Fire and Gas Detection System Requirements for the Oil and Gas Industry. Offshore Platforms are also applicable for onshore plants/terminals. Safeguarding and Protective System to ensure oil and gas facilities are safe to operate.

1. Fire and Gas Detection System
(Offshore Facilities)
(Part 1 : The Field Devices and Its Panels)
Chun Chet Gan (Ir.)
MSc Operations Management
[Manchester School Management]
University of Manchester Institute of Science and Technology (UMIST),
United Kingdom.
BEng (Hons) Mechanical Engineering
[Simon Building]
University of Manchester, United Kingdom

2. The Purpose of Fire and Gas Detection
• The purpose of Fire and Gas Detection System, with the detectors located at
outdoor and indoor areas of the platform, is to protect the platform from a gas leak
or a fire. These areas are segregated into two (2) areas:-
1) outdoor, and
2) indoor areas.
• Outdoor areas are zoned into hazard open process or non hazard utility areas.
• Enclosed rooms are indoor areas (inside a closed structure or a building).

3. The Detection Area – Outdoor and Indoor
• In general, process areas (outdoor) are highly hazardous. It contains hydrocarbon
inventories and these areas are regarded as hazard areas on the platform. The
classification of these hazardous areas are defined by Safety.
- Hazard equipment are vessels, pumps, hydrocarbon pipelines, turbine generators,
etc.
• Utilities areas (are considered as outdoor areas) are non-hazardous zones of a
platform.
- Example of equipment in these areas are firewater pumps, diesel tanks, instrument
air compressors.
- Others equipment like water storage tank, sewage macerator, etc. are also
regarded as non-hazardous area.
• Indoor areas are safe areas on the platform.
• Example of these areas are:
- Control Room,
- Switchgear Room,
- Motor Control Centre MCC
• However, battery rooms are hazardous areas.

4. Fire and Gas Detection System in Two Parts
- Field Devices and Control Panels
• The detection system is segregated into two parts. These are:-
1) Field Devices - located outside in the process areas, utility areas or inside rooms,
and
2) Control Panels – these are logic solvers (or programmable logic controllers PLC,
addressable controllers), with graphic screens, to perform the required functions
(alarm and shutdown) in case of a detection.
• The following are pictures of fire and gas detectors and detection panels.

5. • Flame detectors
– Ultraviolet (UV)
– Ultraviolet and Infrared (UV/IR)
– Infrared (Triple IR)
Model X3301
(Triple IR)
Courtesy of DETRONICS
Model S251f+
(Triple IR)
Courtesy of THORN
Type of Field Devices
(this slide is from previous internal lecture)

6. • Smoke detectors
– Optical
– Ionization
(being phased out due to
!stringent! disposal requirements
of radioactive substances)
• Heat detectors
– rate of rise
– fixed
Model 601P
Smoke Detector
Model 601H-R Model 601H-F
Heat Detector
Courtesy of THORN
Type of Field Devices
(this slide is from previous internal lecture)

7. Type of Field Devices
(this slide is from previous internal lecture)
• Pneumatic fusible plugs
(pressure sensors will send a signal to
fire and gas system FGS upon
detection of low air pressure)
– Melt at 71 degree celsius
• Manual alarm callpoint
– Breakglass or pushbutton
Model SS-6-FTA-160
Fusible Plug
MODEL SM87 BG
MODEL SM87 PB
Courtesy of MEDC
Courtesy of SWAGELOK

8. Type of Field Devices
(this slide is from previous internal lecture)
• Gas detectors
– Infrared, electrochemical,
catalytic (point detectors)
– Infrared (line-of-sight)
Courtesy of DRAEGER
Model Polytron 2IR
Model Pulsar
Model Polytron FX
Model APEX
Model ECLIPSE
Courtesy of DETRONICS
Model OPECL
Courtesy of DETRONICS
Courtesy of SIEGER

