FAQ about the OSMOS system

Below are some of the most frequently asked questions about the OSMOS system:

OSMOS system in general

Who is OSMOS?
What are the services which OSMOS supplies?
What does OSMOS stand for?
What are OSMOS’s references?
What are the main advantages of the OSMOS system?
Do the OSMOS system and its sensors have certification?
Is there any other company which produces OSMOS sensors?
What other kinds of optical fibre sensors are there on the market? How do they differ from those of OSMOS?
What is the difference between traditional sensors and optical fibre sensors?
What is the difference in price between an OSMOS monitoring system and a traditional monitoring system?
Which traditional sensors could be replaced by OSMOS sensors?

OSMOS sensors and their utilisation

Which are the main OSMOS sensors?
What can I measure with OSMOS sensors?
Can I use the OSMOS system for dynamic measurements?
What are the longest measurement lengths in which OSMOS Optical Strands are available?
Which is the maximum deformation which OSMOS optical sensors can measure?
What is the maximum distance between OSMOS sensors and the monitoring station?
On which kind of surface is it possible to install OSMOS sensors? How?
Can OSMOS sensors be used outside long-term?
Can I install OSMOS sensors in concrete?
How long is the useful life of sensors installed in concrete?
Can OSMOS sensors be reused?
Can OSMOS sensors be repaired?
How long is the expected useful life of OSMOS sensors?
How do variations in temperature affect OSMOS sensors?
Are OSMOS sensors resistant to natural and industrial corrosion?
Can I use OSMOS sensors at high temperatures?

The Monitoring station

How many OSMOS sensors and traditional sensors can I connect to a simple monitoring station?
Can I control a monitoring station by remote control?
How long can I take measurements using a battery?
Does the monitoring station have reliable alarm systems?
Can I see how stress develops in real time?
How are the measurements stored?
Can I make use of the data myself?
Can I export the data to other software programmes?

Applications

Can OSMOS sensors be used for monitoring bridges?
How can the deflection point mid-span be measured on a bridge?
Can OSMOS sensors be used with Weight in Motion Systems (WIMS)?
Is it possible to measure the tension of pre-stress cables?
Can OSMOS sensors be used for testing pile stakes?
Can OSMOS sensors be used in load trials?
Are OSMOS sensors suitable for monitoring around railway tracks?
Are OSMOS sensors suitable for monitoring historic buildings?
Are OSMOS sensors suitable for monitoring traditional buildings?
Are OSMOS sensors suitable for monitoring in major building projects?
What training to I need in order to be able to use the OSMOS system?

The OSMOS system in general



Who is OSMOS?
Founded 20 years ago, OSMOS specializes in surveillance engineering for the purposes of structural monitoring.
OSMOS is the global leader in this field because:
  • It has developed a concept of surveillance using sensors which supply clients with the information they need.
  • Since it was a pioneer in the area of structural monitoring, its technology has the advantage of being based on long experience.
  • It has by far the most well furnished portfolio of any other company in the business.


    • What are the services which OSMOS supplies?
    OSMOS offers the whole range of surveillance engineering services, if necessary, in partnership with other recognised and well-known players.


    What does OSMOS stand for?
    OSMOS stands for "Optical Strand Monitoring System", that is, a system which monitors using optical strands.


    What are OSMOS’s references?
    The following:
  • OSMOS has installed numerous systems throughout the world: over 500 in 17 countries (USA, Canada, Germany, Austria, Switzerland, Belgium, Holland, France, the UK, Denmark, Spain, Monaco, Russia, Japan, China, South Korea and Australia)
  • OMOS has installed its systems on the most diversified structures: including bridges, geotechnical structures, historic buildings, railway-related structures, hydraulic structures, industrial structures, real estate and public buildings.
  • Owing to the fact that they are robust and long-lasting, the oldest systems are still in situ: in France, the Eiffel Tower (13 years old), Stade de France football stadium (10 years), and many others installed over 8 years ago.
  • The most prestigious include the following: in France: the Eiffel Tower, Napoleon’s tomb (in the Invalides museum), the Louvre and in many cathedrals; France-UK: the Eurotunnel; in the US: the Ground Zero Area in New York.


    • What are the main advantages of the OSMOS system?
    The OSMOS system is the only one of its kind in which parameters are tracked in relation to the order in which problems affect the structure: firstly, defects which are early warning signs and thus critical, since they affect the stability of the structure; secondly, those which are marginally less important and arise as a result of the first.

