The vacuum Drying Oven is specially designed for drying heat-sensitive, easily decomposed and easily oxidized substances. When working, it can maintain a certain degree of vacuum in the working room and can fill the interior with inert gas, especially for some items with complex components. Fast drying, using intelligent digital temperature regulator for temperature setting, display and control.
Vacuum Drying Ovens can be divided into cubes and cylinders according to the geometry of their working chambers. The ultimate pressure of the vacuum box is generally -0.1MPa, and the pressure indication measurement range of the common vacuum box is generally (-0.1～0)MPa, and every 0.02MPa is a graduation line marked with a number. The maximum operating temperature of the vacuum box can be divided into 150°C, 200°C and 250°C, and other temperature levels are determined by the manufacturer and the user.
Vacuum boxes with different maximum working temperatures have slightly different technical requirements for temperature uniformity: for vacuum boxes with a maximum working temperature ≤200°C, temperature uniformity ≤2°C; for vacuum boxes with a maximum working temperature >200°C, Temperature uniformity ≤ 3 ℃.
For vacuum boxes with different maximum working temperatures, the technical requirements for temperature fluctuation are: for vacuum boxes with a maximum working temperature of ≤200°C, the temperature fluctuation is ≤1°C; for vacuum boxes with a maximum working temperature of >200°C, the temperature The fluctuation limit is ±1°C.
The vacuum gauge equipped with the vacuum box is generally 2.5 grade, and the maximum allowable error of the vacuum gauge at each test point is ±2.5%FS. If there are other grades of vacuum gauges, please refer to them.
What needs to be explained here is that the above indicators are the requirements for the production of vacuum Drying Ovens mentioned in the national standards; but in the actual measurement work, the vacuum Drying Ovens are calibrated, so the above indicators are only used in the calibration work. refer to.
Calibration of Temperature Index of Vacuum Drying Oven
Generally, the volume of the working space of the vacuum box is less than 0.4m3, so the middle layer of the working space is selected as the test plane. The middle layer is a calibration work surface parallel to the bottom surface passing through the geometric center of the studio. The distance between the test point and the inner wall of the studio is not less than 1/10 of the length of each side. The location and quantity of the test points are shown in Figure 1. For vacuum chambers with a working space volume greater than 0.4m3, the number of test points can be appropriately increased to 9 or more, and the location of the test points can refer to the test point locations in JJF1101-2003 "Calibration Specifications for Temperature and Humidity of Environmental Test Equipment" Layout.
According to the above method, arrange the temperature sensor, and after the temperature is stable, you can record the temperature indication value of the vacuum Drying Oven and the standard device to be calibrated, so as to calculate the corresponding temperature deviation, uncertainty and temperature according to the calculation method in the calibration specification. Values for uniformity and temperature fluctuation.
