English 
An electric drying oven that is heated and kept at a constant temperature under negative pressure is called a vacuum drying oven, hereinafter referred to as a vacuum oven.
There are two types of inner design on the market: round shaped and square shaped. The ultimate vacuum degrees are usually at 1kPa, 0.5kPa, and 0.3 kPa, 0.1kPa, the maximum temperature is divided into 150℃, 200℃, 250℃, the temperature fluctuation is generally ±1℃. Regarding the sealing requirements of the vacuum oven, according to the announcement of the national standard for vacuum boxes GB/T29251-2012, after the ultimate pressure of the working room volume of 0.1 cubic meters and above reaches 0.3kPa, the limit should be maintained for 24 hours at an ambient temperature of 5-35°C. The pressure should not be greater than 8kPa.
For vacuum ovens with a maximum temperature lower than 200°C, the temperature error should not be greater than ±3°C, and the temperature stability within 24 hours should not be greater than 2°C. For vacuum ovens with a maximum temperature exceeding 200°C, the temperature error should not be greater than ±1.5% of the maximum temperature, and the temperature stability within 24 hours should not be greater than 1% of the maximum temperature. The surface temperature of any surface 80mm away from the door frame and observation window of the cabinet and beyond when the set temperature is below 200°C should not be greater than room temperature plus 35°C. The time for the inner tank to rise from 35°C to the highest temperature should not exceed 120 minutes for continuous operation. The time should not be less than 72 hours.
