2004 Volume 5 Issue 2 Pages 121-128
Washing and sterilizing a clean room is indispensable for aseptic production, which means that the clean room usually has a wet environment. Optical particle counter (OPC) may be used to maintain and control the aseptic environment. However, an ordinary OPC can only work under low environment humidity, and therefore the environment is monitored in an intermittent manner or the environment monitoring does not start until the concentration of liquid particles in the measurement environment decreases after completion of the washing cycle. Because of these limitations, net production time is shortened, affecting the productivity. In an effort to resolve these issues, we developed a new type OPC system. Using the inertia impact of minute particles, we attempted to design, make and test a measuring system that selectively separated and removed liquid particles that would hamper the ability of the OPC. The resulting OPC system proved to be suitable for particle continuous monitoring even in a wet environment. It has also become clear that particles with 1.0 μm or larger diameters can be precluded from the object of OPC monitoring. Furthermore, it was confirmed that not only micron-size particles, but also sub-micron particles were generated in large quantities during washing and sterilizing processes.
