Filter Media

Graphs

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Specification

The Sieve Analysis of filter media may be represented on
three types of graph. Each graph has its own advantages and
disadvantages.

All the graphs are shown with the resultant curve shown within an envelope. This shows graphically whether or not the media is within specification. Often the envelope and results are represented as a series of straight lines. The American specification AWWA B100 specifically requires a curve to be drawn between the points. This is vital for the true determination of the effective size and uniformity of the filter media.

Standard Graph     [linear]

Advantages        Standard graph paper and computer programs available
Disadvantage     Result is a curve

Log Graph    [log - linear]

Advantages        Not a lot but commonly used
Disadvantage     Result is a curve. Hard to read and measure off results.

Normal Graph    [log - normal]

Advantages        Gives results as straight line. Effective size and
                          Uniformity coefficient may be calculated.
Disadvantage     Special computer program required.