1. CXS490 Chemical Extinguishing System Halocarbon Extinguishing System

2. History Halons 1910, carbon tetrachloride started
to be used in a “glass grenade
("Pyrene") as an extinguishing agent.
Due to its toxicity and a number of accidents related to its use, agent was prohibited as a fire extinguishant in the late 50's.
1930, (same "family"), methyl bromide (CH3Br) began use as extinguishing agent, but due to toxicity, its use as extinguishing agent has been discontinued.

3. History Halons Since about 1960, the two agents widely used
Halon 1301 & Halon 1211
become more & more
popular for applications
until the Montreal Protocol
(the international agreement to protect ozone layer) stopped production in 1994 of halons & later of other ozone depleting substances.

4. Halon Nomenclature System
Naming Convention
Halon system for naming halogenated hydrocarbons was devised by U.S. Army Corps of Engineers to provide a convenient and quick means of reference to candidate fire extinguishing agents.
First digit (number) represents number of carbon atoms
in compound molecule;
Second digit represents number of fluorine atoms;
Third digit represents number of chlorine atoms;
Fourth digit represents number of bromine atoms; and
Fifth digit represents the number of iodine atoms.
In this system, terminal digits, if equal to zero, are not expressed.

5. Halon Nomenclature System
Naming Convention F
Halon F C Br Bromotrifluoromethane
CF3Br F
Halon F
CF2ClBr Cl C Br Bromochlorodifluoromethane
F F
Halon Br C C Br Dibromotetrafluoroethane
C2F4Br2 F F
Discuss - Carbon Tetrachloride (CCl4) &
Methyl bromide (CH3Br)

6. Human Exposure Halon 1301 Exposure Limits
Original Concentration Guidelines:
up to 7%: < 15 minutes exposure
7 to 10%: < 1 minute exposure
(inhalation)
%: < 30 seconds
> 15%: prevent inhalation exposure
Current Guidelines:
NOAEL (Volume %) - 5%
LOAEL (Volume %) - 7.5%
Maximum Permitted Human Exposure for 5 minutes - 5%
NOAEL - No Observable Adverse Effect Level
LOAEL - Lowest Observed Adverse Effect Level

7. Halon 1301 Physical Properties
Halon Properties
Boiling Point °F
Boiling Point °C - 58
Specific Volume x t (Ft3/lbs) (t is °F)
Specific Volume x t (M3/Kg) (t is °C)
Vapour Pressure 199 psig
@70°F SV k1 k2

8. Halon Extinguishment Mechanism
Extinguishing Mechanism
The mechanism by which halons extinguish fire is not completely understood.
However, it has been established that these products act by "breaking" the chemical flame chain reaction.
Chain Breaking ~ 80 %
Cooling ~ 20 %
Secondary
Primary

9. Halon 1301 Minimum Design Concentrations
Halon Design Concentration
Surface fires associated with the burning of solid material: 5%
Other Fuels
Flame
Extinguishment Inerting
Fuels (% by Volume) (% by volume)
Acetone
Benzene
Ethylene
Propane
Methane
Where the possibility of achieving an explosive concentration of the fuel exits, the “Inerting Concentration” must be used.

10. Discharge Duration 10 seconds To reduce increase of fire size &
the resultant generation of
HF and HBr
True for Halocarbons & Halons

11. Halon 1301 and the Environment
Montreal Protocol
CFC's and halons destroy the stratospheric ozone that protects the earth from damaging ultraviolet radiation.
An international agreement - the Montreal Protocol - was signed in September 1987 and was subsequently amended to require a phase-out of halon production in developed countries on January 1, 1994.
This environmental problem has had a major impact on the use of halons.
No substitute is available at present that offers a “drop in replacement” (same space and weight advantages) required for applications such as on-board aircraft systems or use within the crew compartments of military tactical vehicle.

