Applications of Gas Chromatography and Optical Fiber Sensors in Electrical Engineering

3.  Used in analytical chemistry, Gas
Chromatography is used to separate
and analyze compounds that vaporize
without decomposition.
 It can be further classified into
› Gas-Liquid Chromatography
› Gas-Solid Chromatography

4. It can be used to test the
purity of particular
substance.
To separate the different
components of a mixture.

5. Gas-Liquid Chromatography
(GLC)
Gas-Solid Chromatography
(GSC)
Uses the principle of partition. Uses the principle of
adsorption.
GLC employs liquid as the
stationary medium.
GSC employs a solid as the
stationary medium.
Retention Time is shorter. Retention Time is longer.
GLC uses capillary Columns. GSC uses packed columns.

7. The main components of GC are:
 Carrier Gas: He, H2, N2, Argon
 Sample Injection Port
 Columns/GC column
 Detectors
› Flame Ionization Detector (FID)
› Flame Photometric Detector (FPD)
› Thermal Conductivity (TCD)
› Electron Capture Detector (ECD)

8.  The cylindrical gas tank is fitted with a
› A pressure gauge: that indicates the
pressure
› Pressure controller: to control the
pressure of gas.
› A molecular sieve: To transfer filtered
dry gas. It removes water and other
impurities.
› Flow Regulator: To ensure a constant
flow rate of mobile phase to column.

9. Sampling Unit/Injection Port is attached to
the column head.
The injection of the sample is done using
› Split less injectors
› Split injectors
› On column injectors
› Automatic injectors

10.  Employed in different shapes and sizes.
U-type and helix coil type are such two
types of columns.
 They are classified into two types:
› Packed and
› Capillary
Columns are usually made up of
glass/fused-silica or rigid metal.

11.  Several detectors can be used in Gas
Chromatography or GC.
 Most used detectors in GC are listed
below:
› FID (Flame Ionization Detectors)
› TCD (Thermal Conductivity Detector)
› ECD (Electron Capture Detector)

12. 1
• Vaporizing a sample and injecting it onto
the head of chromatographic column.
2
• This sample then moves through the
column by the gas in the mobile phase or
carrier gas.
3
• The gases used in GC are usually inert.
Nitrogen, Helium and Hydrogen are some
examples of it.

13. 4
• For separation to occur, the GC column
contains a stationary phase.
5
• The stationary phase may be a solid or a
liquid.
6
• Depending on whether the stationary phase is a solid or a
liquid at its operating temperature, GC is classified
as gas–solid chromatography (GSC) or gas–liquid
chromatography (GLC).

14. 7
• Separation occurs because sample
components partition between the stationary
phase and the mobile phase (carrier gas).
8
• The sample traverses through the
Chromatographic column with the help of the
inert gas chosen.
9
• The components are recorded as a sequence of
peaks as they leave the column.

15.  It deals with both stationary and mobile
phase.
 In mobile phase components of the
sample are drawn to the stationary
phase and enter the stationary phase at
different rate of time.
 The different components of the sample
reach the stationary phase at different
time, thus reach the detector at
different time, which produces a series
of peaks along a time sequence.

16.  The peaks are then analyzed further to
determine the exact components in the
sample.
 The number of components in a sample
are determined by the number of peaks.
 The amount of a particular component is
determined by the area under the peak.
 The identity of the components can be
identified by the retention time*

18.  The Analysis is Completed in a short time
frame.
 The sensitivity of the method is quite high
 The Technique can be used to separate
complex mixtures.
 Good Precision and Accuracy
 The cost of the instrument is quite low
 Longer life of the equipment

19. Some practical applications of Gas
Chromatograph include:
 Analysis of drug products like antibiotics,
antivirals, anesthetics, sedatives.
 Analysis of dairy products like milk,
butter, for detection of milk sugars, fatty
acids.
 Gas chromatography for food quality
evaluation.

20.  The foremost advantage of gas
chromatography is to analyze the
transformer oil as the oil used mostly
contains hydrocarbons.
 In transformer oil analysis, the
technique is used to determine the
concentrations of dissolved gases within
the oil sample.
 The analysis of dissolved gases can be
used with gas analysis or other methods
to evaluate faults within a transformer.

21.  The DGA procedure consists of sampling
of oil from the transformer, extracting of
gases from the oil and analysis of the
extracted gas mixture in a gas
chromatograph (GC).
 Composition of key gases indicates
particular problem (i.e. presence of H2)
indicate partial discharges (PD).
 Co2: Cellulose insulation degradation.

22.  Process Gas Chromatograph-MAXUM
Edition II by SIEMENS-Brochure

23. Buck Scientific
• Cost: 11lacs
ABB
• Cost: 15lacs
Agilent Technologies
• Cost:Rs18 -26lacs
Thermo Fisher Scientific
• Cost:Rs. 10lacs

25.  Optical Fiber Sensors employ optical
fiber as the sensing element or relaying
signals to the electronic device to process
them further.
 These are used to sense quantities like
temperature, pressure, vibrations,
displacements, etc.
 Optical Fibers can be classified as follows
› Intrinsic Sensors
› Extrinsic Sensors

26. In an intrinsic fiber optic sensor one or more of the physical
properties of the fiber undergo a change .
In an extrinsic fiber optic sensor the fiber is simply used to carry
light to and from an external optical device where the sensing takes
place.
The fiber just acts as a means of getting the light to the
sensing location.
Perturbations act on the fiber and the fiber in turn changes some
characteristic of the light
Intrinsic Sensors
Extrinsic Sensors

28. The core of the optical fiber are divided into
the following types:
 Plastic Type
 Glass Type

30. It consists of an
 Optical source (Laser, LED, Laser diode
etc),
 Optical fiber,
 Sensing or modulator element (which
transduces the measurand to an optical
signal),
 An optical detector and
 Processing electronics (oscilloscope,
optical spectrum analyzer etc).

31.  Fiber optic sensors work based on the
principle that light from a laser or any
super luminescent source is transmitted
via an optical fiber, experiences changes
in its parameters in the optical fiber and
reaches a detector which measures these
changes.

32.  The optical fiber consists of the core and
the cladding, which have different
refractive indexes.
 The light beam travels through the core
by repeatedly bouncing off the wall of the
cladding.
 The light beam, having passed through
the fiber without any loss in light
quantity, is dispersed at an angle of
approximately 60° and emitted to the
target.

34.  Measurement of physical properties
such as temperature, displacement,
velocity, strain in structures of any size
or any shape.
 In real time, monitoring the physical
structure of health.
 Buildings and bridges, tunnels, Dams,
heritage structures.
 Night vision camera, electronic security
systems, Partial discharge detection
and measuring wheel loads of vehicles.

35.  Fiber optic sensors are used in power
transformers for an on-line and real-time
monitoring.
 As they are small in size and lightweight
they offer an advantage of such as
immunity against electromagnetic
interferences, high-sensitivity,
reliability, stability, durability, against
extreme environments and fast response.

36. The different manufactures/suppliers are
as listed below:
FBGS
• Cost:Rs. 10,000-25000
Omcron
• Cost:Rs. 35,000
• Detection Range: 4000mm
• Fiber Optic Type : Plastic

37. Banner
• Cost:Rs19,000
• Detection Range:2000 mm
• Fiber Optic Type : Plastic
Banner
• Cost:Rs12,000
• Detection Range:2000 mm
• Fiber Optic Type : Glass