Patent ID: 6936108

Claim:
A thermal processing unit comprising: a processing furnace, gas-supplying means that supplies a process gas into the processing furnace, heating means that heats an inside of the processing furnace to a predetermined process-temperature, a normal-pressure gas-discharging system for discharging gas from the processing furnace at a predetermined discharging-pressure that is near to an atmospheric pressure, a first valve provided in the normal-pressure gas-discharging system, the valve being adjustably caused to open and close, a pressure of the gas through the valve being also adjustable, the first valve being able to hermetically shut off, a first pressure sensor that detects a discharging-pressure in the normal-pressure gas-discharging system, a reduced-pressure gas-discharging system for discharging gas from the processing furnace at another predetermined discharging-pressure that is lower than the atmospheric pressure, a second valve provided in the reduced-pressure gas-discharging system, the valve being adjustably caused to open and close, a pressure of the gas through the valve being also adjustable, the second valve being able to hermetically shut off, a second pressure sensor that detects a discharging-pressure in the reduced-pressure gas-discharging system, and a controller that controls the first valve based on the pressure detected by the first pressure sensor and that controls the second valve based on the pressure detected by the second pressure sensor, the normal-pressure gas-discharging system has a bypass pipe that connects to said normal-pressure gas-discharging system at a first position and at a second position along the normal-pressure gas-discharging system and thereby bypasses the first valve thereof, said reduced-pressure gas-discharging system connects to the said normal-pressure gas-discharging system at a position that is between the first position and the second position, and the bypass pipe is provided with a bypass valve and a check valve, and the bypass pipe bypasses a portion of the normal-pressure gas-discharging system located between the first position and the second position, and bypasses the reduced-pressure gas-discharging system.