Chapter 28 Class B fires Flashcards
USDOT AND TDG FLammable liquid range
nfpa and whimis
- 5 degrees c
37. 8 degrees c
fires in open topped tanks?
boilover
slop over
froth over
Fire and explosion prevention
Exclusion of ignition sources
exclusion of air
storage of liquids in closed containers or systems
Use of inert gas atmosphere instead of air
ventilation to prevent accumulation of vapor within the flammable range
extinguishment of ignitibal eliquid fires
shutting off the fuel supply
cooling the liquid to stop evaporation
excluding air by various means
a combination of these methods
pressurized gas characteristics
Pressure diffusivity (trendency to spread freely) low boiling point colorless and/or odorless creates static electicity when flowing
safety relief valves
safety or pressure relief valves
rupture disc
fusible plug
manual control valves
hand wheel
stem valve
gas cylinder color coding
Green/silver - o2 blue - nitrous oxide orange - cyclopropane brown - helium red - ethylene grey - carbon dioxide
release of contents
3 stresses
and 9 container breachs
thermal
mechanical
chemical
attachments open up disintergration detonation puncture runaway cracking rapid relief spill/leak split/tear violent rupture
3 types of containers - pressure vessels
cylinders, lines, tanks
LPG boiling range and press range
-90 to -1.1 degree c
170 - 17000kpa
safe havens
ground cover low lying areas buildings treed areas fire pumper or truck fog nozzle stream
BLEVE
boilind liquid expanding vapor explosion
warning signs potential BLEVE
Pressure relief device is working
Pitch or sound gets louder
Pinging, popping, or snapping sounds are heard
Visible steam from tank upon cooling – 100 C
Discoloration of shell at impingement
A buldge or bubble indicates serious localized heating of vapor area
naturagl gas concentratino
5-15 percent
ignition temp of propane
450 degrees c
generating and aplpying foam 3 steps
proportioning
foam generation
distribution
AR-FFFP
AFFF
alchohol resistant film forming fluoral protien
Aqueous film forming foam
.1
.1-.5
.5
1.0
deep seated fires in furniture, smouldering ground fires
wildland/grassfires
structural ff with fog nozzles or wild land foam nozzle
protecting structures exposursres, forming barres during wildland ff operations
1
3
6 percent
shallow hydrocarbon spills
severe hydro carbon and polar solvent fires
for hazmat vapor suppression
4 methods foam is proportioned
induction, injection, batch mixing, pre mixing
2 types of application systeams for foam
manual system - eductor and playpoipe
automatic system - build into new salisbury pump
max pressures when using eductor
The pump pressure at the eductor must be 1400 kPa to create the ‘venturi’ effect
The high pump pressure at the eductor (1400 kPa) creates a lesser pressure within the eductor which allows the foam to be pushed up (drawn into) the tube by the atmospheric pressure to mix with the water being discharged
From the eductor (whether located at the pump panel or at mid-length), the maximum length of 44mm hose that can be utilized is 60 meters , or four lengths
If more length (greater than four lengths after the eductor) is required to allow the playpipe to reach the area involved, then the lengthening will be added between the pump and the eductor
Make sure there is a firefighter to drop, and change, the eductor tube into the container when it is not at the pump
In order to reach the ‘at-the-eductor’ pressure of 1400 kPa, the pump operator must start with a pump pressure of 1400 kPa and increase the pump pressure depending on the number of 65mm hose lengths being used between the pump and the eductor (add 50 kPa for each 15 meter length of 65mm hose)
Final pump pressure in kPa = 50 (# of Lengths of 65mm hose) + 1400
The maximum pump pressure to be utilized for this purpose is 2100 kPa
It is advantageous to have the eductor and foam container at the pump as the pump operator can do both, and don’t have to carry containers to the location of the eductor
foam application techniques
roll on
bank down
rain down
