Articles

about Fiber Bragg Gratings (FBG), FBG Sensors and Monitoring Systems

How does distributed acoustic sensing work?

on July 1, 2019

1000px-Distributed_Acoustic_SensingDistributed fiber optic sensing is considered to be an advanced technology that allows changing the principle of infrastructure management. The fiber optic technology converts optical fibers into thousands of sensors and controls tens of kilometers of an asset with a single FBG interrogator. Thus, optical fiber sensors are a highly cost-effective fiber optic solution that is used by numerous industries every year.

Herewith, Distributed Acoustic Sensing or DAS technology has the wider scope of potential fiber optic applications, both scientific (seismic, mechanical) and industrial (security, integrity, operation monitoring) because DAS detects vibrations along the optical fiber. It should be noted that the detection and analysis of sound waves remains one of the most effective techniques for sensing information.

The principle of distributed acoustic sensing operation is based on the use of a fiber optic cord that is placed in an acoustic sensing housing that picks up sounds along the length of the cord. Therefore, DAS technology makes it possible to obtain a more detailed scan of hazardous or hard-to-reach places.

Moreover, the additional DAS benefit includes the possibility to identify the strain of the fiber optic cord to help prevent damages. The fields of DAS applications include the sensing disturbances around fracking operations underground that is possible to perform during and after the process to ensure safety. Also, distributed acoustic sensing can be applied to guide the fracking operation to the right underground deposits.

Generally, the DAS system is used to offer less disturbance to places applied for oil drilling and fracking. Nevertheless, DAS technology is ideally suited for the measurement of seismic events and control of fault lines with less of an equipment footprint and impact on the surrounding area.

Distributed acoustic sensing offers the following advantages that include:

  • High precision due to its linear response; 
  • Very high sensitivity; 
  • Great coverage, exceeding 70 km; 
  • The possibility of programming real-time applications directly on the device. 

Finally, the fields of DAS applications continue expanding. At the present time, it includes perimeter intrusion detection, third-party interference detection, power cable monitoring,  traffic monitoring (roads, railway, subway), seismic activity monitoring, subsea cable monitoring, asset integrity, oil, gas and water pipelines.

Optromix is a DAS system manufacturer that provides top of the line distributed acoustic sensing systems suitable for monitoring of commerce networks. If you have any questions or would like to buy a DAS system, please contact us at info@optromix.com

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editorHow does distributed acoustic sensing work?

Fiber optic inclinometer demonstrates the versatility of FBG sensors

on June 24, 2019

Inclinometer_on_Arduino_(1749427669)Fiber optic inclinometer is considered to be one of the most important optical fiber devices used in numerous fields of application. For example, in geophysical engineering, the inclinometer based on the fiber Bragg grating technology (FBG) allows monitoring the angle of inclination at regular intervals along the borehole to profile the land displacement.

Current fiber optic inclinometers utilizing FBG sensors demonstrate a high level of sensitivity and angle of measurement resolution of 0.006°. It should be noted that traditional inclinometers have disadvantages when it comes to their involuntary twist during the process of installation. And optical fiber sensors were widely thought to overcome these limitations due to the absence of moving parts.

Nevertheless, the combination of traditional inclinometers with FBG technology enables to resolve the challenge and make the fiber optic inclinometers’ operation independent of twisting, therefore, the precision remains constant. Moreover, despite numerous fiber optic techniques that measure temperature, strain, pressure and other parameters, new fiber optic inclinometer based on a fiber’s taper and a long-period fiber Bragg grating has been recently developed.

The principle of the fiber optic device is based on the use of conventional fiber Mach-Zehnder interferometer that allows dividing the incoming light between two optical fibers and recombining it at a second junction. To be precise, in a Mach-Zehnder system, a long-period fiber Bragg grating dissipates light at its resonant wavelength from the optical fiber core into the cladding, while a second-long period FBG takes light from the cladding back into the fiber core.

The novel fiber optic inclinometer is a simpler device that includes only a single long-period fiber Bragg grating. Moreover, it uses the taper that enables to increase the core field so that part of its light is coupled into the cladding. The fiber optic inclinometer offers the following advantages in its operation:

  • the  immunity  to electromagnetic  interference;
  • the  high sensitivity;  
  • the  compact size;  
  • the multiplexing and remote interrogation abilities.

