include:
What is mesh size?
Mesh size refers to the number of holes or wires per linear inch in a screen or sieve used to separate materials by size. For example, an 8 mesh screen has 8 square openings per linear inch. As the mesh number increases, the size of the openings decreases. An 8 mesh screen will have larger openings than a 10 or 16 mesh screen.
Common mesh sizes
Some common mesh sizes include:
- 4 mesh – Opening size of 4.76 mm
- 8 mesh – Opening size of 2.38 mm
- 10 mesh – Opening size of 2 mm
- 16 mesh – Opening size of 1.19 mm
- 20 mesh – Opening size of 0.841 mm
- 30 mesh – Opening size of 0.595 mm
- 40 mesh – Opening size of 0.417 mm
- 50 mesh – Opening size of 0.297 mm
Mesh vs. microns
Mesh size and microns are both used to measure particle size. However, they represent different units:
- Mesh refers to the number of openings per linear inch in a screen or sieve.
- Microns (micrometers) are an absolute measurement of particle size in metric units.
There is a direct conversion between mesh size and microns. As the mesh number increases, the particle size in microns decreases. An 8 mesh screen has openings of approximately 2380 microns.
How is mesh size used?
Mesh size is commonly used to characterize gravel, sand, crushed stone, and other granular materials that have particle sizes larger than a few microns. Some key applications and uses include:
Sieve analysis
Mesh sizes are used to perform sieve analyses to determine particle size distributions in aggregate materials. A graded series of mesh sizes (e.g. 10, 20, 40, 100 mesh) are stacked and the material is passed through the screens and weighed.
Material specifications
Mesh sizes are often specified for materials like sand and gravel. 8 mesh gravel means gravel that passes through an 8 mesh sieve. 20-40 mesh sand refers to sand particles passing the 20 mesh screen but retained on the 40 mesh screen.
Filtration
Mesh sizes are used to specify the pore sizes of filters. A 40 mesh filter will remove particles larger than ~400 microns.
What are typical 8 mesh particle sizes?
An 8 mesh screen has square openings measuring 2.38 mm per side. Particles of roughly the following sizes will pass through an 8 mesh sieve:
- Gravel: 2.5 mm to 4.75 mm
- Sand: 2 mm to 4 mm
- Granulated materials: 2 mm to 4 mm
Sizes larger than 4.75 mm are generally too large to pass an 8 mesh screen. Sizes smaller than 2 mm will generally pass through an 8 mesh screen.
8 mesh opening size
The actual opening size of an 8 mesh screen is:
- Square openings: 2.38 mm (0.0937 inches) per side
- Diagonal openings: 3.36 mm (0.132 inches)
This means particles with diameters between 2.38 mm and 3.36 mm may pass an 8 mesh screen.
Typical applications of 8 mesh particle sizes
Some typical applications for aggregate materials classified as 8 mesh include:
Drainage gravel
An 8 mesh gravel size (2.5 to 4.75 mm) is suitable for drainage applications, providing high porosity and void space. An 8 mesh size allows water flow while preventing migration of finer materials.
Landscaping gravel
8 mesh gravel sizes are commonly used in landscaping applications like paths and walkways. The 2 to 4 mm particle size provides a stable surface that is comfortable to walk on.
Decorative gravel
An 8 mesh size results in a gravel material with attractive visual texture and appearance for use in decorative landscaping projects.
Aquariums
An 8 mesh gravel size of 2-4 mm is suitable for freshwater aquarium substrate, providing space for beneficial bacteria.
Coarse concrete aggregates
8 mesh gravel meets specifications for coarse aggregate in some concrete mixes. The large 2.5-4.75 mm particle sizes provide strength but reduce shrinkage.
How is 8 mesh size measured and specified?
There are a few common ways that 8 mesh size can be specified:
Mesh number
“8 mesh” simply refers to the mesh number and openings per linear inch in the screen. This directly specifies the nominal particle size range.
Screen sizes
The actual screen opening dimensions may be given in inches or metric. For 8 mesh, common openings are:
- 9.37 inches (2.38 mm)
- 0.0937 inches (2.38 mm)
- 3.36 mm
Particle sizes
A size range may be specified, such as “2.5 to 4.75 mm”, which approximates particles passing through an 8 mesh screen.
Aggregate designations
Standardized aggregate sizes like #8 gravel (2.36 to 4.75 mm) correspond closely to 8 mesh sizes.
Comparisons to other mesh sizes
8 mesh is a relatively large mesh size and is often used for coarse separation. Here is how it compares to other common mesh sizes:
Larger mesh sizes
- 4 mesh – Even larger openings than 8 mesh; allows very coarse particles up to ~5 mm
- 6 mesh – Slightly larger than 8 mesh; openings around 2.8 mm
Smaller mesh sizes
- 10 mesh – Smaller openings (~2 mm) screen out many 8 mesh particles
- 16 mesh – Significantly smaller openings (~1.2 mm) than 8 mesh
- 20-30 mesh – Much finer than 8 mesh; used for fine sand and powders
So 8 mesh represents a relatively coarse separation size versus finer industrial screens.
Conversion table between mesh and microns
The table below shows approximate conversions between mesh size and microns. Keep in mind openings may vary slightly between mesh standards.
| Mesh | Microns |
|---|---|
| 4 | 4760 |
| 6 | 3360 |
| 8 | 2380 |
| 10 | 2000 |
| 16 | 1190 |
| 20 | 841 |
| 30 | 595 |
| 40 | 417 |
| 50 | 297 |
| 100 | 149 |
| 200 | 74 |
This table can be used for quick conversion between mesh number and approximate particle size in microns. Just match the mesh size to determine the corresponding micron size.
Conclusion
In summary, 8 mesh is a commonly used screen size that corresponds to openings or particles of 2.38 mm or ~2400 microns. It represents a relatively coarse size and is often used for gravel, drainage media, landscaping aggregates, aquarium substrate, and concrete aggregates. While particle sizes passing an 8 mesh screen are not precisely controlled, the 8 mesh designation provides a good indication of the approximate size range.
