1. Explosion Suppression
NFPA 69
initially for aircraft fuel tanks (1940’s)
industrially (1950’s)
to protect enclosed vessels/containers
often against dust explosions

2. Explosion Suppression
Detonations
fuel that contains own oxidizer
high explosive
munitions etc.
velocity of flame front > speed of sound
explosion suppression won’t work

3. Explosion Suppression
Deflagrations
fuel oxidant mix
velocity of flame front < speed of sound
black powder,
dust explosions
gas leaks
suppression is possible

4. Explosion Suppression
Alternatives or Enhancements
control oxidant concentration (inert gas)
control fuel concentration (ventilation)
stronger containers
explosion relief venting
process isolation

5. Explosion Suppression
How explosion suppression agents work
agent introduce early
absorb energy, or
inhibit chain reactions, or
dilute reactants
see fig. 9-1

6. Explosion Suppression Components
Container
refillable
pressurized with N2
mounted directly on vessel (no piping)
usually multiple containers

7. Explosion Suppression Components
Detection system
Ultra Violet (flame)
rate of rise pressure
Products of combustion
Infra Red (heat)

8. Explosion Suppression Components
Control panel
can handle multiple systems
nothing unusual

9. Explosion Suppression
Applications
aerosol fill rooms
grain handling
coal handling
other dusts

10. Explosion Suppression
Sequence
1. Mixture ignites
2. Pressure rised
3. Detector senses change, notifies panel
4. Panel initiates discharge, closes isolation valves
5. Flame front halted

11. Explosion Suppression
6. Deflagration extinguished
7. Suppression ceases
8. Agent replaced, system back in service