This optical fiber device based on the interferometer was tested in the measurement of angular displacement. During the experiment, the optical fiber on either side of the taper was sheathed in capillary tubes and then twisted accurately at the taper. Thus, such a bend influences the fringe visibility, but not the location of the fringes.

Optromix is a FBG sensor manufacturer that provides top of the line FBG sensing systems suitable for monitoring of the constructions’ inclination. If you have any questions or would like to buy a FBG product, please contact us at info@optromix.com

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editorFiber optic inclinometer demonstrates the versatility of FBG sensors

The use of fiber optic sensing solutions on active warships

on June 17, 2019

us-army-379036_640The researchers from NASA Armstrong Flight Research Center form a partnership with members of the Naval Surface Warfare Center to create fleet maintenance capabilities with the help of new fiber optic sensing systems. Thus, the development of novel highly promising fiber optic sensing solutions becomes possible.

The thing is that fiber optic technology is considered to be one of the most essential and promising techniques, and the cooperation of the mentioned above organizations may help to find the solution to all current challenges. Herewith, there was a project of Remote Environmental and Condition Monitoring Systems that could be restarted again with the help of new possibilities of optical fiber technology offered by companies.

The main function of fiber optic sensing systems is the record of every parameter. For example, today fiber optic sensors are applied for monitoring of temperature, relative humidity, shock, and vibration. Future fiber optic applications include the monitoring of hypergolic propellant fuels, liquid detection, contamination, radiation, strain, and electric and magnetic fields.

Fiber optic sensing solutions allow fulfilling a need to control high valued assets applying fiber optic sensing technology that can be installed with live ordnance. Moreover, the fiber optic sensing system was tested on a self-defense test ship before its installation on real warships.

Such fiber optic technology enables to increase confidence in real-time fiber optic applications on active warships and ensure sensing systems are ready before future improvements. This optical fiber sensing system contains as many fiber optic sensors as possible to develop a new project that allows demonstrating and detecting main challenges in a relatively short time.

The Office of Naval Research offers fiber optic sensing solutions that are able to monitor, identify, and forecast the health of most critical components, hot spots, fatigue and damage-prone parts of weapon systems in a reliable and economical way.

Such fiber optic technology may enhance sensing systems while cutting the maintenance cost, current parts life and new materials. The advantages of fiber optic sensing solutions are based on the application of lightweight, compact fiber optic sensors compared to traditional big, heavy and hard resisting gages.

Finally, the researchers from NASA developed fiber Bragg Grating or FBG (a fiber optic sensor that reflects certain wavelength and sends all others), as well as two techniques they apply in their fiber optic sensing systems: conventional Wavelength Division Multiplexing and unique FBG Interrogation Technology called the Optical Frequency Domain Reflectometry.

If you want to obtain a highly efficient sensing system, you should choose Optromix company. Optromix is a manufacturer of innovative fiber optic products for the global market. The company provides the most technologically advanced fiber optic solutions for monitoring worldwide. Optromix is a fast-growing vendor of fiber Bragg grating (FBG) products line such as fiber Bragg grating sensors, FBG interrogators and multiplexers, distributed acoustic sensing (DAS) systems, distributed temperature sensing (DTS) systems. If you are interested in FBG sensors and want to learn more, please contact us at info@optromix.com

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editorThe use of fiber optic sensing solutions on active warships

FBG pressure sensors for pipeline leakage detection

on June 10, 2019

The technology of fiber Bragg grating or FBG is widely used in numerous sensing technology fields of application. For example, today FBG pressure sensors are installed to detect the leakage process of prestressed concrete cylinder pipe. This type of pressure sensor is based on the use of a Bourdon tube with two fiber Bragg gratings attached on its outside and inside surfaces.

winter-681175_640Such wider sensing application is caused by an increasingly large number of attractive characteristics of FBG sensors that include intrinsic safety, immunity to electromagnetic fields, remote sensing, and large multiplexing capabilities. Therefore, the pressure parameter remains the most important physical factor in the process industry.

Nevertheless, conventional pressure sensors based on electrical train gauge, vibration wire, mechanics have several disadvantages that include the absence of the ability to withstand harsh environmental conditions with critical electromagnetic interference, adventurous chemicals, or explosion matters. Moreover, such sensing systems do not allow making pressure’s multipoint measurement and online monitoring at a long distance.

