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September 02, 2021   •   4 minute read

What to Look for in Temperature & Humidity Chambers for Stability Testing

AES Insights, stability chamber

LH-6 chamber next to a snow, fire, and humidity icon

Testing the reliability and durability of your product is an important part of getting it to market. Stability testing, also known as steady-state testing, may be an essential part of effective product testing for you.

In that case, it helps to have a temperature and humidity chamber optimized for this purpose. Here’s what you need to know.

 

Uses of Temperature & Humidity Chambers for Stability Testing

Whether it’s for pharmaceuticals, cosmetics, textiles, food and beverage, or electronics, stability testing is one of the processes companies use to determine how well their products will remain safe and functional while stored on a shelf or in certain environmental conditions. 

There’s hardly an industry that doesn’t need stability testing. While focused on assessing the durability of products, stability testing is also used to evaluate the accompanying packaging as well.  

These products change hands and environments throughout the chain of custody. They should remain safe and protected during shipping, storage, and intended use.

 

How Does Stability Testing Work?

As the name suggests, temperature and humidity chambers rely on a combination of heat and cooling applications and water to imitate conditions within a controlled workspace. Heat is applied to a water source, typically stored in a container attached to the chamber, causing it to become steam, which is then pumped into the air-tight workspace. Temperature-only chambers bypass this humidifying step.

Heated air and steam continue to be fed into the chamber at a steady rate. Depending on the performance level of the chamber, referring to its compressor power, it can take some time for temperatures to ramp up to the levels necessary for a given test. 

These levels are maintained for an extended period of time to assess how well a product or DUT (device under testing) withstands the simulated conditions it will likely encounter once moved to market or in storage somewhere. 

In addition to heating, stability chambers have a cooling feature to imitate colder environments. These testing conditions are achieved by a fan blowing chilled air into the workspace. 

 

Features of the Best Temperature and Humidity Chambers for Stability Testing

It takes time for brands to establish strong reputations with consumers or partners. Those reputations can be deflated overnight if a product fails to perform as expected. This can become a major liability for a company if their product puts consumers at risk or serious danger.

Stability testing is one way to prevent such occurrences. As you look for the best stability testing chamber, here are some features you can expect.

  • Well-tuned temperature reliability resides at the core of steady-state testing. If you can’t be confident humidity and temperatures will remain constant through a test for shelf-life or durability, then you’re wasting valuable time. Effective chambers should feature heating systems equipped with open ceramic-core nichrome heaters that ensure temperature control stays within ±0.5°C.
  • Temperature range within the chamber ought to accommodate testing conditions between -20°C to 94°C (-4°F to 201°F).
  • Humidity capability should range between 20% and 95% RH (real humidity). Some chambers include optional features, such as a high humidity sensor, that extend your humidity range up to 98% RH. On the other end, a desiccant air dryer can be installed to help your chamber reach humidity levels as low as 5% RH.
  • The cooling system in a stability chamber typically consists of a self-contained, compact, mechanical, single-stage refrigeration system. 
  • One of the more recent innovative updates to test chambers is remote monitoring. Stability testing requires many hours for a product or DUT to soak, which can be time-consuming if you need somebody monitoring it in person. Alternatively, remote monitoring technology, like AESONE CONNECT, enables engineers to step away from the lab and still track testing conditions. It can even stop tests as soon as an error is detected. 

 

Further Considerations When Purchasing a Stability Test Chamber

There are just a few more things to keep in mind when buying a temperature and humidity chamber for steady-state testing. 

Size really does matter. If you're testing many products simultaneously or a large product, that will dictate what you'll need in a chamber. 

Look, if you need a walk-in chamber, you need a walk-in chamber. 

Another consideration is the type of testing you anticipate conducting. For example, if you need to stability test in addition to cycling (or an otherwise iterative test), it’s best to invest in a chamber with the power components to change conditions quickly. 

However, if you’re only conducting stability testing then a steady-state chamber is perfect. This is because you're creating conditions and maintaining them. If this is the case, the LH series from Associated Environmental Systems (AES) may be a great option. 

Stability testing requires some patience because it takes time to reach the set conditions. And the nature of the DUT matters—if it gives off heat, a chamber with a smaller compressor will have to work harder to properly condition it.

This is why it’s important to talk to your manufacturer about your specific needs. Does your sample give off a live load (heat) while testing? Does your testing require rapid rise/ramp times? What is the maximum weight to be tested inside the chamber? What is the size and quantity of the device under test? Are you trying to reach a certain standard?

Lastly, the best temperature and humidity chamber for you will match your specific testing standards, which will vary depending on the nature of your product. 

Many factors go into selecting the proper temperature and humidity chamber for stability testing, but this should give you a good framework. A reputable manufacturer will help walk you through your particular circumstances, giving you the assurance your products will remain safe and functioning for consumers for the length of time and conditions intended.

AES is eager to help you identify a temperature and humidity stability chamber that meets your specific needs. Contact AES to learn more about which testing solutions are right for you.

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