Halon Systems Ch. 5, pages HALogenated hydrocarbON not the same as halogen F, Cl, Br, I 1940’s ’s extremely effective

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

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

Montreal Protocol 1987 agreement between 24 countries phase-out production by 1994

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

Halon Replacements next chapter clean agents drop-in replacement didn’t happen greater concentration required greater storage volume less effective

Halon Types and Composition Major use in WW II aircraft engines, fuel tanks

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

Numbering System Halon 130l CBrF 3 1 carbon 3 fluorine 0 chlorine 1 bromine

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

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

Properties of Halon 1301 Flooding agent low design concentration (5-7%) harmless to equipment –non-corrosive –no residue relatively harmless to occupants

Properties of Halon 1301 continued Personnel Considerations no flame no products of combustion exposure 5-7 % OK if over 10% problems

Properties of Halon 1301 continued Products of Decomposition halons decompose with heat produce halogen acids HF, HBr, HCl very harmful

Properties of Halon 1301 continued Recommended Safety Features continuous alarm SCBA many exits signs training time delay

Design of Halon 1301 systems Storage liquified gas nitrogen gas as propellant 2 phase flow in piping vapour discharge

Design of Halon 1301 systems Types of systems 1301 for total flood [5-7% ] class A, B. C

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

Design of Halon 1301 systems Calculate room volume L x W x H may deduct volume of solid objects

Design of Halon 1301 systems Calculation of Specific Volume (s) volume of Halon/mass ft 3 /lb s = x T T = room temperature (F)

Design of Halon 1301 systems Correction for altitude if over 3,000 ft see table 5-4

Design of Halon 1301 systems Calculation of quantity (W) W = V x C x A (s) x (100-C)

Design of Halon 1301 systems W = weight of halon (lb) V = room volume (ft 3 ) s = specific volume of halon (ft 3 / lb) C = design concentration (%) A = altitude correction factor

Design of Halon 1301 systems Other factors extended discharge for leaky room normal discharge within 10 seconds minimize openings