It should be noted that the intrinsic pressure sensitivity of an FBG sensor is considered to be about 3.04 pm/MPa, which is quite a low index for the practical pressure measurement. Despite numerous ways proposed to increase the sensitivity factor of FBG pressure sensors, such as the installation of FBG in polymer, soldering metal-coated FBGs on a free elastic cylinder, and embedding the FBG fiber to a diaphragm, all these techniques propose relatively complex structures which are difficult to produce.

The thing is that the prestressed concrete cylinder pipe is widely used for water transportation in different areas, for example, municipal, industrial, and plant piping systems. Thus, the role of FBG pressure sensors for security monitoring and reliability management of huge cylinder pipes remains very important because now the sensing technology still faces numerous challenges.

Nevertheless, the use of a Bourdon tube in FBG pressure sensors as the spring element allows detecting spring element. Herewith, the measurement sensitivity increases and becomes 1.414 pm/kPa in a range from 0 to 1 MPa while the correlative coefficient is 99.949%. That is the reason why the development of a totally new pressure sensor is planned, which probably find new FBG sensing applications of pressure’s quasi-distributed measurement or online monitoring in industry and manufacture fields.

If you want to obtain a highly efficient sensing system, you should choose Optromix company. Optromix is a manufacturer of innovative fiber optic products for the global market. The company provides the most technologically advanced fiber optic solutions for monitoring worldwide. Optromix is a fast-growing vendor of fiber Bragg grating (FBG) products line such as fiber Bragg grating sensors, FBG interrogators and multiplexers, distributed acoustic sensing (DAS) systems, distributed temperature sensing (DTS) systems. If you are interested in FBG sensors and want to learn more, please contact us at info@optromix.com

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editorFBG pressure sensors for pipeline leakage detection

Distributed temperature sensing of fiber optics under harsh conditions

on June 3, 2019

water-1867234_640According to a recent study, the technology of distributed temperature sensing allows demonstrating the mechanical properties of fiber optics under harsh conditions. The fact is that numerous land and undersea oil procedures depend heavily on distributed temperature sensing for providing safety and functionality in severe environments.

Usually, the manufacturers use silica-based fiber optics for distributed temperature sensing and distributed acoustic sensing, where temperature and acoustic signals are transmitted and recorded continuously along the length of fiber sensor cable. Such fiber optic solution for FBG interrogator of 15 km length enables well and pipeline operators to apply fiber-based distributed sensing technology to measure the whole wellbore or pipeline span with a resolution of 1 m or less virtually in real time.

For example, the technology of distributed temperature sensing with fiber optics is used in the operation of steam-assisted gravity drainage or SAGD technique, which the main goal is the production of heavy crude oil and bitumen materials. Nevertheless, it is only one example, while distributed temperature sensing has numerous fiber optic applications.

It should be noted that the distributed temperature sensing system monitors the following extreme environments while optical fiber operation: high temperatures and pressures, ionizing radiation and aggressive chemicals in the environment. However, in order to be applied in such severe conditions, fiber optics have to be highly reliable, while transmitting optical power with a minimum of added signal loss.

Most of the fiber sensor cables used in fiber optic applications contain a silica-based core and cladding because of the silica benefits that include high optical fiber transmission, superior thermal stability, and mechanical reliability. Herewith, the use of a polymer coating in fiber cables provides the mechanical protection of fiber optics and minimization of bend-induced optical attenuation.

The technology of distributed temperature sensing also enables to detect the factors limiting the performance of fiber optic cables at elevated temperatures and/or in aggressive conditions. The most frequent failures for fiber optics are related to added attenuation or loss of mechanical strength. Herewith, failure criteria differ from each other and depend on the type of fiber optic application.

If you want to obtain a highly efficient distributed temperature sensing system, you should choose Optromix company. Optromix is a manufacturer of innovative fiber optic products for the global market. The company provides the most technologically advanced fiber optic solutions for monitoring worldwide. Optromix is a fast-growing vendor of fiber Bragg grating (FBG) products line such as fiber Bragg grating sensors, FBG interrogators and multiplexers, distributed acoustic sensing (DAS) systems, distributed temperature sensing (DTS) systems. If you are interested in DTS systems and want to learn more, please contact us at info@optromix.com

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editorDistributed temperature sensing of fiber optics under harsh conditions

NASA offers collaboration to companies providing fiber optic solutions

on May 27, 2019

NASA_logo.svgThe members of NASA company have decided to offer collaboration to companies providing fiber optic sensing solutions for monitoring of structures and asset management. The fact is fiber optic sensing technology unifies advanced optical fiber sensors and innovative algorithms that allow making precise and cost-efficient monitoring numerous crucial parameters in real time.

