Aluminum Furnace Maintenance Tips

Play It Safe: Processing Oily Work Without Atmosphere

Coils and other types of work being processed may contain a considerable amount of rolling oil. As the work is heated, this oil is vaporized and will mix with the air in the furnace. When mixed with air (oxygen), this vapor can form an explosive mixture.

To prevent explosion, the oil vapor must be purged from the furnace and replaced with fresh air. A minimum of 4 furnace volumes of purging air are required per hour, but the exact requirement is often larger, and is dependent upon the amount of oil in the load, the nature of the load, and the rate of applying heat.

NFPA (National Fire Protection Agency) recommends that the ventilation rate be sufficient to prevent the exhaust from exceeding 25% of the lower explosive limit (LEL). Guidelines for determining the purge flow rate are given in NFPA 86. NFPA 86 is the operating standard for Ovens and Furnaces. Visit www.nfpa.org for more information.

If the furnace is equipped with an air purge system, the operation and setting of the control valves are noted on the atmosphere piping or air purge piping diagrams.

The latest design, materials and equipment specifications should be obtained from the company before any reliance is placed on the enclosed since changes may occur due to product improvement.