12. Halon Standard Halon 1301 Design Standard
NFPA 12A is the applicable design standard for Halon 1301 systems.

13. New Technology Halocarbon Agents
New technology halogenated agents do not contain bromine or chlorine and are fluorocarbons. Fires extinguished by the cooling action required to fracture fluorocarbon molecule. Less efficient on a weight/space basis than halon 1301 and when exposed to fire they produce greater quantities of hydrogen fluoride (HF) than halon 1301 did.
Stored in equipment that is similar to that used for halon 1301 systems, however flow rates are required to be slightly higher to accomplish discharge within 10 seconds.
Where the possibility of achieving an explosive concentration of the fuel exits, the “Inerting Concentration” must be used

14. Halon Extinguishment Mechanism
Halocarbon Extinguishing Mechanism
The mechanism by which halocarbons extinguish fire is:
Cooling ~ 80 %
Chain Breaking ~ 20 %
Primary
Secondary

15. Halocarbon Extinguishing Agents
HALOCARBON DESIGN FACTORS - Specific Volume (Sv) Factors (*1)
Generic
Trade k1 k2
Standard
Name
Imperial units
SI units
(ISO)
(ft3/lb)
(m3/kg)
Halon 1301
2.2062
0.1478
HFC-23 (*1)
FE-13
4.7302
0.3164
0.0012
HFC-125 (*1)
FE-25
2.722
0.1825
HFC-227ea (*1)
FM 200
0.1269
HFC-236fa (*1)
FE-36
2.0978
0.1413
0.0006
FK (*1)
Novec-1230
0.9856
0.0664

16. Halocarbon Extinguishing Agents - Design
This table illustrates the various required
design concentrations required (compared to halon 1301).
HALOCARBON
DESIGN FACTORS -
Design
Concentrations
(*1)
Generic Name
Trade Name
Minimum Class A Design Concentration Volume % (*2)
Minimum Class B Design Concentration Volume % (*2)
Inerting Concentration Methane/Air Volume % (#2)
ISO
Standard
Halon 1301 5
4.9 *
HFC-23 (*1)
FE-13
16.2
16.4
22.2
HFC-125 (*1)
FE-25
11.2
12.1 -
HFC-227ea (*1)
FM 200
8.5
9.0
8.8
HFC-236fa (*1)
FE-36
9.8
FK (*1)
Novec-1230
5.3
5.9

17. Halocarbon Exposure NOAEL - No Observable Adverse Effect Level
DESIGN FACTORS -
Design
Concentrations
(*1)
Generic Name
Trade Name
NOAEL
Volume
% (*3)
LOAEL
Volume %
(*3)
Maximum Permitted Human Exposure Concentration for 5 minutes (Occupied Areas) Volume % (*4)
ISO
Standard
Halon 1301 5
7.5 *
HFC-23 (*1)
FE-13 30
>50
HFC-125 (*1)
FE-25 10
HFC-227ea (*1)
FM 200 9
10.5
HFC-236fa (*1)
FE-36 15
12.5
FK (*1)
Novec-1230
>10
NOAEL - No Observable Adverse Effect Level
LOAEL - Lowest Observed Adverse Effect Level
All halocarbon agents have a maximum discharge time is 10 seconds to minimize unwanted production of hydrogen fluoride from flame contact by the agent.

18. Halocarbon Environmental
New halocarbon agents do not pose
a threat to Stratospheric Ozone Layer.
Many have long atmospheric lifetimes and
high global warming potential.
All, except FK are substances included in the Kyoto Protocol on Climate Change.
HALOCARBON ENVIRONMENTAL FACTORS
Generic Name
Trade Name
Ozone Depletion Potential
Global Warming Potential (100 year)
Atmospheric Lifetime (years)
Halon 1301 10
6,900 65
HFC-23 (*1)
FE-13
12,000
260
HFC-125 (*1)
FE-25
3,400 29
HFC-227ea (*1)
FM 200
3,500 33
HFC-236fa (*1)
FE-36
9,400
220
FK (*1)
Novec-1230 1
0.01

19. Halocarbon Technical Standards
ISO and relevant sub-parts. ISO is not applicable to explosion suppression. ISO is not intended to indicate approval of the extinguishants listed therein by the appropriate authorities, as other extinguishants may be equally acceptable.

