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Clack Garnet is a high hardness, high density granular filter media. It is normally used
as the lower (final) filtration of a multi-media bed down flow filtration system.
Garnet
Called multi-media or mixed media filtration, the
high density, small grain size of Clack #30-40 Garnet solves a major filtration problem.
In a single media granular filter such as a sand filter, the material will hydraulically
classify during backwash according to granule size, the smallest rising to the top. When
water
flows downward through the sand, the fine particles at the top of the bed do most of the
straining of the sediment. The solids form a cake on the surface with
filtration typically taking place in the top few inches. As the cake forms, the filtration
becomes finer and the head loss increases exponentially with time.
The ideal situation would be to have the large
grains of media at the top to trap the large solids, and a uniformly decreasing grain size
in the direction of fluid flow with the small grains at the bottom to do the final
polishing. The penetration of the solids into the entire bed allows for increased solids
storage, longer filter runs, and higher filtration rates.
A properly designed multi-media system will
maintain its unique grading of large grains on top and small grains on the bottom and
provide superior performance even after many backwashings. This stable condition of large
grains above finer ones is achieved by the use of materials of different sizes and
specific gravities. Garnet with its high specific gravity of 4.0 forms the lower fine
grain layer, its 0.3 mm effective size can filter down to the 10-20 micron range. Filter
Sand, (effective size of 0.5 mm) and Anthracite, (effective size of 0.9 mm), or Filter-Ag®
can form the larger, less dense layers.
Multi-media filtration technology is applicable
to both water and waste water treatment. Custom designed filters with varying filter bed
configurations can be designed to meet specific needs. For the majority of municipal and
industrial water supply applications, a filter bed composed of 55% low density material,
30% medium density material, and 15% high density material is recommended.
#8 Garnet at 140 lb/ ft³ is a good choice for
support beds when using other high density filtration media such as high purity Corosex II
or the new manganese dioxide oxidation medias such as Pyrolox.
ADVANTAGES
High specific gravity allows unique filter design
In combination with other filter medias, higher flow rates, higher loading and
better
filtration can be achieved
High hardness reduces attrition and provides for years of reliable service
An excellent support bed for other high density medias
Clack garnet meets AWWA B100-96 specifications.
PHYSICAL PROPERTIES
Color: Light tan to reddish purple
Type: Almandite
Crystal System: Cubic
Hardness: 7.0-7.5 (Mohs scale)
Bulk Density:
#8 Garnet: 140 lbs./cu. ft.
#8-12 Garnet: 140 lbs./cu. ft.
#30-40 Garnet: 130 lbs./cu. ft.
Effective Size:
#8 Garnet: 2.0 mm
#8-12 Garnet: 1.5 mm
#30-40 Garnet: 0.35 mm
Uniformity Coefficienty:
#8 Garnet: 1.3
#8-12 Garnet: <1.5
#30-40 Garnet: 1.4
Specific Gravity: 3.8-4.2 gm/cc
Free Silica: Minimal
Acid Solubility: Minimal
CONDITIONS FOR OPERATION
Wide range - application specific |


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Drinking Water Treatment System
Components Classified by
Underwriters Laboratories Inc.® in
Accordance with Standard
ANSI/NSF 61-(1991)-57Y3 |

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The information and recommendations in this publication are based on data
we believe to be reliable. They are offered in good faith, but do not imply any warranty
or performance guarantee, as conditions and methods of use of our products are beyond our
control. As such, Clack makes no express or implied warranties of any kind with respect to
this product, including but not limited to any implied warranty of merchantability or
fitness for a particular purpose. We recommend that the user determine whether the
products and the information given are appropriate, and the suitability and performance of
our products are appropriate, by testing with its own equipment.
The information and recommendations given in this publication should not be
understood as recommending the use of our products in violation of any patent or as a
license to use any patents of the Clack Corporation.
The filter medias listed in this brochure do not remove or kill bacteria. Do not use with
water that is microbiologically unsafe or of unknown quality without adequate disinfection
before or after the system.
Clack will not be liable under any circumstance for consequential or
incidental damages, including but not
limited to, lost profits resulting from the use of our products.
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