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Ultimate Guide to Vacuum Ovens

Views: 987     Author: Site Editor     Publish Time: 2023-09-19      Origin: Site

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The vacuum oven provides efficient drying capabilities to ensure the integrity of sensitive materials. Whether you are an experienced researcher or a beginner, understanding the key factors to consider will guide you in making an informed decision.

Vacuum ovens are one of the must-have instruments in the laboratory, with a variety of uses, including drying, sterilizing, and annealing. It is undoubtedly a very profitable investment for a laboratory. Learn more about the 

uses, benefits, and considerations when choosing a vacuum oven.

What is a vacuum oven


A vacuum oven is a device that accelerates the drying of objects using vacuum and heat. During the drying process, the vacuum oven is filled with inert gases such as helium and nitrogen so that the contents do not oxidize. Moreover, the pressure inside the chamber is reduced during the drying process, which enables the vacuum drying oven to remove moisture from the contents at a lower temperature.

Some of the features of a vacuum oven are as follows:

  1. Reduce the moisture and oxygen in the chamber to improve the drying efficiency

  2. Lowering the boiling point of the solvent, thus reducing the heating temperature.

  3. The chamber is filled with inert gas, which greatly reduces the oxidation of the contents and is very suitable for processing flammable and explosive substances

  4. Moisture can be discharged through the exhaust port, accelerating drying

Drying methods of the vaccum drying oven

The drying principle is to convert liquid water into vapors and then transfer the vapors out to achieve drying.

  1. Heating: This is one of the most common drying methods, in which the water inside an object is vaporized by heating it. Water is quickly excited into vapor at 100℃.

  2. Air drying: When it is impossible to heat to a certain temperature, it can utilize air drying. The dryness of the air affects the drying effect. It works on the principle that when there is insufficient heat, the boiling point of water is lowered by pressure changes. The water evaporation process will cause the contents to heat up, and the greater the temperature difference between the air and the surface of the dried material, the faster the drying speed will be.

  3. Vacuum drying: If the above two methods can not meet your drying needs, you can choose vacuum drying.

When vacuum drying, the surface temperature of the object to be dried needs to be kept close. If the temperature is too high, the object may be damaged; if it is too low, it cannot turn the water into water vapor.

Vacuum drying ovens add more heat, removing the vapors quickly. At the same time, air is introduced to flow in the right direction to maintain the temperature during drying. Vacuum drying creates a low-pressure environment and then quickly removes the excess water vapor from the material's surface. This is one of the fastest drying methods available.

What are vacuum ovens used for

What other functions do you know about Vacuum ovens? In fact, besides drying, you can also use it for dehumidifying, antioxidantizing, annealing, etc. The versatility of the vacuum oven is one of the most important reasons why it is a must-have lab instrument. Below are some of the most common functions of a Vacuum oven:


Drying and dehumidification are two of its main functions, commonly used for temperature-sensitive or fragile objects. Especially for porous objects, vacuum drying removes moisture from the pores. The dehumidification process of the vacuum oven is very gentle and does not potentially damage the product.

The air pressure inside the chamber is low to remove moisture at low temperatures. This is very favorable for microchips or medical devices. Generally, these parts are vacuum dehumidified after production.


This is a feature that many people need to be made aware of. The exhaust function of a vacuum oven plays a vital role in removing chemical residue or moisture from parts. The common ASTM E595 standard has standard requirements for vacuum degassing.

Baking utilizes an increased temperature inside the vacuum oven to evaporate chemicals from the object. Using a vacuum oven allows for safer and more effective removal of chemicals.

Preventing oxidation

A vacuum drying oven is commonly used in the pharmaceutical industry to prevent oxidation of drugs. It can quickly and effectively prevent the product's oxidation, scaling and corrosion and ensure its quality.

Compared to other types of laboratory ovens, vacuum drying ovens allow for better control of the drying progress in the chamber and more intuitive adjustment of variables in the drying process.


Annealing uses high temperatures to change materials' chemical and physical properties, such as their hardness and flexibility.

