The ceramic foam filter plate is a disposable item, and it is necessary to provide an effective means to seal the filter plate in its proper position in the holder, so as to be easy to assemble, disassemble and clean. The filter chamber itself is usually an integral part of the tank, dumping tray or tundish, etc., and should be made of refractory material resistant to molten metal, similar to the refractory material used in standard tank structures.
Use an elastic sealing device or a gasket-type seal to seal the filter plate in place. The sealing device or gasket-type seal surrounds the filter plate at the beveled portion of the filter plate at the periphery. Gasket-type seals ensure leak-free installation and provide effective separation media, which is essential for easy disassembly.
In addition, since gaskets or sealing devices prevent metal from entering the sealing surface of the filtering unit, their use greatly simplifies cleaning by eliminating the problem of metal corrosion, and effectively extends the life of the unit. In addition, due to its elasticity, the gasket can provide sufficient friction to keep the filter body in place in the filter chamber without the aid of other types of pressing devices. The elastic sealing device should not wet the specific molten metal, resist the resulting chemical attack, and should be fire-resistant enough to withstand higher operating temperatures.
The filter unit is preferably sealed by an edge-type seal along the outer peripheral surface of the filter plate to provide a reliable seal and, together with the gasket, provide the mechanical advantage of keeping the filter in place. If simple press-fitting is not enough to fix the filter in place, naturally various mechanical equipment, such as wedges and compacting weights, can be used.
The oblique angle of the filter chamber and the corresponding oblique angle of the filter plate tend to form a reliable seal and hold the filter in place against the buoyancy force acting on it. Naturally, the gasket or seal should be able to withstand the molten metal used. Typical sealing materials used in aluminum processing include fiber refractory seals of various compositions.