Abstract: A filter system for protecting a heat exchange coil from corrosive constituents carried by an air stream which is passed through the heat exchange coil includes a flexible filter for removing the corrosive constituents from the air stream prior to its engaging with the coil. A net like spacer is located between the coil and the flexible filter for supporting the flexible filter in a predetermined spaced relationship with the heat exchange coil.

Abstract: A method and a tool for expanding the outside diameter and forming grooves on the inside surface of a tube. The tool comprises an axially extending mandrel, a centering portion, and a grooving portion. The centering and grooving portions of the tool are both secured to the mandrel, with the grooving portion located axially rearward of the centering portion. The centering portion radially projects outward of the mandrel, and the grooving portion is coaxial with and radially projects outward of the central portion of the tool. The central portion defines a smooth annular surface to engage and partially expand the tubes, inside and outside diameters, to guide the tube onto the grooving portion, and to maintain the grooving portion centered within the tube. The grooving portion defines an outside surface to expand the tube further, and preferably includes a plurality of external fins to form grooves on the inside surface of the tube.

Abstract: The present invention is directed to a method and apparatus for joining aluminum members within an aluminum heat exchanger coil. A tubular member to be joined to a separate member in the coil has its exterior surface roughened by sand blasting to enhance adhesive adherence. The roughened surface is covered with a conversion coating to replace any accumulated aluminum oxide, to prevent the formation of additional aluminum oxides and to simultaneously provide a surface adapted to adhere to an adhesive. An adhesive is then applied to the mating areas of the tubular members to be joined and subsequently cured to form a tight secure joint. This invention is particularly useful in field repair of aluminum heat exchanger coils.