Fibre optic sensing solutions

Louise Smyth

Stéphane Rohrbach discusses how to facilitate monitoring and maintenance in extreme environments

Choosing reliable, easy-to-maintain systems that simplify monitoring and reduce costly maintenance operations is a major challenge in hazardous offshore and onshore environments. To cover long distances between oil and gas extraction points and control centres, precise sensing capabilities and fast data transfer are key. Innovative fibre optic and miniature connectivity solutions help meet this challenge.

Fibre optics are ideal for gathering real-time information, eg, for monitoring drilling extraction for irregularities. Providing lightweight and sparkle-free interconnection is important in sensing, and being quick to deploy and easy to maintain also matters, because associated downtimes can lead to considerable loss of earnings when the sensing system is a critical part of the security loop associated with the main production.

Fibre optic sensing is challenging because the physical properties of light into the fibre are affected by strain, temperature or sound. Several technologies enable local measurement – using sensors at chosen points along the fibre (eg, fibre bragg grating (FBG) technology for measuring localised pressure, strain, temperature and flow) – or distributed sensing – with sensing occurring all along the fibre (e.g. Raleigh, Brillouin or Raman backscattering for continuously monitoring acoustics, temperature and strain in pipelines, oil drilling or local environments).

These technologies require top-of-the-range optical performances to work flawlessly (with a good signal-to-noise ratio). Insertion loss must be minimal, and return loss is critical, as the returning light contains information about the measurement. Optical connectors are generally specified in APC end faces for single mode, guaranteeing minimal return loss. Manufacturing a reliable APC termination requires premium polishing equipment and skilled operators. Each termination must be certified in terms of end-face geometry to guarantee good physical contact. Moreover, each APC terminus has to be keyed properly and the shell designed to meet strict termini design requirements.

Fischer Connectors designs high-performance, ultra-resistant fibre optic cable assembly solutions. For rapid field deployment, the Fischer FiberOptic Series offers a ready-to-use solution, whose ruggedness and push-pull locking system ensure quick, safe connections. Its removable sleeve holder makes it easy to clean. Pre-terminated cable assemblies are available in single mode APC and other fibre types, for perfect integration into sensing applications. The rugged, sealed bodies (IP68 mated, IP67 unmated) ensure reliable mechanical protection, without compromising on optical performance – thanks to their shell design and butt joint termini. Available in 1, 2 and 4 fibres, there are varied body styles to fulfil any integration need. 

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Stéphane Rohrbach is Engineering Director at Fischer Connectors

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