How a Conductivity Meter Works to Help Master Thermal Stress without Cracking & Leakage

Thermal stress due to temperature change is an everyday challenge when it comes to CIP and SIP (Cleaning in Place & Sanitise in Place) cleaning processes. In this article, PIF speaks to leading sensor and measurement device specialists, Baumer to find out how a conductivity meter works to resolve thermal stress within these cleaning processes and how this can benefit the food and beverage industry.

During CIP and SIP cleaning processes, temperatures swing between 0°C at ice water stage, through to approximately 150°C at sterilisation. These temperature swings from freezing to high-temperature levels can place stress on the materials used. This is known as thermal stress. Failure to deal with this appropriately, it can lead to cracking and leakage. It is therefore vital that the components in use during the cleaning processes have the capability to withstand fluctuating temperatures.

Why is temperature control important in food safety?

Firstly, it is important to understand why temperature is an important factor within cleaning processes for food safety and hygiene. This is largely due to the knowledge that heat can kill bacteria. However, the high temperatures in use during  CIP and SIP processes cause long-term stress to the environment, equipment, and materials.

The challenges for the operator when deciding on their sanitisation processes is that although they ensure food safety by clean, sterilised equipment, there is also the cost, time, and efficiency of the processes to consider. For example, the service life of the equipment in use during the cleaning processes can be negatively affected by thermal stress. How a conductivity meter works can provide an efficient solution.

How a conductivity meter works to resolve thermal stress?

Within CIP and SIP processes,  conductivity meter's are used is to measure the concentration of acid and caustic. This is in order to achieve the maximum cleaning effect. It can also serve as a media detection and separation application. This is useful to reduce the wastage of already used liquids by collecting them for use during another cycle.

The key to the success of the conductivity meter within the food industry comes through the materials used during design and development. The conductivity of the device is dependent on temperature. If the temperature rises, the conductivity increases and likewise, if it drops then the conductivity reduces.

Within the device is a sensor tip that can be made out of both metal and a special plastic called PEEK. This is certified for food contact. Through extensive research, Baumer discovered that when combined with metal, PEEK could actually impair food safety. This is due to persistent cleaning causing stress to the metal/PEEk bond due to their very different thermal expansion rates. Ultimately, it means that metal and PEEK are incapable of enabling a tight, hygienic bonding, with stress and leakage being the likely conclusion.

How the CombiLyz conductivity sensor solved the problem of thermal stress due to temperature change

Following their research and through working closely with some of the leading companies within the food industry, Baumer came up with a solution: The CombiLyz Conductivity Sensor. Where the CombiLyz differs and excels in comparison to the previous conductivity sensors, is through the unique design of both the sensor tip and temperature elements.

Instead of mixing metal and PEEK as done previously, Baumer design both parts completely out of PEEK plastic. The result was a one-piece design that provides unique value to the market.

To complete the design of this device, Baumer calls upon its vast ultrasonic hygienic welding experience. The welding ensures that there were no gaps in the device, ultimately ruling out the possibility of leakage. This is a frequent occurrence due to cracking because of the thermal stress due to temperature change. Furthermore, the device was subject to helium leak tests to ensure this is no longer an issue.

EHEDG tests were also carried out on the CombiLyz conductivity sensor. These came back with excellent results in cleanability, further proving its valve for use in CIP and SIP processes. For more information about the CombiLyz conductivity sensor, or any of Baumer’s other products visit www.baumer.com.