Importance of Humidity Measurement in Environmental Chambers

measuring humidity in chambers

Why is humidity control within environmental chambers so important and yet often so challenging?

Firstly, what is an environmental chamber? In this blog we really mean any close controlled space used for various forms of product testing with specific focus on those test that require humidity control.

Examples include

  1. Environmental chambers or climatic chambers: These are enclosed systems, typically a cabinet or a walk-in room, that can simulate various environmental conditions by controlling factors such as temperature, humidity, pressure, and light.
  2. Stability rooms: Effectively a type of environmental chamber but are used at specific conditions over an extended period.
  3. Controlled environments: Refer to any space or facility where environmental conditions are strictly regulated and maintained. Such as cleanrooms or warehousing for sensitive products
  4. Salt spray, vibration, altitude, vacuum and thermal shock chambers. These are all specialist examples of climatic chambers with additional controlled conditions.
    • a. Salt spray chambers simulate corrosive environments by incorporating a mist or fog of highly saline solution
      b. Vibration chambers simulate several types of vibrations that might affect product durability
      c. Altitude chambers control the chamber pressure simulating low atmospheres or reduced oxygen levels.
      d. Vacuum chambers generate exceptionally low pressures for maritime and aerospace testing
      e. Thermal shock chambers cause very rapid thermal changes using a two-chamber system, these create thermal stress on test items and specifically simulate conditions experienced by product in space.

What are the main applications for environmental chambers

In a general sense environmental chambers of all types are used for the testing, production or storage of products. More specifically they are used for;

  1. Simulation of environmental conditions: By accurately simulate various environmental conditions, such as temperature, humidity, pressure, and light. This enables researchers to study the effects of these factors on products, materials, and biological samples as well as perform calibrations.
  2. Stability testing: long-term storage of products at specific conditions is essential in industries like pharmaceuticals, cosmetics, and food processing. Environmental chambers help assess the shelf life, potency, and safety of products by subjecting them to different environmental conditions over time, ensuring they maintain their quality and efficacy.
  3. Accelerated Aging or Accelerated Life Testing: By subjecting products to extreme conditions, such as elevated temperatures and humidity, these chambers can simulate the long-term effects of aging fast. This helps manufacturers evaluate the durability and performance of their products.

All these use cases and more are often used to achieve regulatory compliance, develop new products or improve existing products and increase product quality.

Regulatory compliance is a particular driver for many industries that must comply with strict regulatory standards and guidelines, such as those set by the FDA (Food and Drug Administration), ICH, and ISO. Environmental chambers and stability rooms enable companies to meet these requirements by providing controlled testing conditions that ensure the quality and safety of their products.

For product development and improvement, environmental chambers enable better understanding of how products and materials respond to various environmental factors, allowing more rapid improvements and optimizations in products, manufacturing processes, and packaging.

What are the challenges with humidity control and monitoring

Controlling and measuring humidity in environmental chambers is a critical aspect of maintaining and monitoring the desired conditions for the many applications we have discussed. Several key issues can arise while attempting to control and measure humidity in these chambers:

  • Sensor accuracy and calibration: Accurate humidity measurement is essential for maintaining the desired conditions within the environmental chamber. However, sensors may drift over time or become less accurate due to contamination or aging. Regular calibration and maintenance of humidity sensors is necessary to ensure accurate measurements. Experience is needed to understand how to reduce downtime during calibration and avoid the negative effects of sensor drift
  • Condensation: When there is a significant difference between the temperature inside and outside the environmental chamber, condensation may form on surfaces, including sensors and other equipment. This can lead to inaccurate measurements and potential damage to the equipment. Probe placement, airflow and chamber control strategies can help to avoid the negative effects of condensation.
  • Temperature-humidity interaction: Temperature and humidity are interdependent variables, and changes in temperature can affect humidity levels. Maintaining stable temperature conditions is crucial for accurate humidity control and measurement.
  • FACT:

    Did you know that at 37°C and 80%rh a ±0.5°C gradient in chamber temperature will cause ±2.5%rh difference!