20. Halocarbon Technical Standards
ISO specifies requirements and gives recommendations for the design, installation, testing, maintenance and safety of gaseous fire fighting systems in buildings, plant or other structures, and the characteristics of the various extinguishants and types of fire for which they are a suitable extinguishing medium.
It covers total flooding systems primarily related to buildings, plant and other specific applications, utilizing electrically non-conducting gaseous fire extinguishants that do not leave a residue after discharge and for which there are sufficient data currently available to enable validation of performance and safety characteristics by an appropriate independent authority.

21. Halocarbon Technical Standards
CO2 is not included as it is covered by other International Standards.

22. Halocarbon Technical Standards
All Gaseous system fire suppression NFPA standards assume the use of the standard by someone experienced in that area.

23. Halocarbon Technical Standards - NFPA 2001
Agents in standard were introduced in response to international restrictions on the of certain halon fire extinguishing agents under the Montreal Protocol signed September 16, 1987, as amended.
Standard is prepared for the use and guidance of those charged with purchasing, designing, installing, testing, inspecting, approving, listing, operating, and maintaining engineered (only) clean agent extinguishing systems, so that such equipment will function as intended throughout its life.

24. Halocarbon Technical Standards - NFPA 2001
Standard is intended to not restrict new technologies or alternate arrangements provided the level of safety prescribed by this standard is not lowered.
NFPA 2001 does not provide all the necessary criteria for the implementation of a total flooding clean agent fire extinguishing system. Technology in this area is under constant development, and this will be reflected in revisions to this standard. The user of this standard must recognize the complexity of clean agent fire extinguishing systems. Therefore, the designer is cautioned that the standard is not a design handbook.

25. Halocarbon Technical Standards - NFPA 2001
Standard on Clean Agent Fire Extinguishing Systems, is available to Seneca students by following the link to the Seneca Library from the My Seneca home page.

26. Halocarbon Systems General Requirements
Halocarbon extinguishing systems are generally of the total flooding type. The commonly used halocarbons vapourize and mix with air very efficiently making them ideal total flooding agents.
However these same characteristics make them generally unsuitable for use in local application type systems.

27. Halocarbon Systems General Requirements
Total flooding halocarbon systems
Total flooding systems may be used where there is a fixed enclosure about the hazard that is adequate to enable the required concentration to be built up and maintained for the required period of time to ensure the effective extinguishment of the fire.

28. Halocarbon Systems General Requirements
Two types:
1. Modular systems (agent storage at point of discharge)
Usually employs spherical containers connected to a maximum of four nozzles by short length of pipe. Often use explosive squibs for agent release (for valve opening). Different sizes of containers may be used in a single hazard
2. Central Storage Piped Systems
Uses cylinders of equal size, containing equal weight of halon. These cylinders are piped to a manifold, with check valve at each manifold inlet connection.

29. Design of Halocarbon Systems
The following elements have to be taken into account in the design of a halocarbon system: (refer to NFPA 12A for halon 1301 and NFPA 2001 or ISO for new technology halocarbon extinguishing systems)
1. Configuration of the hazard: dimensions (area, height, volume) of the hazard, nature of the separation before the risk and the surroundings areas. Volume used as a based for the computation of the quantity of agent, the nature of the enclosure will determine the extent of the protection (all areas that may be involved in a single fire incident must be simultaneously protected)

30. Design of Halocarbon Systems
2. Hazard ventilation: ventilation systems should be
automatically shut down upon system actuation.
3. Hazard fuels : fuel involved in the hazard must
be identified in order to determine the minimum
required concentration.

31. Design of Halocarbon Systems
4. Hazard temperature range: From a given quantity of agent, the concentration that will be achieved in a given volume will vary with temperature in this volume. The lowest temperature is used to calculate minimum amount of agent needed to obtain the required concentration.
The highest hazard temperature is used to verify that the maximum possible concentration that could be obtained is still acceptable for personnel safety.

