Infiltration of air into atmosphere furnaces
A problem encountered in the operation of the furnace, particularly atmosphere furnaces, is the infiltration of air into the furnace chamber or cooling chamber.
Usually the problem of air being drawn into a furnace is due to the deterioration of radiant tube seals, bearings, door seals, cracked welds, or leaking cooling chambers. One means of determining this in atmosphere furnaces is to pressurize the furnace as tightly as possible and check all bearings, radiant tube ports, door seals, etc., with soap bubbles. One thing that people find hard to imagine is that even though a furnace is operating under pressure, it can still draw air into the chamber. One thing you can be certain of is when a furnace is under pressure and atmosphere is leaking out, this means that air can leak in. Some of the causes of atmospheres or leaks can be as follows: Bearing not properly greased or packing around access plugs or radiant tube plugs or fan plugs has hardened and deteriorated so as not to provide a seal. Another source of air entrance into a furnace is through a cracked radiant tube. When a process problem does occur and it has been determined that the atmosphere gas going to the furnace is good, all the above points should be checked and corrected to cure the problem.