    Consequently, the OSMOS system has been designed to use different types of sensors:
  • Firstly, sensors which pick up primary defects: OSMOS sensors;
  • Secondly, sensors which find the effects of the primary defects, such as inclinometers (tilt sensor) and accelerometers;
  • Lastly, sensors which identify causes: temperature sensors, anemometers, piezometers (small diameter water wells).
    • OSMOS sensors are able to measure deformations over long distances (but not only), within a precision in the order of one micron. These measurements are reliable over years. They are particularly suited to the long-term static and dynamic surveillance of civil engineering structures. OSMOS sensors are operational immediately, and in the most difficult environments. Users can manage them after only a short course, since special qualifications in optics are not required.



    Do the OSMOS system and its sensors have certification?
    Independent laboratories in France, Germany, Belgium and Japan have tested the performances of OSMOS systems. OSMOS produces all its systems under the strictest conditions in terms of quality control.





    Is there another company which produces OSMOS sensors?
    No, OSMOS is the only producer in the world of the OSMOS monitoring system.

    The production plants for manufacturing OSMOS sensors are solely in France.



    What other kinds of optical fibre sensors are there on the market? How do they differ from those of OSMOS?
    The main types of optical fibre sensors for structural surveillance available on the market are: the Fiber Bragg Grating (FBG) sensors, the Extrinsic Fabry-Perot Interferon (EFPI) meters and the Brillouin sensors.

    They use principles other than changes in light intensity, which is the principle chosen by OSMOS because it has many advantages.



    Optical fibre sensors which attempt to use alternative parameters are not really suitable for being embedded in building structures for the purposes of precision surveillance over the long-term.

    Most of them are used in telecommunications and have a number of defects such as not being very robust or reliable in the medium-term. Nor are they very satisfactory in terms of value for money.

    OSMOS sensors are far more efficient than other sensors in terms of the dynamic collection and recording of data.



    What is the difference between traditional sensors and optical fibre sensors?
    Optical fibre sensors take measurements by using the variations in the light beam caused by the object which is being measured. This means that they are insensitive to exterior influences such as electromagnetic fields (e.g. lightening, high voltage wires), corrosion, fluctuations in temperature and ageing.



    Which is the difference in price between an OSMOS monitoring system and a traditional monitoring system?
    The price of OSMOS sensors and the monitoring station is similar to that of traditional, equivalent sensors. Moreover, taking into consideration the fact that the system is easy to install and has a long useful life, the OSMOS system competes very favourably with traditional systems, as well as giving better results.



    Which traditional systems could be replaced by OSMOS sensors?
    OSMOS sensors have been especially designed to give the most vital information about structural stability, i.e. where stress is concentrated, which can be detected by variations in the level of the stress as well as by displacement.

    In consequence, OSMOS sensors replace sensors which function on the basis of stress or displacement, such as LVDT inductive sensors, wire vibration measurements, resistive stress gauges, and extensometers with rods or threads. Depending on the application, they may be used to replace inclinometers, whether they are geodesic or topographic.

    OSMOS sensors and their utilisation


    Which are the main OSMOS sensors?
  • Optical Strands: Measure variations in lengths over long measurement ranges





  • Optical extensometer: Measures local displacements






  • X-Trigger: Detects the threshold between two points





  • Caterpillar optic sensor: Measures geotechnical movements





  • Monitoring station: A signal processing unit for collecting and relaying data











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    What can I measure with OSMOS sensors?
    OSMOS sensors have been designed to process vital information, such as variations in stress, deformation and elongation, and transmit it in terms of static and dynamic measurements.


    Can I use the OSMOS system for dynamic measurements?
    The OSMOS system is capable of registering static and dynamic measurements (scanned at a maximum of 100 Hz) instantaneously, within the same time base.


    What are the longest measurement lengths in which OSMOS Optical Strands are available?
    Optical Strands come in standard lengths: 2 m, 5 m and 10 m. If requested, specific lengths up to 20 m can be produced.


