CTA Report, Draft 1, ISP Review - US Chemical Safety and Hazard ...

The field meter was repositioned to measure field strength following the electrostatic discharge. The
energy of the discharge was calculated by measuring surface potential before and after the discharge.
B.4.2 Dust Ignition Tests
A similar procedure was followed for testing of the powder material to determine its ignitability.
However, the material was screened through a 160-mesh sieve and evenly spread over the plastic sheet
surface before the multipoint corona generator was energized. As the grounding ball was lowered,
observations were made to determine dust flammability. The presence of a flame is the criterion for dust
flammability by propagating brush discharge.
For purposes of laboratory testing, the plastic sheet was used to simulate a condition where sufficient
powder material existed to form an insulating layer. Depending on the specific process, such a condition
may be produced under industrial conditions. RoRo93 (2,26,6-tetramethylpiperdine derivative [a light
stabilizer]), a product of Kuhner A.G., was used as a reference dust for testing.
B.4.3 Test Results
Table B-1 shows the results of the propagating brush discharge ignition tests. The RoRo93 material
readily ignited, but two samples of the SD-52SS black phenolic resin tested did not. As propagating
brush discharges are the most energetic of all types of electrostatic discharges, these tests results show
that static electricity was probably not capable of igniting the phenolic resin dust.
108