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November 11, 2021   •   5 minute read

What Are the Leading Functions of a Humidity Chamber?

AES Insights, humidity testing

BHD-202 Test Chamber

Companies across industries utilize testing to not only confirm that their products or components work as intended but also to understand when they fail. 

Often in the real world, heat and humidity lead to failures. That’s why it’s important for manufacturers to create these conditions in a controlled testing environment. Top-of-the-line temperature and humidity chambers enable users to precisely manipulate settings to meet testing standards. You can evaluate the performance of your products and set expectations for consumers. 


How Do Test Chambers Create Your Specified Humidity Conditions? 

As temperature increases, air’s capacity to hold moisture increases as well. That’s what relative humidity (RH) refers to—the level of humidity attainable at a given temperature. An RH at 5 degrees Celsius, for example, is not the same as an RH at 20 degrees. The temperature changes and humidity source must work in concert to reach the desired setting. 

To do that, you need precise control, and test chamber manufacturers accommodate with an advanced vapor generator system. Vapor generators (closed stainless steel or copper tubes) can be customized to fit any chamber. Multiple generators can be used for larger workspaces to increase accuracy as well. Using properly conditioned water (you’ll often see manufacturers add demineralizing cartridges to humidity chambers for this purpose), a heating element produces vapor or steam that mixes with conditioned air in a plenum before entering the workspace. 

Electric sensors provide highly accurate readings to ensure the condition of the workspace meets your requirements. 

This modern system has replaced older methods of creating humidity, such as immersing heaters in water pans or relying on atomizing nozzles (today, you’d find atomizers on salt spray chambers). Standard humidity chambers feature an RH range of 20% to 95%, with dehumidification coils helping the workspace reach lower humidity levels: The coil attracts moisture, which condenses and drains out of the chamber. 

High humidity sensors can be added to reach RH as high as 98%. If you need to create conditions less than 20% RH, you can typically do so in three ways: 

Nitrogen Purge

Because nitrogen gas is naturally dry, it’s slowly added to the workspace to push out the moisture-laden air. Nitrogen also prevents the oxidation of metals and frost from accumulating on the surface of DUTs.

Dry-Air Purge Through Desiccant Air Dryer

In a dry-air purge, external compressed air goes through a desiccant system, which absorbs the moisture, before entering the workspace. 

Recirculating Desiccant Air Dryer

For larger chambers, nitrogen or a standard dry-air purge might prove impractical. As an alternative, the chamber air is circulated through a desiccant then returned to the chamber. Part of the desiccant system, often in the form of a honeycomb wheel, releases captured moisture to the external workspace. 

The relative humidity you need to reach should be a main point of discussion when purchasing a test chamber. You can even use a manufacturer-developed dew point calculator to determine if you'll require optional boosts.  


What Are Some Use Cases for Temperature and Humidity Chambers? 

Humidity is often a key component of highly accelerated life testing (HALT) or highly accelerated stress screening (HASS). The set conditions, determined by the standards you’re testing to, simulate the lifespan of products. In HALT testing, the goal is to find out when products fail over time. A change in conditions corresponds to a specified number of years in a real-world environment. HASS testing, on the other, exposes products to extreme conditions to prove their quality before going to market. 

The results are crucial to setting expectations for customers (in the form of warranties and expiration dates) and ideal conditions: how to ship, store, and operate the product without failure. 

That applies to a number of industries. Electronics companies need to ensure their phones, tablets, and laptops work in a variety of climates (the high humidity of the coasts and the dry, extreme heat of the deserts). The same is true of manufacturers of electric vehicles and airplanes, which, if they malfunction, pose a safety threat. Even packaging plays a crucial role, from choosing the appropriate materials for pharmaceuticals to creating shipping and storage boxes that will protect the contents over time. 

Each industry features its own standards (and companies themselves establish internal criteria as well). Here are some common standards that require a humidity component: 

  • The MIL-STD-810 was developed by the U.S. Department of Defense to evaluate equipment’s performance when exposed to different environmental conditions and identify any weaknesses in the equipment. 
  • RTCA DO-160 uses humidity to determine the thermal expansion in the aviation industry and requires extreme temperature changes. 
  • In the telecommunications industry, GR-1081 specifies test procedures for fiber optics. 
  • The International Standardization Organization (ISO) has published thousands of standards that run the gamut from imaging materials to combustion engines and medical devices. 
  • The International Electrotechnical Commission (IEC) sets testing requirements for electrical, electronic, and related technologies such as power generation, semiconductors, and fiber optics in these industries: batteries, solar energy, nanotechnology, marine energy, and more.
  • The International Safe Transit Association (ISTA) has developed standards for the packaging industry to minimize product damage throughout distribution. 
  • SAE International develops and advances standards for companies in aerospace, commercial vehicles, and automotive engineering. 


These are only a handful of the many standards that include humidity components. Some are specific to industry and country, others are international. That’s why it’s so important to understand your testing requirements prior to purchasing a test chamber and work with a manufacturer who can help you meet them.

Associated Environmental Systems builds custom test chambers to fit your specifications—with optional features such as high humidity sensors and desiccant air dryers, not to mention AESONE CONNECT, a combination of software and hardware that enables remote monitoring—and carries standard temperature and humidity chambers in stock

AES also offers support and service plans throughout the life of its chambers. You’ll test as often as you want, with a leading test chamber manufacturer on your team. Contact us to learn more today. 



You’re looking for a new environmental test chamber, but need some guidance along the way. Consider it done.

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