NIB powder has strong magnetic properties and is easy to agglomerate; so cannot be tested by wet dispersion. The dry dispersion can overcome the agglomeration caused by magnetism through the instantaneous dispersion of high-speed airflow, so it becomes a typical method to measure the particle size distribution of NIB powder.
However, NIB powder is pyrophoric in air. When exposed in air at relatively high temperature, it can ignite spontaneously and destroy dust collecting pipe and filter. Therefore, the particle size analyzer cannot operate normally and it may easily cause significant hazards.
Some precautions can be taken to address this issue:
(1) Use inert gas such as nitrogen instead of 11compressed air as gas source;
(2) Use smooth polyethylene tubes instead of dust collecting pipe to prevent the precipitation
of NIB particles;
(3) Collect samples using water-filtered vacuum collector instead of vacuum bag collector.