Abstract: The air filtration system for a box fan is a frame that couples to a box fan and holds an air filter adjacent to the box fan such that air drawn into the box fan must pass through the air filter. The front of the frame includes a fan mount that retains the fan in the frame using a press-fit. The rear of the frame comprises a filter mount that holds an air filter in the path of air flowing through the fan. The filter mount includes a top door that retains the filter and allow access to install and remove filters. In some embodiments, the air filtration system for a box fan may include a second fan mount to hold a second air filter.

Abstract: The vandal proof knob is designed to protect self-serve car wash station control boxes from costly damage from acts of vandalism or robbery by using a single piece construction of a knob with an elongated shaft that mates with the adjustment shaft of a standard rotary switch. The elongated shaft combined with a separate durable metal bracket mounted inside the control box allows for the rotary switch to be recessed approximately three inches inside the control box offering additional protection against vandalism. The bracket is secured to the control box using at least two fasteners and the rotary switch is also attached to the distal end of the bracket using at least two fasteners. Finally the front face of the knob has position indicating markings made as part of the single piece construction which also provides additional protection against vandalism.