Halon Systems

1
Halon Systems

• Ch. 5, pages 88-99
• HALogenated hydrocarbON
• not the same as halogen
• F, Cl, Br, I
• 1940s - 1980s
• extremely effective

2
Halon Systems

• gaseous agent
• worked at low concentrations (6-12)
• stored as liquified gas
• relatively non-toxic
• blocked branching chain reaction
• class A, B, C

3
Halon Systems

• Chemicals that harm ozone layer
• CFCs
• ozone depleters
• phased out for environmental concern

4
Montreal Protocol

• 1987
• agreement between 24 countries
• phase-out production by 1994

5
Exisiting Halon Systems

• Still legal
• Halon bank for decommissioned agent
• refill possible
• many have duplicate protection
• remove upon discharge

6
Halon Replacements

• next chapter
• clean agents
• drop-in replacement
• didnt happen
• greater concentration required
• greater storage volume
• less effective

7
Halon Types and Composition

• Major use in WW II
• aircraft engines, fuel tanks

8
Numbering System

• 1st, carbon atoms
• 2nd fluorine atoms
• 3rd chlorine atoms
• 4th bromine
• 5th iodine

9
Numbering System

• Halon 130l
• CBrF3
• 1 carbon
• 3 fluorine
• 0 chlorine
• 1 bromine

10
Streaming agents

• Halon 1211
• gas at room temperature
• stored as liquified gas
• BP 25 F
• projected as stream
• portable extinguishers

11
Flooding agents

• Halon 1301
• gas at room temperature
• stored as liquified gas
• BP -70 F
• rapid vapourization
• flooding systems
• computer rooms

12
Properties of Halon 1301

• Flooding agent
• low design concentration (5-7)
• harmless to equipment
• non-corrosive
• no residue
• relatively harmless to occupants

13
Properties of Halon 1301 continued

• Personnel Considerations
• no flame
• no products of combustion
• exposure 5-7
• OK
• if over 10
• problems

14
Properties of Halon 1301 continued

• Products of Decomposition
• halons decompose with heat
• produce halogen acids
• HF, HBr, HCl
• very harmful

15
Properties of Halon 1301 continued

• Recommended Safety Features
• continuous alarm
• SCBA
• many exits
• signs
• training
• time delay

16
Design of Halon 1301 systems

• Storage
• liquified gas
• nitrogen gas as propellant
• 2 phase flow in piping
• vapour discharge

17
Design of Halon 1301 systems

• Types of systems
• 1301 for total flood
• 5-7
• class A, B. C

18
Design of Halon 1301 systems

• Selection of Design Concentration
• for inerting
• minimum 5
• for flame extinguishment (surface)
• 5-8
• deep seated fire
• higher conc.
• longer holding time

19
Design of Halon 1301 systems

• Calculate room volume
• L x W x H
• may deduct volume of solid objects

20
Design of Halon 1301 systems

• Calculation of Specific Volume (s)
• volume of Halon/mass
• ft3/lb
• s 2.2062 0.005046 x T
• T room temperature (F)

21
Design of Halon 1301 systems

• Correction for altitude
• if over 3,000 ft
• see table 5-4

22
Design of Halon 1301 systems

• Calculation of quantity (W)
• W V x C x A
• (s) x (100-C)

23
Design of Halon 1301 systems

• W weight of halon (lb)
• V room volume (ft3)
• s specific volume of halon (ft3/ lb)
• C design concentration ()
• A altitude correction factor

24
Design of Halon 1301 systems

• Other factors
• extended discharge for leaky room
• normal discharge within 10 seconds
• minimize openings