| 摘要 |
An oven 5 is disclosed as having a plurality of chambers 34 which are sealed from the ambient atmosphere, and to which gas, heated to a high temperature outside the chambers, is cirulated via line 13 to each of the chambers for admixture with gas (coming from line 16) which is cool compared to the high temperature gas, to produce in the chambers a mixture of hot and cool gas at a predetermined temperature. The hot gas is circulated to the chambers at a certain desired pressure, and the cool gas is circulated to the chambers at a certain rate of flow. Gas is exhausted from the oven via line 17 also at a fixed rate of flow. The gas pressure in the first chamber 31 to be encountered by an element 6 passing through the oven 5 is monitored at 28 and triggers an adjustment of damper 21 so changing the flow of cool gas when the pressure varies from a desired norm. This change in flow of cool gas influences the temperature which is also monitored at 20. A change in this temperature produces a corresponding change in the mixture of hot and cool gas to return the oven temperature to the desired level. |
