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The Difference Between Vacuum Drying Ovens and Blast Drying Ovens

The drying box is also known as the “oven”. As the name implies, the air circulation drying test is performed by electric heating. The drying box is divided into two types: a blast drying box and a vacuum drying box. Drying the blast is to blow out the hot air through the circulating fan to ensure the temperature balance inside the box. The vacuum drying box uses a vacuum pump to pump out the air in the box, so that the atmospheric pressure inside the box is lower than the normal pressure. The vacuum drying oven allows the product to be tested in a very clean state. It is a commonly used instrument used to dry samples and provide the temperature environment required for the experiment.

Drying ovens are used in various industries such as chemical, pharmaceutical, casting, automotive, food, machinery, etc. Drying ovens are generally classified into galvanized steel and stainless steel liners, pointers and digital displays, natural convection and blast circulation, conventional ovens and vacuum types. Below I will give you a detailed description of the difference between vacuum drying ovens and blast drying ovens.

Drying oven

Drying oven

According to the wind cycle, it is divided into natural convection and blast circulation. So there is today’s topic: blast type and vacuum type drying oven, the conventional blast is the blast drying oven, which is often referred to as the drying oven. The dry oven of the wind circulation mode without blasting but natural convection is a vacuum drying oven.

So, where is the detailed difference between the vacuum drying ovens and blast drying ovens? Why do some places use blast drying ovens, and some places use vacuum drying ovens? I will analyze and summarize for you as follows:

  • First, the scope of use and occasions are different.

1. The blast drying oven is heated by electric heating tube. Therefore, it is also called electric blast drying box (hot air sterilization box). It is for colleges and universities, industrial and mining enterprises, hospitals, laboratory, laboratory, research institutes, to drying, baking, melting wax, sterilization, curing, aging, etc. As long as the temperature is suitable, do not dry those flammable, explosive, boiling and other substances, you can use the blast drying oven.

2. The vacuum drying oven is designed for drying heat-sensitive, easily decomposable and easily oxidizable substances. It can flush inert gas into the interior, especially for some complex materials.

Scope of application: Vacuum drying oven is widely used in research fields such as biochemistry, chemical pharmacy, medical and health, agricultural research, environmental protection, etc., for powder drying, baking and disinfection and sterilization of various glass containers. It is especially suitable for fast and efficient drying of heat sensitive, easily decomposable, oxidizable substances and complex ingredients.

Emphasis is placed on dry heat sensitive, easily decomposable and easily oxidizable materials. The blast drying oven cannot be used, only the vacuum drying oven can be used.

the vacuum drying ovens

the vacuum drying ovens

  • Second, the different working principle of vacuum drying ovens and blast drying ovens.

1. The heat cycle of the vacuum drying oven is a natural convection mode inside the oven, and it is not possible to blast. It achieves a uniform heat balance in the oven by natural reflection and radiation of heat. Of course, unlike the forced convection of blast drying, this temperature uniformity is limited, so the vacuum drying oven cannot be like a blast drying oven which has a temperature uniformity indicator.

2. The blast drying oven uses the blast circulation, which generates hot air to take away moisture and small molecular volatiles to produce a drying effect (of course, heating, curing, sterilization and other applications are not for this purpose). Usually there is a positive pressure inside the oven. In order to prevent explosion due to excessive pressure, blast drying ovens usually have balanced pressure relief holes.

  • Third, the difference heating methods between the vacuum drying ovens and blast drying ovens.

1. The blast drying oven is heated by an electric heating tube (of course, there is also infrared heating), and the electric heating tube is generally at the bottom or the rear. The blast drying oven is directly heated and assisted by the exhaust fan. The drying principle is to gradually dry the material by heating the water, solvent or volatile component molecules in the material to make the molecules move quickly to get rid of the dry material. This drying method is fast and the temperature is high. Under the action of the fan, the blast drying oven can quickly remove the volatile substance molecules volatilized from the surface of the material by air exchange to achieve the function of quickly drying the material.

2. The vacuum drying oven is also heated by an electric heating tube, but sometimes it is heated by a partition plate and heated around the box. The principle of the vacuum drying oven is to use a vacuum pump to draw the space where the dry material is located into a negative pressure, that is, a vacuum state. Because the material is under vacuum or low pressure, the boiling point of moisture, solvent and other volatile components in the material is reduced. Therefore, it can be removed from the surface of the material particles by the vacuum pump at a lower temperature.

blast drying ovens

blast drying ovens

  • Fourth, the different attachment of the vacuum drying ovens and blast drying ovens.

1.The blast drying oven can be used after it is powered on.

2.The vacuum drying oven must be connected to an external vacuum pump or a factory vacuum piping system.

Finally, comparison of advantages and disadvantages between blast drying technology and vacuum drying technology.

  • (1) Vacuum drying technology has the following advantages over conventional drying technology:

1. Powdered samples are not blown or moved by flowing air compared to ordinary drying by air circulation.

2. Various structurally complicated mechanical parts or other porous samples are washed and vacuum dried, leaving no residual material after drying.

3. For samples that are not easy to dry, such as powder or other granular samples, vacuum drying can be used to effectively reduce drying time.

4. It is also safer to use, because under vacuum or inert conditions, the possibility of oxide explosion can be completely eliminated.

5. The vacuum environment greatly reduces the boiling point of the liquid to be repelled, so vacuum drying can be easily applied to heat sensitive substances.

6. The vacuum drying oven is specially designed for drying heat sensitive, easily decomposable and easily oxidizable substances. It is filled with inert gas inside, vacuumed and then heated, which is suitable for quick drying of some complicated components. The vacuum drying oven uses an intelligent digital temperature controller for temperature setting, display and control.

  • (2) Compared with the blast drying oven, there are also some short plates.

1. Equipment investment is large and maintenance is troublesome.

2. The vacuum is easy to leak, and the door seal has many problems.

3. Door seals and vacuum tubes are easy to age and need to be replaced regularly.

4. Some vacuum pumps need to be separated from gas and liquid.

drying oven

drying oven

Both the vacuum drying oven and the blast drying oven are drying equipment commonly used in laboratories, but the vacuum drying oven and the blast drying oven have different drying methods and principles. The blast drying oven heats the material under normal pressure to vaporize and evaporate the moisture in the material to remove moisture. However, when the material is heated, it tends to cause adverse reactions such as shrinkage and hardening. Therefore, it is preferable not to use a blast drying oven for drying the heat sensitive material. The vacuum drying oven is a technique for drying at low pressure and low temperature, and is particularly suitable for the dehydration treatment of heat sensitive materials and expensive materials. The difference between the two is that the blast drying oven has one more hot air circulation system than the constant temperature drying oven, which makes the temperature of the oven more uniform at various points.

Therefore, the specific choice of drying oven depends mainly on the products you need to dry, heat or cure.

The above mentioned text is the difference between vacuum drying ovens and blast drying ovens. If you want to know more about this, please contact with the henan lanphan. Henan lanphan is a qualified company, which boasts good reputation both home and abroad. For several years, we are dedicated to the manufacture of laboratory equipment and pipe fittings. If you want to know more more about this or possess the intention to buy it, please contact with us as soon as possible. We are willing to provide you as much information as possible. Our email address is the [email protected]

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