Controlled atmosphere oven

An oven for heating a material in a preselected gas atmosphere, comprising:

• a first chamber normally having a first gas therein, said first chamber having an opening for receiving said material therethrough and being adapted to receive said material therein;
• means for sealing said opening in said first chamber after said material is received therethrough;
• a second chamber surrounding said first chamber, said second chamber being adapted to receive said preselected gas therein and said first chamber having at least one gas inlet port therethrough to permit said preselected gas to flow from said second chamber into said first chamber;
• heating means located within said second chamber for heating said first chamber, thereby to heat said material therein;
• means for introducing said preselected gas to said second chamber to thereby displace said first gas from said first chamber, said first chamber having a gas outlet port therethrough to permit said first gas to flow outward therefrom during said displacement thereof by said preselected gas;
• and
• first gas receiving means connected to said first chamber for receiving said first as during said displacement thereof by said preselected gas, said gas outlet port permitting communication between said first chamber and said first gas receiving means, wherein said second chamber comprises an outer chamber and an ante chamber in communication therewith, and the structure being such that said preselected gas is introduced to said ante chamber and said ante chamber surrounds said first gas receiving means, said preselected gas within said ante chamber causing said first gas to condense within said first gas receiving means;
• said means for introducing a preselected gas to said second chamber including a plurality of gas conveying conduits which merge into one conduit feeding said preselected gas into said second chamber, with means for controlling the gas flow through said conduits to increase the flow rate of said preselected gas to said second chamber when purging said first chamber and when cooling said oven and to decrease the flow rate during heating of said material.