The mentioned abilities of fiber sensing solutions play a significant role in structural health monitoring and tank gauging applications. The following parameters are taken into consideration: position or deformation (2D and 3D displacement, twist and rotation), the level of stiffness (bending, torsion and vibration), operational loads (bending moments, shear loads, and torques), magnetic fields (different defects in safety-critical structures made from metal materials), and stress/strength parameters such as pressure or fatigue and breakage prediction.

Moreover, fiber optic sensing systems enable to provide not only the structural health monitoring of a tank but optical fiber technology is able to sense the inventory of the tank: for example, the level of the tank’s content, evaporation rate, temperature (that can varies from cryogenic up to 300 degrees Celsius), and stratification (oil vs. water, sediment vs. liquid, and thermal layers).

Fiber optic sensing solutions offer numerous advantages that include:

  • low cost opening new fields of application across industries;
  • low  power consumption of fiber sensors due to highly efficient  algorithms and high-speed processing platform enabling quick  data processing and real-time analysis;
  • fast speed and high level of efficiency;
  • precise and adaptive fiber optic technology because of the ability of optical fiber sensors to automatically increase resolution  where/when needed;
  • easy installation of fiber device;
  • high reliability of operation even in humid/liquid environments and harsh temperature conditions.

The numerous abilities of fiber optic sensing system create a potential solution for a myriad range of monitoring application. Structural health monitoring and integrity, tang gauging, active control, safety and protection area, non-destructive evaluation and medical usage refer to potential optical fiber applications.

The principle of fiber sensor operation is based on the use of fiber Bragg grating sensors that are installed in an optical fiber at intervals as small as 0.25 inches (0.64 cm). Finally, such fiber optic sensing system allows monitoring strain, stresses, structural instabilities, temperature distributions, and numerous other engineering parameters in real time with a single instrumentation system which weight is less than 10 pounds (4.54 kg). Herewith, the fiber optic solution is able to differentiate between liquid and gas states in a tank or other container, offering precise measurements.

das_1If you want to obtain a highly efficient sensing system, you should choose Optromix company. Optromix is a manufacturer of innovative fiber optic products for the global market. The company provides the most technologically advanced fiber optic solutions for monitoring worldwide. Optromix is a fast-growing vendor of fiber Bragg grating (FBG) products line such as fiber Bragg grating sensors, FBG interrogators and multiplexers, distributed acoustic sensing (DAS) systems, distributed temperature sensing (DTS) systems. If you are interested in FBG sensors and want to learn more, please contact us at info@optromix.com

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editorNASA offers collaboration to companies providing fiber optic solutions

Absolutely new optical gauge allows cutting well surveillance costs

on May 20, 2019

Oil_wellFiber optic technology is highly promising now, in spite of the fact that fiber optic solutions found their place in numerous fields of application, the optical fiber sphere still continues developing. Thus, recently a group of researchers from the UK demonstrated a novel optical pressure-temperature gauge of compact size.

The optical gauge is considered to enlarge the fiber optic application, especially when it comes to well surveillance area. Moreover, this optical device allows cutting all the costs and offering a new alternative to conventional downhole fiber sensors and other electronic logging tools.

Also, it should be mentioned that it is possible to combine the optical gauge with other devices, for example, with a simple deployment mechanism and distributed sensing technology, adding new properties and offering savings of 50-90% compared to traditional logging techniques.

A fiber optic gauge is a special tool that is based on a fiber Bragg gratings without using electronics, external connections or power supply equipment. Herewith, optical gauges provide the following advantages that include:

  • Immunity to electromagnetic fields;
  • Potential application in highly explosive environments;
  • Ability to withstand high vibration loads without any mechanical failure of sensor material;
  • Reduced number of connection lines and consequently, less impact on test purposes;
  • Low interconnection is required because of the possibility to include numerous sensors with different fiber Bragg grating wavelengths in one optical fiber.

The novel optical gauge can be installed in the fiber optic line and used in harsh atmospheres. Moreover, this fiber optic device is able to measure up to 10,000 psi (689 bar) and 150°C (302°F), optionally enlarged to 20,000 psi (1,379 bar) and 300°C (572°F).

