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Smart Sensor Technology
for Gas Pipeline Monitoring
Hawk Measurement Systems
Fibre Optic Distributed Sensor
(FOS)
 The optical fibre cable is the sensor:
• The multiple core Fibre To The Home • The standard loose tube
telecommunication fibre cable could be
(FTTH) cable can be used as a
used as a temperature sensor.
distributed acoustic and strain sensor.
FOS
 The optical fibre cable is the sensor:
Sheath
Optical fibre
Adhesive tape
•
Loose tube
Ideal design integrates loose tube fibre (for temperature sensing),
tight buffered fibre (for strain and acoustic sensing) and adhesive tape
together in one cable, so it could stick to flat surface.
Distributed Acoustic Sensor
(DAS)
Leak sound signal location
Intensity (a.u.)
Intensity (a.u.)
Leak sound waveform
Position (m)
Detect leak position
Time (ms)
Detect leak hole size
DAS
 Third party interference detection:
Sound waveform
Intensity (a.u.)
Intensity (a.u.)
Sound signal location
Position (m)
Time (ms)
Performance Specifications for
DAS
Maximum fibre length
50 km
Spatial Resolution
0.5 m
Location accuracy
Within 5 m or better
Identify activities
Gas leak, Gas pressure and leak hole size, digging, normal vehicle, human
and animal passing etc.
Acoustic wave bandwidth
0 – 20 kHz distance pending
Real time detection
Yes
Two channel detection to minimize signal fading
Yes
Tolerance to single cable fault*
Yes
Fault Detection / Reporting
Programmable fault alarms and reports
Sensor Life Time
>30 years
Operating temperature range
Control unit size
Operating Voltage
Power consumption
* Both fibre ends need to be accessible (DAS2)
Control unit: +5 OC to +60 OC
Optical fibre cable: -30 OC to +70 OC
4U 19” rack enclosure
90 – 250 Vac
9-30 Vdc
<180 VA
Temperature Detection
(Joule-Thomson effect)
•
Leakage from a compressed gas line is identified by the development of a cold spot
due to the pressure release known as the Joule-Thomson effect. Typical JouleThomson effect figures for natural gas are -0.5°C/ bar x delta p which indicates that
small pressure changes result in significant temperature variations.
•
The pipeline outer surface being rapidly cooled by the Joule-Thomson effect, a
temperature gradient develops in the soil around the pipeline surface. The speed of
the temperature gradient development depends on the type of soil and may vary from
a few seconds to a few minutes.
•
The cooling effect is independent of the soil temperature and that the magnitude of the
cooling effect remains the same regardless of soil temperature.
Distributed Temperature Sensor
(DTS)
 Fibre optic sensor detection of temperature change over a
12m region:
Performance Specifications for
DTS
Maximum fibre length
50 km
Spatial Resolution
0.5 m
Location accuracy
Within 5 m or better
Temperature Resolution
0.1 C
Temperature Accuracy
±0.1C
Signal Averaging
1 to 16,000,000
Data collection time
1 to 30 seconds, dependent on distance, accuracy and
interrogation method.
Fault Detection / Reporting
Programmable fault alarms and reports
Sensor Life Time
>30 years
Control unit: +5 OC to +60 OC
Operating temperature range
Control unit size
Optical fibre cable: -30 OC to +70 OC
4U 19” rack enclosure
90 – 250 Vac
Operating Voltage
Power consumption
9-30 Vdc
<180 VA
Distributed Strain Sensor
(DSS)
Strain ()
130
80
30
-20
7570
7575
Distance (m)
•
The strain change at a pipe surface and deformation of a pipe could be
detected by optical fibre cable. Multiple cables can provide strain detail
along more than one axis.
7580
Performance Specifications for
DSS
Maximum fibre length
50 km
Spatial Resolution
0.5 m
Location accuracy
Within 5 m or better
Strain Resolution
2με
Strain Accuracy
± 2 με
Signal Averaging
1 to 16,000,000
Data collection time
1 to 30 seconds, dependent on distance, accuracy and interrogation method.
Fault Detection / Reporting
Programmable fault alarms and reports
Sensor Life Time
>30 years
Operating temperature range
Control unit size
Operating Voltage
Power consumption
Control unit: +5 OC to +60 OC
Optical fibre cable: -30 OC to +70 OC
4U 19” rack enclosure
90 – 250 Vac
9-30 Vdc
<180 VA
Multiple Parameter FOS
•
Combination of sound, temperature and strain detection minimizes the
chance of false alarm
DAS-Sound
DTS-Temperature
DSS-Strain
•
Fiber optic sensing can detect and localise leaks continuously and
accurately along the entire length of the pipeline.
•
It detects the signature of leak: Leak sound, cool spot due to leak and
strain change.
Fibre Optic Sensing
•
Distributed sensor can
continuously monitor vibration,
strain and temperature on pipe line
for the entire length of optical fibre.
•
Fibre optic cable is easy to install.
•
Fibre optic cable is passive –
No electrical power required.
•
Little or no maintenance required.
•
Fibre optic sensing has low cost.
•
Fiber optic sensor is weather independent without being compromised
by rain, fog etc, and not disturbed by moisture, dust or smog.
Scope of Monitoring
•
Vibration and sound of leak and third party intrusion
•
Temperature
•
Stress, strain along tensile members and cables attached to pipeline
•
Emergence of pipe deformation
•
Loss of ground support due to soil erosion
HAWK Fibre Optic Sensor
(HAWK FOS)
•
HAWK fibre optic sensing data collection
system compares outputs from multiple
technologies to improve sensing reliability
and discriminate against false positives.
•
Advanced cable design improves
sensitivity of both temperature and strain
measurement.
•
Enhanced acoustic sensing technology
virtually eliminates signal fading.
•
Simple filtering and performance
enhancement software.
Thank You!