Mean Coke Size – the arithmetic mean
size of the coke, determined by hand sizing the coke over a
specified series of screens. Generally, the larger the coke the
better. A narrow size distribution is also desirable.
Japanese Drum Test – a 10kg
representative sample of the +50mm square hole coke is placed in
the specified tumble drum and rotated for 30 revolutions, removed,
screened and replaced in the drum and subjected to a further 150
revolutions. The drum contains lifters that raise the coke and
allow it fall so that it undergoes a large number of impacts with
the drum walls. The test is based on the Japanese Industrial
Standard JIS K2151. A number of indices can be measured. The two
reported in this study are

DI^{30}_{15}– the percentage material
remaining +15mm square hole after 30 revolutions

DI^{150}_{15}– the percentage material
remaining +15mm square hole after 150 revolutions.
For these indices, the larger the number, the
stronger the coke. This test is commonly used in Japan to evaluate
coke strength.
Combined Half Micum / Irsid Test – a
25kg representative sample of the +20mm round hole coke is placed
in the specified tumble drum and rotated for 100 revolutions. The
coke is removed, screened and replaced in the drum and subjected to
a further 400 revolutions in the drum. The test is based on the ISO
556 standard.

 M40
– the percentage material remaining +40mm round hole after
100 revolutions
 M10
– the percentage material –10mm round hole after 100
revolutions
 I20
– the percentage material remaining +20mm round hole after
500 revolutions
 I10
– the percentage material –10mm round hole after 500
revolutions
Larger values of M40 and I20 and smaller values
of M10 and I10 generally indicate strong coke. This test is
commonly used in Europe to evaluate coke strength.
ASTM Tumbler Test – a 10kg
representative sample of the –75mm +50mm square hole coke is
placed in the specified tumble drum and rotated for 1400
revolutions. The test is based on the American standard ASTM D
3402.

Stability – the percentage of coke +25mm after 1400
revolution.
 Hardness
– the percentage of coke +6.3mm after 1400 revolutions
Generally the higher both indices the stronger
the coke. The test is commonly used in North America to evaluate
coke strength.