Vacuum cleaning apparatus

An industrial vacuum cleaning apparatus for removing gravel and the like from a roof comprising:

• upper container means having an inlet into which particulate materials may be sucked;
• lower container means, communicating through a passageway with said upper container means, into which contaminants may be dumped from the upper container means;
• air pump means for creating a suction in said upper container means;
• pneumatically operated valve means positioned in said passageway between the upper and lower container means for controlling the release of contaminants from the upper container means to the lower container means;
• pneumatically operated valve means connected to the lower container means for releasing collected particulate material therefrom;
• and pneumatic control means for alternatively and intermittently opening the first valve means when the second valve means is closed, and for opening the second valve means when the first valve means is closed, to prevent a significant amount of backflow through the valves into the first container when the air pump means is operating;
• an air suction line leading from said upper container to a water filter unit through which contaminated air from the upper container means may be purified before being exhausted to the atmosphere;
• water hose means leading to said upper container and said water filter means to permit the flow of water from said water filter means to said upper container to wet solids therein;
• and water level maintaining means in said water filter means for removing water from the container, to maintain said predetermined water level.