Herein, the size of the optical gauge is about 10 cu mm, that is why the device can be easily implemented in various optical sensors and even installed in narrow access wells to log data during descent and to capture bottom hole temperature and pressure over time.

Finally, the optical pressure-temperature gauge is able to operate several months without human control, streaming real-time, live well information along the optical fiber back to surface. Usually, fiber optic sensors are applied in complex surveillance systems that have a high cost, sometimes they need either batteries or electrical power as well as special equipment compared to the novel optical gauges. Nevertheless, FBG sensors remain number one in the market today due to their light weight, simple installation and relatively low cost.

If you want to obtain a highly efficient sensing system, you should choose Optromix company. Optromix is a manufacturer of innovative fiber optic products for the global market. The company provides the most technologically advanced fiber optic solutions for monitoring worldwide. Optromix is a fast-growing vendor of fiber Bragg grating (FBG) products line such as fiber Bragg grating sensors, FBG interrogators and multiplexers, distributed acoustic sensing (DAS) systems, distributed temperature sensing (DTS) systems. If you are interested in FBG sensors and want to learn more, please contact us at info@optromix.com

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editorAbsolutely new optical gauge allows cutting well surveillance costs

FBG sensors: a comprehensive review

on April 29, 2019

Building Under White Clouds during Day TimeA fiber Bragg grating is an optical interferometer embedded in an optical fiber. At the same time, fiber optics combined with certain substances (usually germanium) can change its refractive factor when the fiber is exposed to ultraviolet light. If such a fiber is illuminated with ultraviolet light with a specific spatial periodic structure, the optical fiber becomes a kind of diffraction grating. In other words, this optical fiber will almost completely reflect the light of a certain, predetermined range of wavelengths, and transmit light of all other wavelengths.

The FGB application includes the following fields:

  • Point sensors (that is able to measure deformation, temperature, pressure, tilt, displacement), embedded in composite materials and others;
  • Laser systems and amplifiers (filters, mirrors);
  • Telecommunications (dispersion compensation modules, WDM technology);
  • Research and development.

For decades, electrical sensors (tensor-resistive, string, potentiometric, etc.) have been the main method of measuring physical and mechanical phenomena. Despite their widespread use, electrical sensors have several disadvantages, such as loss during signal transmission, sensibility to electromagnetic interference, the need to organize a spark-resistant electrical circuit (if there is a danger of explosion). These mentioned above limitations make electrical sensors unsuitable or difficult to use for a number of applications.

The use of fiber optic sensors is an excellent solution to these problems. In fiber optic sensors, the signal is light in the optical fiber instead of electricity in the copper wire at traditional electrical sensors.

Over the past twenty years, a huge number of innovations in optoelectronics and in the field of fiber optic telecommunications has led to a significant reduction in prices for optical components and to a significant improvement in their quality. This factor allows fiber optic sensors to move from the category of experimental laboratory tools to the category of widely used devices in various areas.

A fiber Bragg grating or FBG acts as a sensitive element of point fiber optic sensors, which is capable to reflect certain wavelengths of light and transmit all others.  This effect is achieved by periodically changing the refractive index in the core of the fiber optics.

When the laser light passes through an optical fiber, a part of it is reflected from the fiber grating at a certain wavelength. This peak of reflected light is registered by measuring equipment. As a result of the numerous parameters influence, the interval between the FBG bundles and the refractive index of the fiber optics change.

Consequently, the wavelength of the light reflected from the fiber Bragg grating changes. In addition, it is possible to determine the exact characteristics of the changes by changing the wavelength. In fiber optic sensors based on Bragg gratings, the measured value is converted to a Bragg wavelength offset. The recording system converts the wavelength offset into an electrical signal.

The sensing element of such FBG sensor does not contain electronic components and therefore it is completely passive, which means it can be used in the area of increased explosiveness, aggressiveness, strong electromagnetic interference. Numerous fiber Bragg gratings can be installed on a single fiber, each of which gives a response at its own wavelength. In this case, instead of a point sensor, we get a distributed sensing system with multiplexing along the wavelength.

The use of the light wavelength as an information parameter makes the FBG sensor insensitive to the long-term changes of the parameters of the source and radiation detector, as well as random attenuation of power in the optical fiber.

The following types of fiber optic sensors  based on FBG technology are used for automated monitoring:

The principle of FGB sensor operation is based on the modulation of one or several properties of a propagating light wave (intensity, phase, polarization, frequency), which change occurs with a change in the measured physical quantity.