9. Types of Fire and Gas Panel
(this slide is from previous internal lecture)
• Programmable Logic Controller (PLC based)
- Main Panel
- Addressable Panel
Model MINERVA
Courtesy of THORN
Courtesy of Honeywell
Model Honeywell Icon
Series Console MMI
Model Honeywell Fail
Safe
Controller (FSC)

10. ANIMATION OF A GAS LEAK
V-1
WIND
GD-1
GD-2
Tx
Rx

11. ANIMATION OF PLACING
FLAME DETECTORS
FD-1
FD-2
V-1
FD-3

12. ANIMATION OF A SHUTDOWN
GD
2oo3
GD
GD
&
Maintenance
Enabled
Reset w latched
Alarm
Shutdown

13. Principle of Gas Detection (1)
(this slide is from previous internal lecture)
100

14. Principle of Gas Detection (2)
• The principle of detection is based on absorption of infrared light by hydrocarbon
gas in the measurement chamber.
• For open path (or line-of-sight) gas detectors, the measurement area in between the
receiver and the transmitter unit is the hazardous area that required to be monitored
by these units. It is this area that this set of detectors are aligned diagonally across
or straight over the equipment. The unit of measurement is LEL.m or LFL.m
• LEL is the abbreviation for lower explosive limit whereas LFL is lower
flammability limit.
• LEL.m or LFL.m is the concentration of the gas cloud multiply by the distance
between the receiver and the transmitter unit.
- For example, if the gas cloud is 20 %LEL or %LFL, and the distance between the
receiver and the transmitter unit is 5 metres, then the measurement reading is about
20 %LEL x 5.0m = 1.0 LEL.m (0.20x5 = 1.0LEL.m). If the gas cloud is 60%LEL
and the distance is 5 metres, the reading is 60 %LEL x 5m = 3.0 LEL.m

15. Principle of Flame Detection (1)
(Ultraviolet & Infrared Wavelengths) (this slide is from previous internal
lecture)
Extracted from NFPA 72
recommended guide on Code of
Practice

16. Principle of Flame Detection (2)
• UV Flame Detector – This detector detects UV light source in a fire. UV light
source are found in hydrogen flame.
• UV/IR Flame Detector – This detector must detects both UV and IR light source
before this detector considers the target/detection area as a confirmed detection.
• Triple IR Flame Detector – This detector has three (3) infrared sensors. Infrared
light source are found in hydrocarbon flame.

17. Principle of Activation (1)
GD
FD
2ooN
Maintenance
Override
&
Alarm
or
Shutdown
Latched
Reset

18. Principle of Activation (2)
• The controller is either an electronic and pneumatic panel.
• The electronic panels are as below:
1) main panel (redundant/triplicated TMR),
2) addressable panel, and
3) instrument package panels (like turbine generators, firewater pumps, instrument
air compressor, etc.).
• 4) Others panels, shutdown panel or Public Address General Alarm PAGA panel
• Fire and gas signals to/from various panels (item 2 - 4) will be connected to the
main panel.
• Pneumatic panels (only pressure transmitter/switch signal connected to the PLC) is
a sub-system to the main panel.
• Also known as an electro/pneumatic panel (partial electronic), e.g. fusible plug
panel, deluge panel, etc., the instrument air is used to pressurized fusible tubes.

19. The Method of Detection of Field Detectors (1)
The principle of measurement/detection for field devices are:-
• Gas detectors (point HC or open path) – By infrared sensor(s). The concentrated
gas will block the light from reaching the sensor. The detection of an early warning
below the Lower Explosive Limits LEL will enable the controller to perform a
shutdown and sound the alarms.
• Flame detectors – A fire will be detected by the sensor (infrared wavelength). The
detector will detect a fire only after it develops.
• Manual call points – It is a detection by manual activation. The call points are
located at the edge of the platform or exit in the room visible to inhabitant of the
platform.
• Heat detectors – It detects the change in temperature rise (Rate-of-rise) or
temperature in exceed of a fixed setpoint in a room.
• Smoke detectors (optical) – Smoke particles in measurement chamber block light
from an internal source to the sensor. It detects smoke particles before a fire
develops.
• Fusible plugs – Melting of plugs at fixed elevated temperature due to heat. It is an
outdoor protection device.

