Silica sand is one of the most common media in gravity and pressure filters. A filter only performs as designed when the media matches the designer’s grading. That makes the size distribution, not a general description such as fine or coarse, the most important part of a filter sand order.
How sand works in a filter
In a granular filter, water passes through a bed of graded media that traps suspended particles. Grain size controls how fine a particle the bed can hold, how quickly head loss builds up and how the bed behaves during backwashing.
Sand is used alone or as one layer in a dual or multimedia filter, with support gravel underneath. Each layer has its own specification, so order filter sand and support gravel as separate items.
Effective size and uniformity coefficient
Filter media is usually specified by effective size (ES) and uniformity coefficient (UC). Effective size is the grain diameter at which 10 percent of the media by weight is finer, written as d10. The uniformity coefficient is the d60 size divided by the d10 size. A UC close to 1 means the grains are closer to the same size.
The AWWA B100 standard for granular filter material lets the purchaser define the size range, including the sizes at which 90, 60 and 10 percent passes and the allowed undersize and oversize. Take ES and UC values from your filter design or the standard your project follows, then ask for a sieve analysis that reports them.
Cleanliness and other properties
Filter sand should be washed so that clay, silt and dust do not cloud the filtered water when the bed is first put into service. Ask how the material is washed and whether a fines limit applies.
Filter media standards can also include properties such as acid solubility and specific gravity. If your specification lists these, include them in the enquiry so the test report covers them.
Working out the quantity
The amount of sand depends on the filter area and the specified bed depth. Calculate the bed volume from your drawings, then convert it to tonnes using the bulk density the supplier confirms for that grade. Allow for handling losses and any media you plan to keep for top up.
If you are replacing media in an existing filter, share the original specification or a sample of the old media with its sieve analysis.
What to send with a filter sand enquiry
Water filtration is one of the applications of our chemical and industrial grade. Share your design values and our team will confirm what can be supplied.
- Filter type and the layer the sand is for
- Effective size, uniformity coefficient and size range
- Any acid solubility, fines or specific gravity limits
- Bed volume or quantity in tonnes
- Packaging, delivery location and PIN code
- Sieve analysis and other test reports required
Explore the relevant grades
Request a silica sand quote with your specification, quantity and delivery location, or contact our team.