Electrothermal Vacuum Dryer Common Problems and Solutions

The sensor can be placed on the vacuum outside wall. The sensor can accept convection, conduction, and radiant heat simultaneously. The glass rod thermometer in the vacuum chamber can only accept radiant heat, and because the blackness of the glass rod cannot reach 1 and a considerable part of the radiant heat is refracted, the temperature value reflected by the glass rod thermometer is definitely lower than the temperature reading of the instrument. . In general, it is normal that the temperature reading of the meter at 200°C is within 30°C of the reading of the glass rod thermometer. If the temperature sensor of the temperature-control instrument is arranged in a vacuum chamber, the difference between the temperature value of the glass rod thermometer and the temperature reading of the instrument can be appropriately reduced, but it cannot be eliminated, and the sealing reliability of the vacuum chamber increases a possibly unreliable link. . If you do not want to see this difference from the practical point of view of operation, you can use the display correction function unique to the temperature control instrument to solve.

2、The reason why vacuum heating oven is heated first and then heated up again

1) If the heating and air evacuation procedures are followed, the heated air will be pumped by the vacuum pump, and the heat will inevitably be brought to the vacuum pump, which will cause the vacuum pump to rise too high, which may cause the vacuum pump efficiency to drop.

2) The heated gas is directed to a vacuum gauge, which generates a temperature rise. If the temperature rise exceeds the operating temperature range specified by the vacuum gauge, it may cause the vacuum pressure gauge to produce an indication error.

The correct method of use should be vacuumed and heated again. After the rated temperature is reached, if the degree of vacuum is found to have decreased, add it again. This is advantageous for extending the useful life of the equipment.

3) Vacuuming the workpiece into the vacuum box is to extract the gas components that can be pumped out of the workpiece material. If you heat the workpiece first, the gas will expand when exposed to heat. Due to the very good sealing of the vacuum box, the enormous pressure generated by the expanding gas may cause the observation window tempered glass to burst. This is a potential danger. This danger can be avoided by following the procedure of vacuum first and then heating up and heating.

3, the reason why there is no temperature uniformity parameter in the electric vacuum drying oven

The general electric heating (blast) drying box is provided with the temperature uniformity parameter: the natural convection drying oven is the working temperature upper limit multiplied by 3%, and the forced convection drying oven is the working temperature upper limit multiplied by 2.5%. The only reason why the temperature uniformity parameter is not set in the electrothermal vacuum drying oven is why it is almost impossible to achieve the homogeneity of the temperature in the studio by relying on the movement of gas molecules in the vacuum drying oven. Therefore, conceptually, we can no longer use the temperature uniformity defined by a typical electric (blast) drying oven in a vacuum drying oven. Setting this indicator under vacuum is also meaningless. The amount of heat radiation is inversely proportional to the square of the distance. For the same object, the radiant heat received at a distance of 20cm from the heating wall is only 1/4 of the distance from the heating wall. big difference. This phenomenon is very warm when it comes to the sun in the sun and the sun is warm to the sun. Due to the fact that the vacuum drying oven is structurally difficult to make the radiant heat in the three-dimensional space of the studio uniform and uniform, and also lacks an authoritative assessment method, it is possible that the temperature uniformity parameter of the electrothermal vacuum drying oven is not set. s reason.

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