Sealed forced convection chamber furnaces are suitable if a heat treatment process up to 650°C requires a protective gas atmosphere that does not have to be completely oxygen free. The difference between the two variants is that the I-model only has a sealed outer housing while the SI-model has a welded inner box, which further reduces the residual oxygen concentration.

NA-I design Like forced convection chamber furnaces < 675 l (page 34) with the following changes

• Tmax 450°C and 650°C
• Silicone door seal
• Furnace housing sealed with silicone
• Protective gas connection in the back wall
• Defined application within the constraints of the operating instructions
• Residual oxygen concentration < 1% depending on the volume and type of protective gas
• For non-flammable protective and reaction gases such as argon, nitrogen, and forming gas (national regulations must be considered)

NA-SI design Additional features

• Tmax 650°C
• Welded inner housing
• 2-sided heating and air circulation
• Door sealed with seal gas
• Sealed connection to circulation motor
• Gas inlet via circulator shaft
• Defined application within the constraints of the operating instructions
• Residual oxygen concentration to 0.1% depending on the volume and type of protective gas
• For non-flammable protective and reaction gases such as argon, nitrogen, and forming gas (national regulations must be considered)