Filter Boxes and Filter Pre-Heating Assemblies

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FUSiO2N SL precision pre-cast fused silica filter boxes are providing cast houses around the world with a high quality long lasting product for their molten aluminum filtration systems. FUSiO2N SL is RMG’s high purity, non-wetting fused silica. It has demonstrated longer life than denser fused silica’s because of its smaller grain size, excellent thermal shock resistance, and tremendous non-wetting properties. FUSiO2N SL filter bowls are lower density than traditional filter boxes, giving you less heat loss through the system.



• Low Coefficient Of Thermal Expansion • Excellent Thermal Shock Resistance
• Fine Grain Structure • High Strength
• High Hardness • Long Life And Easy To Clean
• Low Thermal Mass And Conductivity • Minimizes Temperature Loss


Standard sizes are available. Custom sizes and configurations can be designed, engineered, and built to fit your unique casting configuration.

In addition to the precision precast fused silica inserts, complete assemblies can be provided. These include; steel shell, back up insulation kit, precast FUSiO2N SL filter box, inlet and outlet transitions, and can be fitted with an electric or gas pre-heating system and control station. 

The steel shell is fabricated using 3/8” (9mm) steel plate with 100% continuous welds. Combination flanges are used to mate steel assembly sections. They provide ease of assembly as well as hold-fast connections. All flanges use ½” (12mm) steel plate. Hold down plates, made from ¼” (6mm) steel plate, run the full length of the steel shell on both sides. These plates hold the refractory in place, and protect its top surface.

The pre-heating lid is fabricated using 12 GA 304 stainless steel with 100% continuous weld corner supports. It is insulated using compressed 5.00” thick 8 lbs. blanket. The lid is equipped with a 300,000 BTU spark ignited burner or Leister HT 10,000 Hot Air Blowers, enabling quick and efficient pre-heat for the refractory liner, and the filter. This also comes with an over-temp sensor for the refractory, which prevents permanent damage to the bowl, and extends the life of the refractory.

The entire lid system is designed on a center pivot and is lifted out of the way using a pneumatic cylinder and 1/4” (6mm) thick support bracket and lifting arms. The lid is also reinforced to prevent warping from the repeated heating and cooling cycles as well as repeated lifting.

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