Dust Control Handbook for Industrial Minerals Mining and Processing

Figure 9.6. Filtration unit showing lack of maintenance and care (left side) andafter cleaning and the addition of a new intake air filtration unit (right side).Ease of Filter ChangeWhen designing filtration and pressurization systems, one key component is the ease with whichfilters can be replaced when necessary. It defeats the purpose of a good system if a filter to bechanged is so difficult to access that the operator or maintenance workers do not want to take thetime to perform the task. Another consideration is dust contamination during the filter change.The easier a filter is to change, the less contamination should occur to the worker performing thetask and to the work area. When changing a canister filter, a common and effective technique isto remove the new filter from the cardboard box and then insert the old dust-laden filter into thebox, tape it closed, and dispose of it.Uni-Directional DesignThe use of a uni-directional airflow pattern, as shown in Figure 9.7, should be consideredwhenever possible to maximize the air quality at the breathing zone of the operator inside theenclosure. In most systems, both the intake and discharge for the recirculation air are located inthe roof. Unfortunately, this location causes the dust-laden air within the enclosure to be pulleddirectly over the worker as it is drawn into the ventilation system. Further, in many designs, thecontaminated return air and clean filtered air are ducted within inches of each other at the ceiling.This poor design allows for recirculated air to be short-circuited and allows dust-laden return air236 Operator Booths, Control Rooms, and Enclosed Cabs