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Fire Protection
PLEASE SCROLL DOWN TO SEE THE VARIOUS METHODS
CARBON DIOXIDE
Carbon Dioxide is a tried and trusted fire Protection concept, which basically dumps C02 into an area limiting any oxygen and suffocating any fire. The major disadvantage with this is the risk to human life, hence considerable effort has to be ensured in ensuring human evacuation before the dump occurs.
The following article "Carbon Dioxide – CO2 provides effective and reliable fire protection" gives a useful overview.
Halon fire-fighting systems were banned on new buildings
from July 1992 because of the
detrimental effects of CFC-based products on the ozone layer.
The principle of operation of the Hi-fog system is that the spray heads are all activated simultaneously to propel the small water droplets which have a greater surface area at very high momentum into the whole space which act to absorb the fire’s energy. The droplets vaporise almost completely, cooling the flames and forming steam that displaces the oxygen. The result is rapid and efficient and the extinguishing effect is combined with the cooling of the surrounding air, flue gases and surfaces to prevent re-ignition. Hi-fog’s sprinklers have a suction effect that draws in the gases, cools them and washes particles to the floor. The suction in the small sprinkler is 10m3/min and can be up to 25m3/min in the large.
Advantages of the Hi-fog system are:Disadvantages of the Hi-fog system are:
The name INERGEN is derived from a combination of INERTgas and nitrogen.
The composition of the gas "Inergen" (IG-541 or 52.40.08) is Nitrogen (52+/-4%), Argon (40+/-4%) and Carbon Dioxide (8+/1%) of which the concentration used is 35-50%.
The atmosphere consists of 21% Oxygen, 78% Nitrogen, 0.02% Carbon Dioxide and a variety of other gases.
When INERGEN is introduced into the atmosphere the resulting compositions are as follows:
66.5 to 70% Nitrogen
11.5 to 16.4% Oxygen
3.1 to 4.3% Carbon Dioxide
This resulting composition can extinguish fires caused by a wide range of flammable liquids, gases and solids. It achieves its effect by reducing the oxygen level.
The volume calculations of the protected areas are critical and hence it is recommended that they be double-checked to ensure accuracy.
INERGEN SYSTEMS are environmentally friendly and are very safe when sized correctly. People are still able to breathe in the reduced levels of Oxygen and exit the area without risk to their health. The reduced Oxygen level does not support combustion.
The disadvantages of INERGEN include that it should only be used for total flooding applications and that the enclosure around the fire hazard should be tight enough to hold the required concentration of Inergen for a period sufficient to extinguish a fire. In addition if a Halon system is being replaced the volume required is larger, hence the bottle storage area may become a problem.
See the article "Inergen is the world's leading fire suppression agent".
FM-200 is chemically known as heptafluropropane and is sometimes referred to as HFC-227ea. It is a colourless, liquefied compressed gas. It is stored as a liquid and dispensed into the hazard as an electrically non-conductive vapour. FM200 extinguishes fire by both its chemical effect (80%) and its physical effect (20%). It has been classified as being suitable for use as a total flooding agent in occupied areas.
FM200 is effective as a fire extinguishing agent for use on Class A surface fires, Class B flammable liquid fires and Class E electrical fires.
Although FM200 is considered non-toxic to humans in concentrations used for fighting fires certain safety considerations should be considered when handling and applying the agent.
| The major disadvantage of FM200 is that it decomposes to form halogen acids when exposed to open flames. The discharge from FM200 may create a hazard to personnel from the natural agent itself and from these products of decomposition that result when the agent is exposed to fire or other hot surfaces. Exposure to the agent is generally of less concern than the exposure to decomposition products, however both should be avoided. The formation of these acids is minimised by using early warning detection systems and proper system installation. |
PYROGEN
Pyrogen is described as being the world's first commercially available Aerosol Fire Extinquishing System get more information from: http://www.pyrogen.co.uk/downloads/PyroGen%20(2008)%20brochure.pdf
VERY EARLY SMOKE DETECTION
Very early smoke detection systems are used for the sensitive electronic detection of smoke. They are used as an early warning system.
A typical very early smoke detection system consists of five major components:
The sampling pipe or pipes are connected directly to a dust filter designed to remove particles greater than 25 microns in diameter. Dust particles greater than this size have been proved to be potentially troublesome and eliminated by filtering. When the air sample enters the detector chamber, it is exposed to an intense light flash from a Xenon lamp. An extremely sensitive photoelectronic receiver detects light scattered off particles suspended in the air stream. The resulting signal is amplified and processed to produce an analog reading of the smoke intensity. The steam of air is continuously refreshed.
Systems that use broad-spectrum light sources such as Xenon are much more sensitive in a much broader spectral bandwidth than those that rely on light emitting diodes. Xenon closely emulates the spectrum, the intensity of sunlight and it covers the complete spectrum. It extends well into the ultraviolet and deeply into the infrared. Therefore the detector can respond to particles of all sizes and it performs well for a wide range of possible fuels and throughout the stages of fire growth.
OTHER USEFUL INFORMATION
1.10
Fire
Protection adds Value to Offshore Project Planning - Larry Watrous -
The importance of fire protection in the design and construction of offshore
structures can be a critical factor in the success of today’s offshore oil and
gas projects. Integrating this component into the planning of a production
facility is taking on increasing importance. This article addresses the changing
needs and expectations, scope of equipment and services, and regulation in the
fire protection discipline, as well as the capabilities and roles of the fire
protection professional. The article further emphasizes the timing necessary for
implementing a formal fire protection program in the design and construction of
new offshore structures or the revamping of existing facilities, and the need
for the expertise of a trained fire protection engineer to be involved with the
development of all phases of these projects - from Mustang Engineering.
1.10Design
Engineering Key to Adequate Fire Protection - Larry Watrous -
This article has useful tips on the skills required of a Fire Protection
Engineer - from Mustang Engineering.