32. Design of Halocarbon Systems
5. Specific Volume: The specific volume is calculated using
the following formula:
Sv units are m3/kg or ft3/lb
T is temperature in OC or OF

33. Design of Halocarbon Systems
6. Agent quantity: The required agent quantity is
calculated using the following mass formula:
Mass flooding formula:
where WLT = weight of halon
V = enclosure volume
C = Concentration
SvLT = specific volume

34. Design of Halocarbon Systems
7. Agent Concentration: The resulting agent concentration
calculated using the calculated weight from lowest
temperature and the specific volume from highest
temperature.
NOT REQUIRED IF NO TEMPERATURE VARIATION!
where C = Concentration
WLT = weight of halon
V = enclosure volume
SvHT = specific volume

35. Design of Halocarbon Systems
8. Maximum discharge time : 10 seconds
9. Size of piping, # of nozzles, etc.: according to manufacturers' listed manual & computerized calculation programs

36. Design of Halocarbon Systems
10. Detection and control:
A) Computer Rooms, Control Rooms,
Telecommunications Facilities,
Transformer vaults, etc.
Facilities often utilize high air change rates using conditioned air. High air flow rates and chilled fresh air make it difficult to utilize heat detection as the sole means of fire detection to cause release of the halon. More often smoke detection devices are used.

37. Design of Halocarbon Systems
In some cases, alarm from one such device will provide warning to occupants and cause shut-down of air handling systems.
Alarm from a second device of the same or similar type results in automatic release of halocarbon.
In other cases, heat detectors are
used as a second stage detection
means and automatic release only
occurs when a heat detection device
has responded.

38. Design of Halocarbon Systems
Abort switches, when used, should be
of “dead-man” type and installed only
within the protected area.
Manual pull stations should always be
capable of overriding operation of
abort stations.
One manual release station should be
located outside of the protected enclosure.

39. Design of Halocarbon Systems
B) Hazards that include flammable liquids or gases
Detection devices should be of either the explosion proof type or be intrinsically safe.
Heat detection devices or optical flame detection type devices are most often used for fire detection in these applications.

40. Design of Halocarbon Systems
It is not necessary that the control equipment and halon system be of the same manufacturer, however, both the NFPA 12A standard and the NFPA 2001 standard requires that the control equipment and releasing devices are compatible and that evidence of compatibility is provided.

41. Halocarbon Calculation
Space with dimensions of
11.43 m long by m wide
by 2.72 m high is to be
protected by Novec 1230.
The operating temperature range is 10 to 40OC.
Determine the required amount of agent and whether it is safe. 

42. Halocarbon Calculation
Determine necessary data input for agent
k = (p 14)
k = (p14)
c = % (p 15)
NOAEL = (p 16)
LOAEL = > (p 16)
5 Minute Exposure = (p16)

43. Halocarbon Calculation Weight

44. Halocarbon Calculation Concentration
Is it safe?
Yes (why?).
Less than the 10% (NOAEL & 5 minute human exposure)!

45. Design of Halocarbon Systems
Plans shall be to an indicated scale and reproducible.
Sufficient detail to enable an evaluation of hazard and the effectiveness of system. They shall show a detail of the material involved in the hazard enclosure.

46. Design of Halocarbon Systems
Plan Details of system shall include:
information and calculations on amount of halon 1301
container storage pressure,
internal volume of the container(s) ,
location type and flow rate of each nozzle
(including equivalent orifice area)
location, size and equivalent length of pipe, fittings and hose
location of the storage containers
location and function of detection devices
Auxiliary equipment and
Electrical circuitry (if used).

47. Design of Halocarbon Systems Acceptance Test
For new technology halocarbon agents
refer to either NFPA 2001 or
ISO
For halon 1301
Refer to NFPA 12A.

48. Maintenance of Halocarbon Systems
Inspection & Testing
Annual: Complete inspection of system & non-destructive test
Semi-Annual: Check agent quantity and pressure
Every 5 Years: Hydrostatic test of all hoses
Frequency Approved schedule level: Visual inspection
It is also important to identify any change to the protected space, such as, reconfigured layout, added ventilation, etc. to ensure that installed system remains adequate for protected space.