Chemical reactions in material testing picked up with thermal imaging
The Safe Oxygen Working Group at the Federal Institute for Materials Research and Testing (BAM), Berlin, Germany is using thermal imaging to test the reaction of different materials and component designs to oxygen.
Pressurised oxygen is widely used in chemical plants, iron ore smelting, hospitals, and for scuba diving. However the susceptibility of certain materials and component designs to large quantities of pressurised oxygen is highly unpredictable and can lead to strong reactions resulting in catastrophic failures.
Researchers at BAM are using a thermals camera from Flir to test materials according to the ‘oxygen pressure shock test’ methodology. Here, the test material is finely divided to small flakes or grains, put into a stainless-steel container and exposed to pressurised oxygen. Flir’s SC-Series thermal imaging camera is used to detect the temperature rise on the outer surface of the container.
The camera can detect any temperature rise associated with a chemical reaction of the material with oxygen. Performing these tests at different starting temperatures and at different oxygen pressures, potential reaction thresholds can now be determined accurately by the researchers.
Traditionally, BAM had used thermocouple sensors and spot pyrometers to measure temperature. However these methods had limitations: thermocouples can be easily destroyed if there is a strong reaction with oxygen and spot pyrometers measure only temperature at one location.
The Flir SC-Series thermal imaging camera used at BAM contains an indium antimonide (InSb) focal plane array (FPA) detector providing thermal images at a resolution of 320 x 240 pixels and a sensitivity of 13mK (0.013°C). This research grade camera is capable of capturing high contrast thermal images at a frame rate of 432Hz.
For BAM oxygen pressure shock testing requirements, the camera was calibrated to measure temperatures as high as 1,800°C accurately.