COKING VALUE OF TAR AND PITCH: ASTM D4715
EXPLANATION
This test method is used for indicating the relative coke-forming properties and for evaluating and characterizing tars and pitches. This is one of the elements in establishing uniformity of shipments of sources of supply. This test method is applicable to tars and pitches having an ash content not over 0.5 % as determined by Test Method ASTM D2415. Coking values by this method are higher than those obtained by Test Method ASTM D2416.
TEST SUMMARY
A test portion of tar or pitch is heated for a specified time at 1022 +/- 18° F (550 +/- 10° C) in an electric furnace. The percentage of residue is reported as the coking value.
TEST PRECISION
Repeatability: 1.2 % absolute
Reproducibility: 2.3 % absolute
The coking values by this test method are about two percentage points higher than those obtained by Test Method ASTM D2416.
