Assessment of fiber optic sensors for aging monitoring of industrial liquid coolants (Conference Paper)
Riziotis, C.a, El Sachat, A.a, Markos, C.a, Velanas, P.a, Meristoudi, A.a, Papadopoulos, A.b
aNational Hellenic Research Foundation, Theoretical and Physical Chemistry Institute, 48 Vassileos Constantinou Avenue, Athens, Greece
bKleemann S.A., Kleemann Group of Companies, Kilkis Industrial Area, Kilkis, Greece
Proceedings of SPIE - The International Society for Optical Engineering, Volume 9359, 2015, Article number 93591YOptical Components and Materials XII; San Francisco; United States; 9 February 2015 through 11 February 2015; Code 112242
Lately the demand for in situ and real time monitoring of industrial assets and processes has been dramatically increased. Although numerous sensing techniques have been proposed, only a small fraction can operate efficiently under harsh industrial environments. In this work the operational properties of a proposed photonic based chemical sensing scheme, capable to monitor the ageing process and the quality characteristics of coolants and lubricants in industrial heavy machinery for metal finishing processes is presented. The full spectroscopic characterization of different coolant liquids revealed that the ageing process is connected closely to the acidity/ pH value of coolants, despite the fact that the ageing process is quite complicated, affected by a number of environmental parameters such as the temperature, humidity and development of hazardous biological content as for example fungi. Efficient and low cost optical fiber sensors based on pH sensitive thin overlayers, are proposed and employed for the ageing monitoring. Active sol-gel based materials produced with various pH indicators like cresol red, bromophenol blue and chorophenol red in tetraethylorthosilicate (TEOS), were used for the production of those thin film sensitive layers deposited on polymer's and silica's large core and highly multimoded optical fibers. The optical characteristics, sensing performance and environmental robustness of those optical sensors are presented, extracting useful conclusions towards their use in industrial applications.