Fiber-Optic Liquid Level Sensing by Temperature Profiling with an FBG Array

Abstract

We describe a fiber-optic system to measure the liquid level inside a container. The technique is based on the extraction of the temperature profile of the fiber by using a fiber Bragg grating (FBG) array. When the temperatures of the liquid and the gas are different, the liquid level can be estimated. We present a physical model of the system and the experimental results and we compare different algorithms to extract the liquid level from the temperature profile. We also show how air convection influences the temperature profile and the level of estimation accuracy. We finally show dynamic response measurements which are used to obtain the response time of the sensor. Turbomachinery monitoring is proposed as one possible application of the device.

Spectroscopic Techniques and Hydrogen-Sensitive Compounds: A New Horizon in Hydrogen Detection

“…These arrays based on Bragg gratings have been used to test liquid levels. Barone describes a method for level measurement based on temperature variations (gases and liquids have different temperatures) and using Bragg grating arrays [59]. This type of array may be used for hydrogen Figure 19.…”