Month: May 2022

What are Thermal Cycling Chambers?

May 13, 2022

Thermal cycling testing is designed to enhance the strength, reliability, and quality of products and components. These tests generally require a quick, uniform, and reproducible change in temperature over a set number of cycles according to industry test standards. 

When you need an environmental test chamber with a high rate of temperature change, uniformity, and reproducibility, we recommend referencing your test standards against the dimensions, temperature cycling rate, and overall temperature range of the chamber to determine the best fit.

Below are a few common questions we receive regarding our temperature chambers or thermal cycling chambers.  

1. What temperature change rates are available in a thermal cycling chamber?

Many factors influence the temperature change rate in a thermal cycling chamber. The size of the chamber, the number, weight, and material composition of the samples under test, and the starting and ending temperatures are just a few to consider. 

Generally, temperature change rates of up to 15°C per minute can be produced in a mechanically cooled chamber depending on compressor size and configuration. Adding direct-injected liquid nitrogen supplemental or boost cooling can dramatically reduce cool-down and diminish temperature transition times. 

2. What size thermal cycling chambers are available? 

Like most environmental test chambers, thermal cycling chambers are available in a wide range of sizes. For example, our smallest test chamber has an 8 cu. ft. interior capacity, is equipped with reach-in shelves, and fits through a standard doorway on rolling casters. 

Larger units are available depending on the size and quantity of the test sample. Walk-in or drive-in test chambers, for example, are fully customizable to your exact specifications and requirements. An important consideration to remember, in general, the larger the interior volume of the thermal cycling chamber, the greater capacity of cooling and heating power is required to achieve and maintain rapid temperature transition. 

3. Do you offer humidity with your thermal cycling chambers? 

Some test standards do require a temperature and humidity-controlled environment. Based on your requirements and testing profile, humidity is available within a standard range of 10% to 95% RH. 

It is important to understand temperature and humidity control considerations as they relate to thermal cycling chambers. In general, the warmer the air, the more moisture it can hold within the same volume of space. Therefore it takes significantly more water vapor to elevate the relative humidity of air as it increases in temperature.

The opposite is true as the air cools. Due to this fact, 50% RH at a dry bulb temperature of 85°C is an exponentially higher moisture level than 50% RH at a dry bulb temperature of 10°C.

4. What available options do you recommend? 

Many optional features are available depending on your testing requirements. We typically recommend a few key options based on improving uniformity and reproducibility within a given test.

A compressed dry air purge is helpful to reduce the dew point of the chamber supply air. This protects moisture-sensitive test samples and also reduces condensation during rapid temperature transitions.

Liquid nitrogen boost cooling is a direct injection system used to enhance the temperature cooling rate and produce faster temperature pulldowns. 

A product temperature control thermocouple provides precise temperature measurement and control, directly at the sample. This is especially useful for providing quick temperature recovery during transitions by overshooting the temperature setpoint until the product temperature reaches the desired temperature level. 

5. What types of controllers are available? 

Our most popular and frequently used controller is the Watlow F4T, a proportional-integral-derivative (PID) color touchscreen controller capable of storing up to 40 different profiles. It conveniently offers an ethernet interface for remote monitoring and operation as well as USB ports for download and storage. 

For more robust capabilities, we offer our own russellsOne® color touchscreen controller in a 12” human-machine interface (HMI) format. Data logging is available with up to 64 analog inputs and 4 channels of PID control. With its ability to interface with other software, it is our most frequently retrofitted controller to existing and other test chamber manufacturers’ equipment. 

6. Do I have access to service and technical support after delivery?

We offer an industry-leading parts and service warranty on all our equipment, including our thermal cycling chambers. Purchasing an environmental test chamber is a significant investment. That’s why we’re proud to provide timely, friendly, and economical service to our customers.  

Our dedicated service team is available to meet your needs if and when issues arise. And because we offer a preferred service provider network across our delivery footprint, you’re not handcuffed to one vendor or having to wait for service when your test equipment is down. Whether you call our factory or reach out online, you will receive prompt and effective solutions from our dedicated staff.   