The basis of fiber-optic sensing technology is optical fiber – a thin glass thread that transmits light through its core. The optical fiber consists of three main components: core, shell, and coating. The shell reflects the scattered light back into the core, allowing light to pass through the core with minimal loss.

It can be achieved by a higher refractive index in the core relative to the shell, resulting in a complete internal reflection of light. The outer coating protects the fiber optics from external influences and physical damage. It can consist of several layers depending on the required protection.

The advantages of FBG sensors include:

  • Wide sensing range;
  • Possibility to integrate the FBG sensing system into the object structure;
  • Full fire and explosion safety;
  • Long distance signal transmission;
  • Integration of several fiber optic sensors in one channel;
  • Insensitiveness to electromagnetic and radio frequency influences;
  • No need for recalibration (stable over time under constant external conditions).

Bridge, Australia, BridgeAt the moment, most of the sensors used in the world are electrical sensors. As it was mentioned above, in optical sensors based on fiber Bragg gratings, the signal is light passing through an optical fiber (instead of an electric current passing through a copper wire). This fundamental difference allows FBG sensors to overcome many problems typical for electrical sensors.

Optical fibers and sensors are non-conductive, electrically passive and immune to electromagnetic interference. Monitoring with a tunable high-power laser system allows sensing over long distances with virtually no signal loss. In addition, each optical channel is able to monitor a variety of FBG sensors unlike the electrical channel, which significantly reduces the size and complexity of such a sensing system.

Optical sensing systems are ideal for use in conditions where conventional electrical sensors (strain gauge, string, thermistor, etc.) can be difficult to use (long distances, EM fields, explosion safety, etc.).  It is easy to switch to fiber optic solutions since the installation and operation of optical sensors are similar to traditional electrical sensors.

Understanding the principles of FBG operation and the benefits of Bragg grating sensor application can greatly facilitate the solution of various problems in the field of sensing measurement (for example, monitoring of structures).

Nowadays FBG sensors are applied in various fields that require precise and fast measurements. Fiber Bragg sensing systems can be used in aeronautic, automotive, civil engineering structure monitoring, undersea oil exploration, in the mining industry, geotechnical engineering, structural engineering, tunnel construction engineering, etc.

The most promising application of FBG sensors is medicine. Now FBG technology is highly used for fiber-based biomedical sensing including biosensing, safety or security, and structural health monitoring. FBG sensors offer a new and effective way of real-time measurements. They can be applied in laser systems, medical tiny intra-aortic probes and body sensors for biochemical analysis making.

For example, today fiber Bragg gratings apply optical-fiber sensing probes that are able to dissolve due to such ability as controlled solubility in a physiological environment. Thus,  FBG technology enables safer diagnostic of sensitive human organs and there is no need for a surgical extraction. The development of FBG continues, and it is possible that very soon new FBG sensors with improved characteristics appear.

If you want to obtain a highly efficient sensing system, you should choose Optromix company. Optromix is a manufacturer of innovative fiber optic products for the global market. The company provides the most technologically advanced fiber optic solutions for monitoring worldwide. Optromix is a fast-growing vendor of fiber Bragg grating (FBG) products line such as fiber Bragg grating sensors, FBG interrogators and multiplexers, distributed acoustic sensing (DAS) systems, distributed temperature sensing (DTS) systems. If you are interested in FBG sensors and want to learn more, please contact us at info@optromix.com

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editorFBG sensors: a comprehensive review

Fiber optic solutions for fire detection and temperature measurement

on April 22, 2019

Fire, Coals (1)Proper fire detection in the mining area is the number one priority because fire can evoke damages to valuable assets, downtime in operation and even loss of lives. Herewith, the installation of fire protection devices can be complicated by harsh environmental conditions of the mining area because industrial equipment produces dirt, dust, humidity and corrosive atmospheres in the production, storage or transport of goods. Nevertheless, the application of modern fiber optic sensors based on distributed temperature sensing or DTS is considered to be a proven and efficient technology for fire detection and temperature measurement.

The fact is DTS technology provides precise temperature measurement along the length of a conveyor belt due to the use of autonomous fiber optic cables, therefore, even very long conveyor routes can be efficiently monitored. Thus, cases of fires and overheating during mining operation can be quickly and easily identified and localized to within one-meter precision by distributed temperature sensors, enabling to activate the safety countermeasures. Also, it should be mentioned that it is required proper installation of the fiber optic sensor cables and adjustment of the alarm zones for heat detection of industrial rollers.

