Common questions and answers of vacuum oven

Question: why does the vacuum drying box not have the temperature uniformity parameter?
Answer: the general blast drying box is equipped with the temperature uniformity parameter, the natural countercurrent drying box is the working temperature upper limit times 3%, the forced countercurrent drying box is the working temperature upper limit times 2.5%. Only the vacuum drying box does not have temperature uniformity parameters, which is why? Because the vacuum drying box depends on the movement of gas molecules to make the studio temperature uniform is almost impossible. Therefore, conceptually, we can no longer apply the definition of temperature uniformity specified in the usual blast drying box to the vacuum drying box. It also makes no sense to set this index in a vacuum. The amount of thermal radiation is inversely proportional to the square of the distance. The radiation heat received from the 500px of the heating wall is only 1 ≤ 4 from the 250px of the heating wall. There is a big difference. This phenomenon is the same as when you bask in the sun in winter, the sun is warm on the side, and the one you can‘t get on the sun is colder. Because the structure of the vacuum drying box is difficult to make the radiation heat of each point (circular sphere) in the three-dimensional space of the studio uniform and consistent, at the same time, there is also a lack of authoritative evaluation method, which may be the reason why there is no temperature uniformity parameter in the vacuum drying box standard.

Question: why does the vacuum drying box have to be vacuumed before heating?
Answer: the sample is vacuumed in a vacuum box to remove the gas that can be extracted from the workpiece material. If the sample is heated first, the gas expands when it is hot. Because the vacuum box is very sealed, the huge pressure produced by the expansion gas may cause the observation window toughened glass to burst. This is a potential danger. This danger can be avoided by the procedure of pumping vacuum before heating up. If the heated air is pumped out by the vacuum pump, when the heated air is pumped out by the vacuum pump, the heat will inevitably be brought to the vacuum pump, which will lead to the temperature rise of the vacuum pump is too high, which may reduce the efficiency of the vacuum pump. When the heated gas is guided to the vacuum pressure gauge, the vacuum pressure gauge will produce temperature rise. If the temperature rise exceeds the temperature range specified by the vacuum pressure gauge, the indication error of the vacuum pressure gauge may be caused. The correct use should be vacuum before heating. When the rated temperature is reached, if the vacuum is found to have decreased, then appropriate pumping. This is beneficial to prolong the service life of vacuum pump. Customer asked: what is the function of the drying tank of the vacuum drying box? Drying tank is used to absorb water, protect vacuum pump and prolong the service life of vacuum pump.

Question: can the vacuum drying box do more than 250 degrees of high temperature? can 300 degrees do it?
Answer: 250 ℃ is workable; the temperature of 300 ℃ can not be achieved.

Question:  how to control the vacuum degree of vacuum drying box BPZ, what does it mean to achieve vacuum degree?
Answer: according to the experimental requirements, the user can set a vacuum range. When the experimental object is heated to produce water vapor into the air, the vacuum degree must be affected and reduced. When the vacuum range set by the user is exceeded, the equipment automatically starts to vacuum, which has reached the range set by the user.

Question: vacuum drying box, only heating without vacuum can be used? Can it be equated with the use of blast drying boxes?
Answer: no, it will cause temperature deviation to be too large, because it is debugged according to vacuum environment when it leaves the factory.