    What is the maximum deformation which OSMOS optical sensors can measure?
    OSMOS Optical Strands have a maximum measuring range of 500 mm. In terms of dynamic tracking, they are precise within a range of +/- 0.002 mm.
    OSMOS optical extensometers have a measuring range of 5 mm. In terms of dynamic tracking, they are precise within a range of +/- 0.002 mm.
    Our EX-Large sensor has a measuring range of 500 mm. It is precise within a range of 0.5mm.


    Which is the maximum distance between the OSMOS sensors and the monitoring station?
    It may be up to 4 km without the use of amplifiers or signal conditioning units.


    On which kind of surface is it possible to install OSMOS sensors? How?
    OSMOS sensors can be installed on or in all kinds of building materials: such as concrete, metal, wood, masonry, mortar and rocks.

    Concrete    Metal      Wood     Masonry
    Mortar-Plaster    Rocks             


    The anchor points at the ends of the sensors can be attached to the building structure by being screwed in to it, bolted in, stuck on, or by any other mechanical attachment method.



    Can OSMOS sensors be used outside long-term?
    Yes. The OSMOS system is extremely robust and reliable in the long-term.

    For long-term use, it is easy to protect OSMOS sensors against natural elements, such as ultra violet rays, birds and rodents, as well as against mechanical attacks of all kinds, through simple and traditional methods, such as surrounding them by casings.


    Can I install OSMOS sensors in concrete?
    Optical Strands in flexible steel hoses are designed so that they can be cast in concrete, mortar or any other type of matter which can be shaped.





    How long is the useful life of sensors installed in concrete?
    Experience has shown that Optical Strands which are correctly installed in concrete stand up well to the casting process.


    Can OSMOS sensors be reused?
    Sensors installed on the surface of building structures can be used many times again. Sensors cast in concrete cannot be reused.


    Can OSMOS sensors be repaired?
    If the damage to the optical sensor was on the connection cable, it can be repaired merely by optical soldering on site. But, if the damage is to a sensitive part of the sensor, it would be advisable to replace it.


    How long is the expected useful life of OSMOS sensors?
    On the basis of experiments which accelerate ageing, the results of which were extrapolated to our actual experience, we believe that OSMOS sensors have a very long useful life. We consider that 90% of the sensors which work after they have been installed will last for at least 20 years, without necessitating heavy maintenance.


    How do variations in temperature affect OSMOS sensors?
    Very little (in comparison with the effects on the sensor’s support unit). Thus, an Optical Strand would be affected to the extent of 0.6*10-6 m/K, which is 20 times less than for steel.


    Are OSMOS sensors resistant to natural and industrial corrosion?
    OSMOS sensors are manufactured in extremely lasting materials (e.g. 316ti grade stainless steel, quartz). Thus, they can be used in most areas which may be subject to corrosion.
    If, however, they were to be used in environments where there are high levels of corrosion (e.g. the chemicals industry), we would examine each case individually.


    Can I use OSMOS sensors at high temperatures?
    Yes, OSMOS sensors have a working temperature range comprised between:
    -20°C and +60°C.

    The Monitoring station


    How many OSMOS sensors and traditional sensors can I connect to a simple monitoring station?
    It is possible to connect 4 OSMOS optical sensors, 6 traditional analog sensors and 2 temperature sensors to each data collection unit.
    It is possible to connect 5 data collection units to each signal processing unit, i.e. 20 OSMOS optical sensors, 30 traditional analog sensors and 10 temperature sensors.



    All traditional sensors can be connected to the monitoring station.


    Can I control a monitoring station by remote control?
    Yes, by means of a telephone modem used in conjunction with a wire connection or with GSM mobile telephony, it is possible to programme and control the monitoring station by remote control.


    How long can I take measurements using a battery?
    For when there is a power cut, we offer standard batteries which function autonomously for a period of 2 hours, or more, as required.
    For example it is possible to make the system totally autonomous for longer than a month, by connecting it to an independent electric power generator which supplies the system with electricity. Thus, it is autonomous from one visit to the site and another.



    It is also possible to supply the monitoring station with electricity by means of solar panels.





    Does the monitoring station have reliable alarm systems?
    If pre-programmed thresholds are exceeded, alarms are sent by e-mail, fax, and text messages or by means of SNMP (simple network management protocol) Trap messages.

    The alarm systems which are on site (e.g. sirens, safety barriers, red lights) can also be connected to the monitoring station.



    Can I see how stress develops in real time?
    Yes, the software programme offers two screens (the “dashboard” and the oscilloscope) which show data instantaneously.