  • Humidity generation and control: Generating and maintaining a specific humidity level within the chamber can be challenging. Different methods for humidity generation, such as steam injection, ultrasonic humidifiers, or wetted pad systems, have their own limitations and may not be suitable for all applications.
  • Airflow and distribution: uneven airflow within the chamber can lead to uneven distribution of humidity, causing variations in the conditions experienced by different samples and worst-case condensation. Proper airflow design and distribution are necessary to ensure uniform humidity conditions.
  • Contamination: Contaminants like dust, chemicals, or microorganisms can interfere with humidity measurements and control mechanisms, leading to inaccurate readings and unstable conditions. Maintaining cleanliness and proper filtration within the chamber is crucial to minimize contamination, also important is sample preparation as test samples are typically the main source of contamination and volatiles.
  • Response time: Humidity sensors and control systems may have varying response times, which can affect the ability to adjust humidity levels quickly and accurately in the chamber. Selecting the appropriate sensor and control system for the specific application is important to ensure timely and accurate adjustments.
  • Energy consumption: Maintaining specific humidity levels within environmental chambers can consume significant amounts of energy, particularly when heating and cooling systems are required to stabilize temperature conditions. Efficient design, accurate control sensors and energy-saving measures can help reduce energy consumption and associated costs.

How can PST help you to find the perfect measuring solutions for your environmental chambers?

Within Process Sensing Technologies we have a wide range of sensing and monitoring solutions for environmental chambers. More importantly we have a 60-year legacy of working with chamber designers, manufacturers, service companies and end users. So how can we help?

  • Knowledge: Primarily we can help with our depth of knowledge, so much of the support and improvements we achieve with our partners is through collaboration and knowledge sharing which cannot be pinned down in a blog! Sensor mounting locations, filter management, calibration and end-user training are all aspects where we continue to help. We understand the complex issues and measurement science required to get the best performance out of our measurement technologies in these diverse and challenging applications.
  • Advanced sensors: Rotronic humidity and temperature sensors and probes are class-leading for industrial applications offering precise measurement, reliable performance and smart calibration solutions for use in various environments. These probes are essential for maintaining accurate control over the humidity levels within environmental chambers.
  • Transmitters: The Rotronic range of humidity and temperature transmitters ensures they can be easily integrated with new or existing environmental chamber systems. With digital or analog outputs, a range of power supply options, interchangeable digital probes and broad mix of housed, OEM (Original Equipment Manufacturing), customized or kitted solutions these devices can ensure seamless control and monitoring of humidity levels, simple maintenance, low cost of ownership all ensuring that chamber conditions remain stable and consistent for end users.
  • Data logging and monitoring software: Rotronic offers software solutions for real-time FDA-compliant data logging and monitoring of environmental conditions within your chambers. This enables you to track and analyze humidity levels, ensuring that your experiments and tests are conducted under optimal conditions.
  • Calibration and maintenance tools, services and expertise: Regular calibration and maintenance are essential to ensure the accuracy and reliability of your humidity sensors and control systems. Rotronic can provide these services including calibration tools, training or local field servicing all helping you and your end users reduce costs and increase chamber performance.
  • Custom solutions: Specifically for chamber manufacturers we can provide solutions and services to meet your specific requirements for humidity control and monitoring. Specific packing and labelling solutions, hardware modifications and calibration services can all save you time and costs.
  • Complimentary Measurements. Beyond just temperature and humidity, Rotronic and PST offer a range of additional products and solutions from CO2 to Oxygen and Trace moisture. Finally, our Michell dew point sensor range is ubiquitous in the control of larger dryer systems often used in larger environmental chambers.

In our next blog in this series, we will examine some example projects highlighting the challenges and solutions we were able to offer.

Related application notes/blogs

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Related Products

OEM Humidity and Temperature Transmitter - Rotronic XB32A
Humidity and Temperature Probe - Rotronic RMS-HCD-S
Standard Humidity probe - Rotronic HC2A-S,SH
High Temperature Industrial Humidity Probe - Rotronic RMS HCD-IC102

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