Vacuum ovens are ideal for annealing materials. Not only does it prevent decarburization and surface oxidation, but the surface of the annealed material is clean and requires no cleaning.

Application of vacuum oven

Medical Equipment

You may wonder why medical equipment needs to be placed in a vacuum oven. The most fundamental purpose is to sterilize it. Some medical equipment is very delicate and needs to be sterile when in use. Vacuum ovens can remove bacteria, fungi, pathogens, etc., that adhere to the instruments. They also do not damage heat-sensitive materials. Many experts recommend choosing vacuum drying ovens for sterilizing medical equipment.

Electronic Products

This may make more people wonder, do electronic products also need to be sterilized by vacuum ovens? No. Vacuum ovens are used in electronics to remove moisture from precision parts or PCBs. We all know that moisture accelerates the corrosion of metal parts, which can lead to damage. Dehumidifying components after production can effectively extend the service life of the details. And for watches, cell phones, etc., that fall into or get into the water, you can use a vacuum drying oven for quick drying treatment.

Aerospace Manufacturing

Yes, vacuum ovens are also used in aerospace manufacturing, where many satellite parts need to be kept in a vacuum to ensure they work properly. That's why we choose to use large vacuum ovens to test them after production is complete. This step plays a crucial role in the normal operation of the equipment in the future.

Food Industry

The food industry uses vacuum ovens to remove moisture from food products to extend their shelf life. It can also be sterilized and smoked, which helps improve the food's shelf life and taste.

Advantage of lab vacuum oven

Lab vacuum oven has many advantages, which are briefly listed next:

  1. Low boiling point, suitable for drying temperature-sensitive or inappropriate materials.

  2. Can complete the drying in a short time, improving the efficiency.

  3. Can dry particles or powder material and will not be blown away

  4. No harmful substances are produced during the drying process

  5. The principle of operation is more energy-efficient

  6. No thermal explosion

How vacuum oven works

Before understanding how a lab vacuum oven works, let's first understand the core components of a vacuum oven:

  1. Vacuum Controller: The main role is to control the pressure in the chamber more stably and accurately, avoiding sudden airflow change.

  2. Condensate: Effectively recycles the steam or harmful gases generated during drying. It prevents the vapor from re-entering the vacuum pump or controller.

  3. Vacuum Pump: As the core part of a vacuum oven, the main role of a vacuum pump is to extract the gas inside the oven, thus creating a vacuum environment. The main working principle is to lower the boiling point of a substance by lowering the pressure so that the liquid can evaporate at a lower temperature. It operates on the principle of using a vacuum to reduce the pressure inside the chamber to more than the vapor pressure of the liquid, thus allowing the liquid to boil.

You can operate the vacuum oven by following the steps below:

  1. Start the vacuum pump to pump out the air in the cavity

  2. When the pressure is reduced to a certain standard, turn off the vacuum pump.

  3. Pneumatically heat the oven to raise the temperature in the chamber to the boiling point of the liquid

  4. When the temperature and time heating to a certain degree, close the heater

  5. Turn on the vacuum pump to re-inject air into the furnace

  6. Remove the item after cooling

How to choose a vacuum oven

VO-90PI & VO-90P

Vacuum oven has many uses, such as incubation, drying and sterilization. If you want to choose a suitable vacuum oven, you can use the following points as the selection criteria.


Make sure the Vacuum oven can reach the highest temperature you need. The common ones are +10~200℃, +10~250℃, and some special ones can reach 350℃. Choose a suitable temperature according to your needs before purchasing. Do a temperature test before use to ensure it can work more accurately and evenly. (Temperature uniformity greatly impacts the inward test results, so make sure the temperature uniformity inside the chamber is consistent before purchasing).


Good gravity convection ensures that good air circulation is maintained in the chamber. In conjunction with a fan, it is possible to actively distribute air into the vacuum chamber for even heating.


The size of the chamber determines the maximum volume of the object to be dried at any one time. For sellers who need to dry large objects, it is important to know the chamber size of the Vacuum Oven before purchasing.


