Unit systems consist of small, self-contained dust collectors applied at individual, or conveniently grouped, dust-generation points. The collector units are located close to the process machinery they serve, reducing the need for ducting. Typically, these unit dust-collection systems employ fabric filters for fine dust, with cyclone collectors used for coarse dust applications.
The unit systems benefit from reduced ducting and the resulting reduction of engineering and installation expense. These systems offer reduced operating expense, because some of the units may need to run only intermittently. Each unit can be serviced independently, without the need to shut down the entire dust-collection system.
The unit method requires space adjacent to each dust source. The disposal of dust from each of the unit collectors may require additional dust-handling mechanisms.
The advantages of unit collectors include low space requirements, the return of collected dust to the main material flow, and low initial cost. However, their individual dust-holding capacities, servicing facilities, and maintenance periods are sacrificed to achieve this small size.