Nowadays mining industry applies fiber optic linear heat detection systems for these purposes, however, the new distributed sensing technology may significantly improve and increase the protection of assets in combination with the one mentioned above. The principle of DTS technology operation is based on the use of optical fibers as a distributed microphone, moreover, it means that fiber optic sensors allow measuring not only the temperature but also the acoustics. Such additional information is important because it helps to determine potential sources of danger and improves the whole purpose of fire prevention. To be precise, the DTS is highly important in hot roller detection that is the main reason for conveyor fires.

Also, it is difficult to identify the initial smoldering stage with traditional techniques, herewith, the majority of common gas detecting systems do not work properly because of high air currents. An optical fiber based on distributed temperature sensing technology, in its turn, provides numerous benefits during both normal operation and dangerous situation that include:

  • Reliable fiber optic cable that is resistant to dirt and dust;
  • Long distance (up to 10 km) and up to 4 measurement channels monitor several conveyors with one DTS system;
  • Practically maintenance-free;
  • Accurate localization of fires and hot rollers;
  • DTS is able to detect fires in spite of unfavorable environmental conditions.

Optromix is a DTS system manufacturer that provides top of the line distributed temperature sensing systems suitable for monitoring of commerce networks. If you have any questions or would like to buy a DTS system, please contact us at info@optromix.com

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editorFiber optic solutions for fire detection and temperature measurement

Fiber Bragg grating sensors provide groundwater flow sensing

on April 15, 2019

Groundwater flow sensing is highly important when it comes to the extraction of drinking water because it allows for avoiding well clogging and pollution. Nevertheless, fiber Bragg grating sensors with optical fibers are considered to be a promising new technique for monitoring of groundwater flow.

Water, Flow, (1)

The fact is that FBG sensors enable to identify even tiny changes in temperature, pressure, and fiber shape taking into account the sensitivities influenced by the packaging. Thus, fiber Bragg grating sensors are able to create a multiplexed sensor for the groundwater flow direction and magnitude.

It should be mentioned that the fiber-optic technology of FBG sensors has numerous application range, for example, in aerospace (load monitoring and shape sensing), in civil engineering (structural health monitoring), and in the oil and gas industry (temperature and pressure monitoring).

Today the technology of fiber Bragg grating sensing is also used for groundwater flow monitoring. FBG sensors allow measuring various physical properties, strain or temperature variations such as pressure, vibrations, and curvature of the optical fiber, herewith, fiber sensors make instant and precise measurements.

One more technique that can be used for monitoring is distributed temperature sensing, and the intended application influences directly the choice of technology – fiber Bragg grating or DTS sensing. DTS uses conventional single-mode or multimode fibers that find various application in the telecom industry, that is why DTS fibers are available in large lengths.

Moreover, the FBG sensors are possible to be written in traditional and specialty fiber optics, and consequently, their price increases per sensor number. However, the cost of fiber interrogators that are required for the DTS sensing data collection is five times more expensive than FBG units.

Traditional fiber Bragg grating sensors already possess a sufficient temperature resolution for the measurement of groundwater temperature changes without additional packaging. In addition, this FBG system has been recently tested to demonstrate its benefits for groundwater flow monitoring.

Thus, the experiment has shown that the use of FBG sensors enables to measure the relative temperature with a precision of 0.85 ℃ for the differential measurements. Also, the used fiber Bragg grating system is able to make a multiple-sensor interrogation with the possibility of an expansion into a larger distributed sensing network.

Finally, the data results presented that fiber Bragg grating sensors can be employed as a temperature sensing system in the subsurface environment, but in this case, they did not demonstrate any benefits over the existing fiber sensing technologies. Nevertheless, multiplexed fiber Bragg grating pressure or strain sensors would possibly find their application in groundwater flow monitoring.

Optromix is a fast-growing vendor of fiber Bragg grating (FBG) products line such as fiber Bragg grating sensors, FBG interrogators and multiplexers, Distributed Acoustic Sensing (DAS) systems, Distributed Temperature Sensing (DTS)systems. The company creates and supplies a broad variety of fiber optic solutions for monitoring worldwide. If you are interested in FBG sensors and want to learn more, please contact us at info@optromix.com

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editorFiber Bragg grating sensors provide groundwater flow sensing