Sometimes it's a good idea to look back. I was interested in seeing where our industry was 5 years ago on the topic of mist collection. This was a time when the topic was really hot, and just ahead of the newest regulations in Southern California. I located this article from Cutting Tool Engineering related to the Donaldson products. I personally have installed two Donaldson systems myself. The first was for separating carbide grinding fines from the metalworking fluid in Southern California. The system worked great, but what I remember most was the vibratory feeder. It must have been making shaking at just the right frequency because those So. Cal. bees thought it was the mother of all queens singing her love song. From across the shop we couldn't always see the bees, but whenever the grinder would run away from his machine wildly waving his arms, we knew they were back. The second Donaldson system I installed was a central Torit dust collector for capturing machined graphite fines. Before I installed this system, no rock bit manufacturer had one. All the shops were filthy and you had to hire people with exceptional balance because the place was a slippery as an ice rink. I was just smart enough to let the Donaldson guy provide the calculations and to follow his advice. It worked great. Within two years, everybody had one. This article discusses the pros and cons of central systems when trying to capture metalworking fluid mist, and provides a nice analysis of issues and calculation basics. Originally published in Cutting Tool Engineering.