Typically, we read the temperature from a glass rod thermometer, which reflects the air temperature under normal ambient conditions. However, when placed inside a vacuum chamber, the same thermometer also shows a reading. Can we then claim that this reading represents the actual temperature inside the vacuum chamber? The answer is no. In a vacuum, there is no air, and therefore, there is no air temperature. What the thermometer actually measures is the temperature caused by the absorption of heat radiation. This value depends heavily on the surface characteristics of the thermometer, such as its roughness, and the material's ability to absorb, reflect, and transmit infrared radiation—commonly referred to in infrared engineering as "emissivity." The closer an object’s emissivity is to 1, the more radiant heat it absorbs, and thus the higher its measured temperature. Conversely, lower emissivity means less heat absorption and a lower reading. Therefore, the temperature shown on the glass rod thermometer in a vacuum chamber only reflects the temperature of the thermometer itself after absorbing infrared radiation. It does not represent the actual temperature of the objects or workpieces inside the chamber, especially if those objects have different surface materials with varying emissivity values. This is a crucial distinction when working with vacuum systems, particularly in applications like electric vacuum drying ovens. When using a vacuum drying oven, it’s important to understand that the thermometer reading may not always be reliable. Instead of relying solely on the thermometer, it’s recommended to use your experience, observe the behavior of the materials being dried, and gradually refine your procedures to achieve optimal results. Over time, you’ll develop a better sense of how to interpret the readings and adjust the process accordingly for the best performance and accuracy. Gas Log,Vent Free Gas Fireplace,Gas Log Inserts,Gas Log Sets Yixing Able Ceramic Fibre Products Co., Ltd , https://www.ablegaslogs.com