What is a desiccator?
Sealable canisters, or cabinets, known as desiccators keep contents dry (and dust-free) with the help of desiccant. These economical storage containers are used for electronics, reagents, optical equipment, electronic parts, PCB boards, reagents and other humidity-sensitive items and are sealed to absorb moisture. Once a moisture-sensitive object is placed inside the desiccator with the desiccant (or drying agent), the object will remain dry or at a set humidity level below ambient on adjustable automatic cabinets. These canisters or cabinets are sometimes referred to as desiccant dryers or desiccant dehumidifiers. Desiccators are important tools for scientists who perform chemical reactions because the units help them ensure accurate chemical measurements before starting a chemical reaction. Desiccators also are used to transport and store samples for short- or long-term.
What are the types of desiccators?
Standard—uses desiccant placed on the bottom of the chamber to remove the moisture. This type of unit is very economical but requires manual monitoring and operation. If the desiccant becomes saturated, it will need regeneration via heating or replacement.
Automatic—offers convenience as it features electric fans and heaters that regenerate the desiccant so manual monitoring is not necessary. These units can be more costly up-front than a standard unit.
Gas purge or cabinets with gas purge port—allows for the flow of dry inert gas, such as nitrogen, to further reduce the humidity level in the cabinet. Ideal for moisture-proof and anti-oxidation storage applications.
Vacuum—employs a vacuum pump to remove air and moisture from all types of materials. Vacuum desiccators help stabilize and preserve samples so they can be analyzed. Usually, vacuum types include a stopcock to enable internal air to evacuate, thus creating lower humidity levels. A separate vacuum pump may be necessary, but some models include a built-in pump. For materials that can be damaged by air and need totally dry storage, the vacuum desiccator is the most secure of the four types.
How to choose a desiccator
Consider the applications, size needed and how many shelves may be required. Round desiccators typically have one shelf while cabinets have several shelves. Choose a desiccator based on its compatibility with the chemicals you will be using. Also look at the plate diameter, flange OD, inside diameter, total height, and clearance above the plate.
From polypropylene to polycarbonate to glass and stainless steel, round or cabinet style, a desiccator is manufactured in various materials and available in a variety of sizes. Today’s plastic desiccators offer the same strength as glass, but at a fraction of the cost and weight.
For a more significant investment, choose a static-free desiccator for instruments that are sensitive to electrostatic discharges. Automatic electronic desiccators automatically remove moisture from desiccant and regenerate it every five hours. Some also offer built-in thermohygrometers. Others can include a nitrogen flowmeter to allow lower humidity levels. Space-saving units take up a smaller footprint for labs that need advanced models without the large dimensions.
Why upgrade a vacuum desiccator?
It may be time to upgrade the old desiccator. Older models may not hold the vacuum as well as newer models. In time, gasket and seals can also wear. Some of the modern desiccators can better isolate from ambient conditions or hold the vacuum longer and include gaskets and seals that don’t need vacuum grease.
