Corporate Buyers Guide

Inert atmosphere ovens and vacuum ovens are used when oxidation of the sample is a concern. Inert atmosphere ovens typically use either nitrogen or argon to replace air as the atmosphere in the oven. .

Nitrogen is a diatomic molecule that has a very strong bond. This bond is why nitrogen does not react with most chemicals and is a good gas to use in an inert atmosphere oven. It is also very cheap and common; it’s the most common industrial gas.

Argon is a noble gas that is even more inert than nitrogen. It will not form compounds naturally. Argon is the most abundant noble gas and is the most commonly used noble gas in industrial processes. It is usually used in those few cases where nitrogen is too reactive for the process.

Many of the industrial and laboratory ovens present the choice between having gravity convection and forced convection. Both types of convection are used to heat samples in the ovens evenly. Convection is a method of heat transfer that occurs from the motion of a fluid, in ovens the fluid is air.

Natural convection, or gravity or free convection, is convection that occurs when air is heated and the warmer, less dense air rises above the cooler, more dense air. As the warmer air rises, the cooler air sinks and becomes warmer so that it, in turn, rises. This creates a current where the cooler, more dense air sinks, warms up and becomes less dense, rises, and cools and becomes more dense. It is sometimes called gravity convection because without gravity to move the cool, dense air down, the current would not be created.

Forced convection is convection that occurs when air is moved using any type of external source, such as a fan. The warmer air is forced over cooler air by a fan. The fan, or fans, can be set up to provide either a vertical current similar to natural convection or a horizontal current. A few ovens offer a third option, mixed convection. This is a convection current that has both a natural and a forced component. Usually, the fans will blow from the sides, creating a horizontal current, while there is a natural convection current in the center of the oven with a vertical current. Forced convection assures a more even temperature distribution.

Which is right for you? That depends on the amount of material located in the oven and how important the accuracy of the temperature is at every location.