Filter Sand and Gravel
Red Flint Filter Gravel are naturally- occurring, river-washed,
glacial deposit products.Their excellent chemical properties -
high in silica content and low in soluble calcium, manganese
and iron compound - meet AWWA-B100-89 specifications.
Precision sizing and uniform grading to close limits meet the
rigid spec i fi ca tions of professional engineers throughout the
United States, Canada and overseas.
For over 50 years, Red Flint River sand and gravel have been
satisfying the requirements of industrial and municipal users.
Red Flint products have been specified and used nationally and
internationally because of their high-quality, desirable chemical
properties, color and a wide range of precision sizing.
Processing and regular analysis are supervised by registered
professional engineers. Pre-shipment analysis is available to
be certain of compliance with specifications.
FILTER SAND is graded specifically for use at water filtration
plants. It can be used in municipal, industrial or residential
ap pli ca tions.
The highly spherical shape of UNCRUSHED GRAVEL promotes
good flow and even distribution. Being low in soluble
impurities, it will maintain the quality of the treated water,
especially in softeners. Three inch layers are recommended
in graded support beds.
Physical Properties (Filter Sand):
Color - light tan to reddish brown
Density - 100 lbs./cu. ft.
Effective Size - .45 - .55 mm
Uniformity Coefficient - 1.6 or less
Acid Solubility - 0.3 - 1.6%
Specific Gravity - 2.65 - 2.75
Conditions for Operation (Filter Sand):
Bed Depth - 18 - 30 in.
Backwash Rate - 15 - 20 gpm./sq. ft.
Backwash Bed Expansion - 35% of bed depth
Service Flow Rate
Municipal - 1.5 - 2 gpm/sq. ft.
Industrial - 3 gpm/sq. ft.
Domestic - 5 gpm/sq. ftt.
Highly-spherical shape and uniform grading provides reliable
performance in this product with a long history of
Low soluble impurities prevent undesirable mineral leaching
into process stream.