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Proceedings Paper

Fully distributed optical fiber sensor for water and humidity monitoring
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Paper Abstract

Internal corrosion can occur when aqueous electrolytes are present inside natural gas transmission pipelines. Despite upstream gas dehydration treatments, liquid water can form through condensation of water vapor or may be introduced from plant upsets. With dissolved salts and acidic gases such as CO2 and H2S, aqueous electrolytes become very corrosive with increased conductivity and lower pH. Since water provides the electrolytes that initiate and sustain corrosion, detection of water can locate the spots for potential internal corrosion inside the pipelines. In this work, a simple optical fiber-based sensor for fully distributed water monitoring has been demonstrated and studied. The system consists of an unmodified off-the-shelf single mode (SM) optical fiber and an optical backscatter reflectometer (OBR) capable of measuring the spatial profile of strain changes along the fiber. The polymer jacket coating of the SM fiber is hydroscopic and serves as the water sensing layer due to expansion/swelling from water absorption. The swelling induced strain change is interrogated with the OBR to enable fully distributed water monitoring. This strain-based H2O sensor is sensitive to H2O molecules regardless of the phase (liquid or vapor) or the surrounding media. Strain changes were measured at different relative humidity levels from 0% to 100% to demonstrate reversibility and linear correlation between humidity and strain. This sensor has the advantages of fully distributed sensing, low cost, simple preparation, easy operation, and good sensitivity.

Paper Details

Date Published: 14 May 2019
PDF: 10 pages
Proc. SPIE 11000, Fiber Optic Sensors and Applications XVI, 1100007 (14 May 2019); doi: 10.1117/12.2519239
Show Author Affiliations
Ruishu F. Wright, National Energy Technology Lab. (United States)
Leidos (United States)
Mudabbir Badar, National Energy Technology Lab. (United States)
James C. Egbu, National Energy Technology Lab. (United States)
Ping Lu, National Energy Technology Lab. (United States)
Leidos (United States)
Michael Buric, National Energy Technology Lab. (United States)
Paul R. Ohodnicki Jr., National Energy Technology Lab. (United States)
Carnegie Mellon Univ. (United States)

Published in SPIE Proceedings Vol. 11000:
Fiber Optic Sensors and Applications XVI
Robert A. Lieberman; Glen A. Sanders; Ingrid U. Scheel, Editor(s)

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