Before purchasing, ensure that the power supply's capacity and configuration meet your laboratory's standards.

Recovery time

Frequent oven door opening during use places an additional burden on the drying process and requires compensation for heat loss. The idea is to have the vacuum oven recover its temperature quickly. If your experimental specifications or requirements require a high degree of temperature accuracy or consistency, supporting a short recovery time for your results is important.


If your purchasing budget is low, a vacuum oven made of galvanized material is economical. Also, controllers, heating elements, and thermostats need to work frequently, so try to choose high quality before purchasing to get a longer service life.


Many vacuum ovens come with automatic diagnostics, calibration and logging features, which ensure that your experiments are more accurate.


What size vacuum oven do I need?

This is one of the important selection factors when choosing a VACUUM OVEN, so how do I choose? It can be considered from the following points:

Sample size: Considering the sample size to be placed each time is the most important reference standard for choosing a vacuum oven. If the shape of the sample is not regular, you need to estimate the maximum size. It is also recommended that you purchase a vacuum oven that is 1.5 times larger than your needs for the first time.

Placement space: Evaluate the maximum space that can reserve in your lab. Make sure that you can safely place the vacuum oven in a space.

Budget: Lab vacuum ovens with higher capacity are generally more expensive. Evaluate your budget and balance it with your needs.

What temperature range does a vacuum oven need to maintain

Lab vacuum ovens all have a temperature range of 10-200/250°C.

Low temperature range: 20℃ - 100℃ (for temperature sensitive materials)

Medium temperature range: 10°C - 150°C (for most drying applications)

High Temperature Range: 10°C - 200°C (for materials that require high temperatures to achieve the desired results)

Ultra High Temperature: 10°C - 250°C (specific to certain industries and applications)

How to choose the vacuum degree of the vacuum drying oven?

The vacuum level that a vacuum drying oven needs to achieve depends on the material to be dried and the specific requirements of the drying process. As mentioned, vacuum drying ovens can have different vacuum pressure ranges, usually measured in millibars (mbar) or torr. The appropriate vacuum level depends on factors such as the solvent's boiling point or the material's moisture content. The specific vacuum pressure will vary depending on the material to be dried and the desired drying conditions.

In many laboratory and industrial applications, vacuum drying ovens can achieve vacuum pressures in the following ranges:

1. Low vacuum: 200 to 400 millibars (mbar) or 150 to 300 torr.

2. Medium vacuum: 10 to 100 millibars (mbar) or 10 to 75 torr.

3. High vacuum: 0.1 to 10 mbar or 0.1 to 7.5 torr.

What types of materials can be dried in a vacuum drying oven?

  1. Thermal-sensitive materials: microorganisms, fruits, enzymes, vegetables, antibiotics and other sensitive materials that are sensitive to temperature and may degrade or lose efficacy under high temperatures.

  2. Powder: Vacuum oven can effectively dry granules or powders, and the items remain intact after drying is completed

  3. Flammable and explosive substances: Only lab vacuum ovens certified for explosion protection, according to ATEX, IECEx, or Hazloc, can handle flammable and explosive substances.

  4. Organic solvents: Organic solvents are effectively prevented from evaporating during drying.

  5. Pharmaceuticals: Pharmaceuticals containing Active Pharmaceutical Ingredients (APIs) can have their water content removed using a vacuum oven to ensure their integrity.

  6. Measuring cups: Measuring cups in the laboratory need to have completely dry surfaces, which has a critical impact on the precision and accuracy of the results.

  7. Electronic components: to remove water and prevent potential damage during further processing or assembly.

  8. Food: Vacuum drying ovens are used to dry fruits, vegetables, herbs and other food products while retaining their color, flavor and nutrients.

  9. Chemicals: a wide range of chemicals, reagents and chemical mixtures.

Not all materials are suitable for vacuum drying, especially those that may react under reduced pressure or require specific drying conditions that cannot achieve in a vacuum environment. The compatibility of the material with vacuum drying needs to be verified in advance before drying.

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