Explosion-safe Milling System for API

Small Particles and High Safety

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The pharmaceutical manufacturer was required to mill a heat-sensitive product, achieve a particle size of 100 µm, while ensuring a high throughput. In order to prevent the formation of an ignitable mixture during the conveying, dosing, milling and filling processes, the process environment room had to be inerted.

The most important measures employed to prevent explosions in certain areas are to inert the system, monitor oxygen levels, temperature and to regulate nitrogen addition. Having these measures, in place and monitored: a leak could quickly recognized, and the required protective actions could be taken.


In addition to the aforementioned safety precautions, the calculation of the highest allowable oxygen level is paramount. In this case, it was three percent, and this level was programmed as the alarm threshold. If the alarm threshold level were to be reached: the machine would stop in order to prevent a potential explosion. Only if the oxygen concentration returned under the non-critical threshold of three percent the milling process could be continued.


The process is summarily described as follows: The product is conveyed via a vacuum system into an inerted atmosphere. The feed funnel on the Hammerwitt milling system must be continuously coated with the product. The product moves from the inerted feed funnel into the inerted milling chamber where it is milled. The milled material is then removed with a dosing system, and gravity fed into a container where it is precisely weighed, and thereafter packed.