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Spill Pits May Keep You From Being Knee-Deep In Molten Metal
Induction melting furnaces must only be operated with adequate, carefully maintained and dry spill pits. These pits, often called run-out pits, are located under and in front of induction furnaces. They serve to contain any molten metal spilled as a result of accident, run-out or dumping of the furnace in an emergency. Without adequate pits, free-flowing spilled molten metal would flow across the foundry floor, endangering workers, damaging equipment and structures and could also produce devastating fires and explosions. Adequate Capacity- There must be a pit for each furnace large enough to hold 150% of its furnace’s capacity. This size allows room in the pit for the almost inevitable accumulation of metal spilled during routine pouring. Proper Construction- Spill pits must be designed and built by qualified professionals who are experienced in foundry design and knowledgeable about your installation. Pits must be constructed of concrete and lined with firebrick. The area immediately under the furnace must be sloped to carry spilled metal away from the furnace and into a deeper holding pit. The area directly in front of the furnace must be covered with a steel grating. Inverted steel drums set to their full depths in foundry sand in the bottom of the pit aid in containment and later removal of spilled metal. With these drums, the molten metal flows across the sand, melts through the bottoms of the inverted drums and fills them. These can later be removed. Very small furnaces such as Mini-Melt® furnaces, rollover furnaces and smaller Dura-Line® furnaces also require spill pits, but because of the small quantity of molten metal in the furnaces, these ‘pits’ can be surface-mounted structures that will fully contain 150% of the furnace capacity in the event of a run-out. Absolutely Dry- Spill pits must be kept completely dry at all times. This requires careful vigilance since these pits are low points and can catch water from leaks, cleaning operations or ground seepage. Wet pits are bombs waiting to explode! Only dry spill pits can safely contain a run-out or emergency furnace dumping. Furnaces must not be operated if their spill pits are wet! Water Diversion System- A water diversion system, built into your pit during construction or added later, may aid in keeping your pit dry. With this system, an aluminum channel or gutter is placed at the top of the spill pit directly beneath the slope running underneath the furnace. This channel collects any water or liquid running down the slope before it falls into the pit and diverts the water away from the pit to a drain or sump. Attentive Maintenance- As with any key safety system, spill pits must be checked daily. They must be kept clear of debris and flammable materials. Pit covers must be kept clear of slag and other blocking materials that would interfere with the passage of molten metal. Metal from any minor spills must be regularly removed from the spill pits to ensure that adequate capacity is maintained. If you know your spill pit is properly sized, dry and clear of debris, you can operate your furnace with the confidence of knowing that if an emergency occurs, you can dump any molten metal from the furnace into the spill pit.
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