Point temperature, strain, pressure sensors

  Although standard electronic sensors are sensitive to EMI (ambient noises in a measured signal) they are usually used in extreme environment, but cannot function without special high voltage protection and then most of the electronic materials are typically limited to temperature range:  up to +200°C and radiation range: up to kGy (1 Gy = 100 rad).

  Fiber optic sensors based on optical measurement principles are most viable solution to fully meet operational requirements in extreme environmental conditions. Fiber optic sensors and sensor networks consisting of fused silica glass feature good sensitivity with high mechanical and radiation resistance.

   The sensitive element is built into design of fiber optic cable to measure a certain parameter, while the remaining part of the cable is used for communication of optical signal to a processing unit. Depending on the design sensors provide measurements of strain, pressure, temperature evolution and can be categorized into various types, such as: Fabry-Perot, Mach-Zehnder, etc. or fiber optic Bragg grating (FPG).

Features and benefits of fiber-optic sensors:

• High resistance to EMI
• High sensitivity
• Robustness
• Consistent repeatability
• Wide dynamic range
• Spectral and spatial multiplexing of sensitive elements built in one or several lightwaves.
• Can be placed remotely from the sensing area
• Quick response to  changes in the measurand
• High resistance to corrosion and radiation  

Applications*:

1. Point accelerometers – seismometers.

  Highly sensitive compact buried seismometer connected to remote registration unit by means of low-observable electrical passive fiber optic cable 10 km length to detect intruder-induced ground motion. The calibrated data is processed in computer to identify and locate the intruder, to determine velocity and mass of the intruder and the direction in which he moves.

Performance:

• Sensitivity: 0.01 mG,
• Frequency range: 0.01 – 200 Hz
• Sensor dimensions: 40х25х10

 2. Fiber optic microphone.

   Highly sensitive compact fiber optic microphone can be used as a single acoustic logging unit or as a part of quasi-distributed system to localize noise sources within some territory.

Performance:

• Detectability: 10^-4 Pa
• Frequency range:  20 to 100 000 Hz

3. Fiber optic weather station. Provides complete and accurate information about weather conditions with high spatial resolution.

  Wind direction and wind speed detectors, atmospheric pressure, temperature and humidity sensors can be integrated into single meteo system. Thus, enabling communication of data from up to 100 autonomous sensor weather stations connected to one AC/battery powered registration unit, solar panels and wind generators via wireless/wire interface by means of single fiber optic lightwaves with up to 15 km length. These stations do not expend their own energy on data transmission and are based on optical reflection.  

Performance:

• Operation temperature:  -80°C to +120°С
• Atmospheric pressure: 0.1 kPa
• Temperature accuracy: 0.1 °С
• Relative humidity accuracy: 10%
• Wind speed accuracy: 10 м/c
• Wind direction accuracy: 2°

4. Temperature sensors operated in extreme conditions up to + 300^оС (+ 750^оС,  + 2000^оС)

Thermometry applications:

- at low pressure compressor stator and at compressor bladings;

- high voltage compressor combustion chamber;

- stationary units of combustion chamber (at augmenter).

5. Pressure sensors up to 6 kgf/cm2 (4kgf/cm2, 60 kgf/cm2).

Applications:

- radial legs of variable guide vane of gas turbine engine;

- substitution for existing flange pressure sensors (oil, gas);

- fuel trunk. Substitution for existing flange pressure sensors.

6. Strain gauging of blades with rotor removal.

7. Viration analysis of bearing collars, including composite collars.

8. Acoustic emission – various interferometric microphones, Bragg-grating accelerometers.

9. Air duct icing control.

10.Encoders of rotation angle of rotating devices and relocation of hydraulic power units.

 * - these solutions can be customized to meet specific technical requirement of the Customer.