A chamber within a furnace that prevents direct radiation from the heaters striking the workload and can also serve to direct the gasses through the load.
With early gas-fired furnaces, the products of combustion went into the furnace and effectively formed the atmosphere. This was no problem where the materials or components were not in the finished condition. However, for precision heat treatment using controlled atmospheres, mixing the products of combustion with the atmosphere was not permissible. Accordingly, the muffle was originally an inner, gas-tight chamber which segregated the products of combustion and the controlled atmosphere.
Modern gas-fired furnaces enclose the burners in tubes (radiant tubes) to keep the products of combustion separate from the furnace atmosphere. Accordingly, the muffle not only serves to prevent direct radiation from the radiant tubes, which are at a much higher temperature than the workload, but also directs the atmosphere over the radiant tubes and through the load to ensure even heating and atmosphere distribution.
A chamber within a furnace that prevents direct radiation from the heaters striking the workload and can also serve to direct the gasses through the load.
With early gas-fired furnaces, the products of combustion went into the furnace and effectively formed the atmosphere. This was no problem where the materials or components were not in the finished condition. However, for precision heat treatment using controlled atmospheres, mixing the products of combustion with the atmosphere was not permissible. Accordingly, the muffle was originally an inner, gas-tight chamber which segregated the products of combustion and the controlled atmosphere.
Modern gas-fired furnaces enclose the burners in tubes (radiant tubes) to keep the products of combustion separate from the furnace atmosphere. Accordingly, the muffle not only serves to prevent direct radiation from the radiant tubes, which are at a much higher temperature than the workload, but also directs the atmosphere over the radiant tubes and through the load to ensure even heating and atmosphere distribution.
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