Anthracite Filter Media

Quality Control

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Western Carbons specializes in the processing of anthracite for water filtration and fuel injection. As a major producer of anthracite filter media we can economically produce a large range of gradings as standard. Quality Control has been the key to our success with all the criteria listed below being checked on a regular basis. All production of anthracite filter media is to the European Standard  EN12909 1999, American Standard AWWA B100-01 or  better.

Western Carbons has a documented quality control system. We were awarded ISO status in 1998 which has now been up dated to ISO9001:2000. To maintain our certification we are regularly audited by a registered external body

Quality Control is the most important aspect of filter media production
Customer Requirement	From the order placed by the customer, the grade of filter media may be selected. If it is not a standard grade a target sieve analysis is generated by a specially written computer program so that the resulting product has a size distribution as closely to normal as possible.
Sieve Analysis	A complete sieve analysis is performed on each unit of production. [normally either 1.0 or 1.2 tonne]
Top Size		Upper size of the product
Bottom Size		Lower size of the product
Size Ratio	Maximum 2	Ratio of the top to bottom size
Over Size	Maximum 5%	Percentage retained by the top sized test sieve
Under Size	Maximum 5%	Percentage passing the bottom sized test sieve
Effective Size  d10	.	Theoretical aperture, obtained from the particle distribution curve, that 10% of the particles would pass.
Uniformity Coefficient U = d60/d10	Maximum 1.5	The ratio of the aperture of the sieve which would permit 60% to pass through to the aperture of the sieve which would permit 10% to pass through.
Minimum Size d1	.	Aperture of the sieve which would permit 1% of particles to pass through.
Hydraulic Size	.	Calculated from the Sieve Analysis
Physical Characteristics .		By using the same source of anthracite for all production the physical characteristics of the material may be very closely controlled.
Source	.	Welsh Anthracite
Specific Gravity	1.40 - 1.45	The stated specific gravity of the anthracite is partly dependant on the process by which it has been washed. If it has been washed using a low float specific gravity it will have a lower specific gravity but also a higher carbon and lower ash content.
Bulk Density	c 0.73 kg/litre	Tapped bulk density
Carbon Content	c 90%	Total carbon content
Ash Content	Below 7%	.
Volatile Content	Below 8%	.
Hardness	c 3.5 Moh	This is not a well defined characteristic as only whole numbers are defined on the Moh scale.
Grinding Index	65 Hardgrove	This gives some indication on how well the anthracite will travel but has little meaning in the regard to water treatment.
Compression Modulus	Min 105 bar	Indicates the strength of the anthracite particles against breakage. This requires a special test apparatus [ part of Western Carbons test equipment] and is a characteristic only used by some large companies.
Attrition Loss	.	Below 2.0 % in 100 hours backwashing
Acid Solubility	.	Below 2.0 %  24 hours in 10% HCl
Alkali Solubility	.	Below 2.0 %  24 hours in 10% NaOH