How to Dry Powder in Drying Oven?
There are 2 kinds of drying ovens according to the drying principles: Blast Drying Oven and Vacuum Drying Oven. We can use either of them for powder drying, both drying methods have advantages and disadvantages.
1. We can choose blast drying oven for powder drying, just turn off the blast fan and open the lid of the crucible.
2. We can choose vacuum drying oven, but it is expensive, and if we use vacuum, an extra vacuum should be added, such configuration is much more expensive than blast drying oven.
If we choose blast drying oven for powder drying and turn off the blast fan, 2 factors must be considered:
first, the influence of temperature uniformity to powder drying must be considered.
Second, we can still close the lid of the crucible, but it may affect the drying effect, so if we open the lid, there will still be a breeze circulating over the powder. Such breeze may blow up part of the powder. Here we have the following suggestions of drying powder by a blast drying oven:
(1). Do not dry much powder together, put the powder into different crucibles to increase evaporation area.
(2). We can ask the drying oven manufacturer to configure more drying racks (drying shelves), the racks can not only increase the evaporation area, but also effectively slow down speed of natural breeze, such breeze is formed by the rise of hot air during heating and the decline of cold air, so adding racks can reduce the possibility of powder blowing.
(3).My third suggestion is useful for old drying oven users, we can simply block the blower inlet with baffle, but it is better we shut down the power of the blast fan.
The vacuum drying oven is often used for heat sensitive substances, volatile materials, easily decomposed materials or granular experimental items. The cost of vacuum oven is much higher and we will have to configure a vacuum pump. The vacuum pump will let out some noise, of course we can choose low noise pump, but the cost is higher.
What is the advantage of vacuum drying oven?
Compared with ordinary drying relying on air circulation, powder samples will not be blown or moved by flowing air;
For samples that are not easy to dry, such as powder or other granular samples, the use of vacuum drying method can effectively shorten the drying time;
Vacuum environment greatly reduces the boiling point of the liquid that needs to be expelled, so vacuum drying can be easily applied to heat sensitive substances;
Safer use: under vacuum or inert conditions, completely eliminate the possibility of oxide explosion in case of heat;
Vacuum drying method is used for various mechanical components with complex structures or other porous samples after cleaning, and no residual material is left after complete drying;
The vacuum degree that the vacuum drying oven can reach is 133 Pa. According to the characteristics of the vacuum drying oven, it is widely used in the research and application fields of Biochemistry, chemical pharmacy, medical and health care, agricultural scientific research, environmental protection and so on. It is used for powder drying, baking and all kinds of glassware. It is especially suitable for rapid and efficient drying of dry heat sensitive, easily decomposed, easily oxidized substances and complex components.