Before an automobile or other machinery is repainted, it is generally necessary to remove the old paint. The most efficient way to remove old paint is to sandblast the machinery. Originally, sand was used as the abrasive media. However, sand has a drawback in that it is not generally reusable. Therefore, several artificial abrasive materials have been developed that are reusable. In order to recycle the blasting media, it must be collected and separated from paint chips and other dust and debris. In high volume operations, a dedicated blast room is often provided to serve as the area in which blasting will take place. Rather than requiring the operators to sweep up after every blasting, several blast rooms have either partially or fully grated floors which cover a collection system for collecting the blasting media, as well as any dust and paint particles that are generated during blasting. One conventional collection system uses a multiplicity of tube and hopper sections that are arranged as collection bins that collect the blasting media, as it falls through the grating screen. In full floor systems, the entire floor is covered by the tube and hopper collection system, while in partial systems, a portion of the floor is grated and the operators need only sweep debris on the ungrated portions into the portion of the floor that covers the blasting media collection system. With either arrangement, the tube and hopper sections must be coupled to a vacuum source that sucks the recovered media into a separating chamber.
Tube and hopper collection systems typically include a plurality of spaced apart parallel riser tubes. The riser tubes are independent and each has a multiplicity of funnel shaped hoppers that feed into the tube. The open end of the hoppers face upward and collect the blasting media. The collected materials are channeled into the associated riser tube, which is in communication with the vacuum source.
One problem that frequently occurs with large systems is that it is not cost effective to use a vacuum source that is large enough to simultaneously apply suction to the entire collection system. Therefore, it is desirable to independently apply the vacuum source to particular tube and hopper sections that are sized appropriately for the vacuum source. The entire collection system is cleaned by sequentially applying the vacuum to the various sections.
One prior art attempt to selectively apply a vacuum source to particular sections of the floor recovery system uses a large header at the end of the riser tubes. The vacuum source is coupled to the header. Each riser tube has an actuatable flap that covers its end adjacent the header. The flaps are normally kept in the down position where they cover their associated riser tubes. A controller selectively opens the flaps to sequentially provide suction to the various riser tube sections. Although such a system does allow the use of a substantially smaller vacuum source than would otherwise be necessary, the header arrangement requires a large amount of space, is relatively expensive, and since it has a large number of moving parts in direct contact with the abrasive material, it is relatively prone to failure. Therefore, there is a need for an improved selector mechanism for abrasive material reclamation systems.