If you have questions or are interested in a thermal cycling chamber, contact us today to begin a conversation.

Combined Environmental Testing – Altitude, Temperature & Humidity

May 2, 2022

Simulating real-world conditions is critical to understanding how products react in a variety of environments. Perhaps no more important conditions exist in which to proactively test products than aerospace and military defense applications. Typically, these products and components must function properly at various altitudes, temperatures, and humidity conditions. Coupled with mechanical or electromagnetic vibration, combined testing is essential to understanding the material resistance to the effects of changing temperature and humidity environments at varying altitudes. 

Why is Combined Environmental Testing Important?

While the individual conditions on their own can be replicated, the importance of combined temperature, altitude, and humidity testing is critical in aerospace, defense, and electronics manufacturing where products and components are functioning in extreme environments. Navigational components of commercial aircraft and guidance systems for defense articles are just a few examples of critical components required to operate functionally in diverse conditions. Combined climatic testing allows manufacturers to replicate these conditions within a controlled environment to test, validate, and diagnose for potential failures in advance of their utilization. 

Most manufacturers utilize combined methods of temperature chambers, altitude testing chambers, and humidity testing chambers for engineering development, operational testing, and qualification. Many requirements involve actively powered devices or parts in operation at altitude including aircraft, missiles, and aerospace components. By synergistically combining environmental conditions, combined climatic testing simulates the effects that are likely to occur over the majority of the deployment life of the test article.

What Environmental Conditions Can Be Created?

To verify products remain operational and durable against the full range of environmental conditions to which they might be exposed, concurrently simulating temperature and altitude or altitude and humidity can help identify potential failures that may not manifest in each condition tested separately. 

MIL-STD-810 G Test Method 520.3 specifically addresses the combined effects of temperature, altitude, humidity, and vibration on airborne electronic and electromechanical components to ensure their safety, integrity, and performance during ground and flight operations. Identifying the specific profile, procedure, and step within MIL-STD-810 G will assist your test chamber manufacturer in designing the equipment to best match your requirements. 

Most altitude test chambers possess the capability to achieve altitude up to 100,000 ft. with extended ranges in some cases to 200,000 ft. The temperature range is typically offered between -70°C and +180°C, with humidity between 10% and 95% RH. Mechanical refrigeration or the use of liquid nitrogen are used to create a wide temperature environment, while rotary vane vacuum pumps of varying sizes create the ‘vacuum’ associated with high altitude conditions. Atmospheric steam generators are typically used to introduce humidity into the system bound within a maximum dry bulb temperature generally not to exceed 85°C. 

Test profiles within military and aerospace standards require the following combined environment testing conditions. Altitude with temperature is produced by cycling 5°C per minute or steady-state temperature testing between site level and 65,000 ft. Temperature and humidity are cycled between 10% and 95% RH typically at site level only. 

What to Look for in a Test Chamber?

While many manufacturers claim to make altitude test chambers, not all are created equal. Consider the following construction factors when determining which altitude chamber manufacturer is best suited for your needs. 

The chamber liner should be constructed of a minimum 16 gauge heavy-duty stainless steel material ensuring robust strength and rustproof quality. Seams should be hermetically sealed to prevent moisture migration during low-temperature operations. Consider external or internal pressure membranes in your selection process. These should be constructed of heavy-duty reinforced welded steel plates to withstand atmospheric pressures induced during testing. 

Additionally, look for a minimum 8” foam glass insulation with a 0.25 k factor to ensure strong temperature uniformity and efficiency. Finally, your manufacturer should offer reliable parts and labor warranty with start-up and service in the field available at request. 

Russells Technical Products has developed a reputation as the industry leader in altitude test chambers, specifically those used for combined temperature, altitude, and humidity testing. There is a reason many of our units are still in operation over thirty years later. Contact us today to learn more about our altitude test chambers and which solution best meets your needs.