20. The Method of Activation (1)
• Non-Fail Safe (i.e. an energized output on alarm/activation) - This non-fail safe
activation will activate output signals only if it is required to be activated.
(In normal practice, when the deluge valve is required to be activated, an output
signal will be sent to the solenoid that is part of the deluge valve).
• Fail Safe – otherwise, the fail safe outputs are de-energized on alarm/activation.
(If it is a fail safe application, the output signal will be deactivated when it is
required to perform a function. Example of this application is the fire and gas
outputs to a shutdown panel/system).
• Other applications like a fault signal, has to be supervised to ensure that this signal
is noticed when there is a failure in the panel.
• The detection system has to safe guard the platform from a gas leak or a fire. When
it occurs, the system must work.
• It is very unlikely that the redundant device fails when a shutdown is required.
Other means has to be sorted to ASSURE a safe operation.

21. The Methods of Detection of Electronic &
Pneumatic Panel (2)
• Electronic panels – are complete platform solution, with calculated failures (low
failure and with redundant I/Os and processors). It takes into account of redundant
failure(s), if it occurs.
• Pneumatic panels – has become a partial, but proven reliable solution due to its
depressurization mode. Air line leakages will bring the platform to a safe condition.

22. The Location of the Detectors
(and Its Application)
• The types of detectors and its recommended location are in the next slide.
• This table shows the type of detectors in the areas mentioned in the previous slides.
- Gas and flame detectors are mainly outdoor devices.
- Smoke and heat detectors are indoor devices.
- Manual call point can be located either in indoor and/or outdoor areas.
- Fusible Plugs are outdoor fire detection devices, location as per API RP 14C
guidelines.
(You can locate flame detectors inside a room if it is appropriate. However, smoke
and heat detectors are always located inside an enclosure(s).
• These are the devices to detect gas (early warning) or fire (either early warning or
after the fire is fully developed).

23. The Location of the Detectors
(and Its Application)
(this slide is from previous internal lecture)

24. The Location of the Panels
(and Its Application)
• The control panels are located either in the control room or outside in the open
areas.
• Electronic Panels with its redundant processors and safe failures have proven its use
on offshore platform, with proper design considerations.
• Pneumatic Panel, the oldest method, has is rigid and reliable (mechanically) method
of shutting down a platform.
• The detection system is connected to the deluge system (sometimes, not always) to
cool the equipment when the platform is undergoing depressurization through the
vent pipes.
• At the same time fire and gas signals from other system/panels will send signals to
the fire and gas detection panel for fault alarm or shutdown purposes.
(e.g. gas turbine panel upon detection of gas or fire will send signal to fire and gas
panel to close the fuel lines)

25. Part 1 : The Field Devices and Its
Panels
• End of Lesson 1
• Questions

26. Own Notes (1)
• Part 1 : The Field Devices and Its Panels
• The Purpose of Fire and Gas Detection
• The Detection Area – Outdoor and Indoor
• Fire and Gas Detection System in Two Parts - Field Devices and Control Panels
• Type of Field Devices
(this slide is from previous internal lecture)
• Types of Fire and Gas Panel
(this slide is from previous internal lecture)
• ANIMATION OF A GAS LEAK
• ANIMATION OF PLACING FLAME DETECTORS
• ANIMATION OF A SHUTDOWN

27. Own Notes (2)
• PRINCIPLES OF GAS DETECTION
(this slide is from previous internal lecture)
• PRINCIPLES OF FLAME DETECTION
(Ultraviolet & Infrared Wavelengths) (this slide is from previous internal
lecture)
• PRINCIPLE OF AN ACTIVATION
• The Method of Detection of Field Detectors
• The Methods of Activation (Detection of Electronic & Pneumatic Panel)
• The Location of the Detectors
(and Its Application)
(this slide is from previous internal lecture)
• The Location of the Panels
(and Its Application)