    How are the measurements stored?
    All the information is stored in a data base in ASCII mode, or recorded directly onto an Excel sheet, if requested.


    Can I make use of the data myself?
    At OSMOS, we have developed our own data processing software, which is very user-friendly and functions according to requisite ergonomic criteria. Data can be recorded in the form of curves, graphs, bar charts or tables.



    This software has the following specific features:
  • Fourier transform, in order to determine the specific frequency components;
  • Formulae are established to find connections between the curves registered by all the sensors, and, if necessary, correct them.


    • Can I export the data to other software programmes?
    Data can be easily exported to Excel files, Mathlab programmes, as well as to other software programmes.

    Applications


    Can OSMOS sensors be used for monitoring bridges?
    OSMOS sensors have been designed for monitoring bridges. Depending on the type of information required, they allow for the collection of the parameters for immediate use: the level of safety at all times, extension of the useful life of the bridge, optimisation of the maintenance.
    Such parameters may consist of the maximum deflection at mid-span, shear stressstrain, compression stress in support pillars, rotation at the extremities of supporting beams, monitoring traffic, determining its natural frequency, static/dynamic measurements rations.





    How can the deflection point mid-span be measured on a bridge?
    By installing Optical Strands parallel to the neutral axis, above and below, it is possible to measure the average variations in the curve in the relevant section of the bridge by converting data so that it can be gauged during the course of tests. By installing 3 to 5 pairs of Optical Strands per bridge span, it is possible to obtain a valid curve function for the bridge as a whole.

    By integrating this function twice, we are able to calculate the horizontal and/or vertical deformations of the bridge. All this data is automatically processed by our software.



    NB:
    Bridges entail all kinds of construction materials, geometrical shapes and contexts. Since the OSMOS system can be used for the whole range of engineering structures, it can also be used for all kinds of structures.



    Can OSMOS sensors be used with Weight in Motion Systems (WIMS)?
    The OSMOS group has perfected a process which makes it possible to enter and classify in real time all relevant information on a particular section of road per traffic load, with advantages such as: the traffic is neither asked to slow down or to stop, speed is measured, the offending vehicles are identified, the system is reliable and robust in the long-term, the price is attractive.





    Is it possible to measure the tension of pre-stress cables?
    OSMOS sensors can be placed directly in the pre-stressing hose, when it is being installed, or on the matter which encases it.

    Can OSMOS sensors be used for testing pile stakes?
    Yes, they can be used during load trials carried out to obtain the final load capacity, the pile stake peak load, the lateral distribution of friction and, on the basis of how deep the pile stake is embedded, its lateral displacement.





    Can OSMOS sensors be used in load trials?
    Yes, the OSMOS group supplies the most reliable and most precise method of guaranteeing that the real bearing capacity of a support area corresponds to that required by the regulations.





    Are OSMOS sensors suitable for monitoring around railway tracks?
    Yes, the OSMOS system is particularly highly recommended for the premature detection of the subsidence which may occur underneath railway tracks.





    Are OSMOS sensors suitable for monitoring historic buildings?
    The system is totally suitable, owing to the following properties:
  • Embedded with the aim of being used for years, it is long-lasting.
  • It is safe: no electric current is involved, therefore there is no risk of sparks.
  • It is discreet: the general public is highly unlikely to see the sensors.
  • The fact that there is a long-measurement range makes it possible to bridge over local conditions, situations and circumstances and to ensure that measurements are reliable, even on varying construction materials (e.g. masonry).



    • Are OSMOS sensors suitable for monitoring traditional buildings?
    Yes, owing to its very wide range of products and prices, the OSMOS system can be used to monitor all types of buildings from skyscrapers to small houses.





    Are OSMOS sensors suitable for monitoring in major building projects?
    OSMOS has developed and perfected an automated monitoring system for clients who are in charge of overseeing large building works on a regular basis.


    What training do I need to be able to use the OSMOS system?
    In order to use the OSMOS system efficiently, it is necessary just to read the different manuals. We suggest, however, that in order to ensure that our system is not damaged during installation and that, once installed, it offers a high performance, you consider contracting OSMOS or one of our associate companies for the initial installation and connection on site.


    This list of FAQ and their answers is a live document which is constantly updated. Please do not hesitate to consult it regularly!
    Concept • The OSMOS group