Tactical Edge Tuesday #7
- Fire Dept
- Mar 17
- 5 min read
BLEVE EMERGENCIES
If you have been practicing the craft for some time, the chance that you have encountered some sort of gas emergency is very high, and I am certain that almost every firefighter has either seen or will see a propane tank fire at some point, but they really aren't as common as the other calls we respond to. However, I do hope that you don't look at all propane fires, or gas leaks as routine, as a matter of fact, I hope you treat every call as a serious call until you determine otherwise. Bleve's have continued to injur and kill firefighters across our country, and many times its at an otherwise "ordinary" structure, vehicle, or outside fire.
If you're a new firefighter (and I say that with the upmost respect because I know how hard that is and I commend you for taking the steps you are right now), you may be asking yourself what a BLEVE is. I left if out of the title on purpose.
BLEVE stands for Boiling Liquids Expanding Vapor Explosion.
I couldn't find any nice work art or illustrations for you, so forgive the bland font.
A BLEVE occurs when pressurized containers heat to a a point that the vessel fails. The liquid inside begins to boil, the pressure of the tank increases and weakens the tank shell. Then the tank catastrophically fails, releasing superheated liquid that expands at a crazy rate. The best way I have found to illustrate the expansion ratio to fellow firefighters learning the rate of propane expansion is like this: One Gallon of liquid immediately turns into 270 gallons of vapor. So, One gallon jug is now occupying 270 gallon jugs of space at once. That expansion is what causes fireballs, shockwaves and shrapnel to travel extreme distances very quickly.
The primary killer at these types of incidents are most often not the flames, but the explosion and projectiles. NIOSH reports have indicated that firefighters 100+ feet away have been killed due to fragments flying from one of these events, and that fragments have been found almost a half a mile away from the incident locations.
I hope you're still with me, because one of the most important parts of this to understand is that when a propane tank has fire impingement, the tank can fail in as little as 10-20 minutes. So, yes, time matters here. We know Time as our enemy, and Speed as our weapon. But remember, these emergencies are not those you rush to without a proper understanding of it or without the proper PPE.
A few facts about LP Gas:
It is HEAVIER THAN AIR - IT LIKES TO HUG THE GROUND
It is colorless
It is odorless
It is non-toxic
Its Chemically Stable
It has no taste, but I don't recommend trying it
It has a low boiling point at -44 degrees F
It can travel a long distance before it finds an ignition source
It can create an explosive atmosphere without full saturation - so partial room involvement means danger if the gas is in a closed area.
It's ignition can cause a pressure wave and temperatures exceed 1800 degrees F
We find LP gas at the most:
Our homes for generators, water heaters, heating and cooking (Tanks ranging from 120 gallons - 500 gallons with 250 being a common size), and other applications
In vehicles as a fuel, or during transport to a Georgia Bulldogs tailgate (20 lb. cylinders)
On railcars
Storage Facilities (where they aren't required to add odor)
Many industrial sites.
WARNING SIGNS TO BE FAMILIAR WITH
Immediate Evacuation Triggers Include:
High pitched venting noises from relief valves
Visible discoloration or charring of the tank
Bulging or deformation of the tank shell
Flame impingment on the upper vapor space of the tank
Increasing flame intensity at the relief valve discharge
High Risk Fire Conditions Include:
Flame contact on the vapor space (top of the tank) - that is the most dangerous
Long duration exposure such as heavy fuel fires and structure involvement
Impingement on the tank that cannot be cooled quickly
BOTTOM LINE = IF YOU SEE, HEAR, OR FEEL THESE SIGNS
>GET OUT>
Another reason for a good quality size-up at a fire would include the officer in charge to identify pressure tanks early and establish safe zones when tanks are found close to fire. A quality 360 may save that rookie's you sent to the Charlie Side!!!!!
Remember that Distance=Survival at LP gas emergencies
So, ALWAYS do you best to operate from maximum distance whenever possible and use unmanned master streams and monitor nozzles when you are able to for tank protection.
Avoid positioning apparatus downwind and downslope. And if there are civilians downwind or downslope, change that!!
If conditions allow you should apply large volumes of water to the tank shell and focus on cooling the vapor space. NFPA states you need 500 GPM for minimum cooling, so someone must be thinking about water supply early on at these incidents.
ONE OF THE BIGGEST MINDSET SHIFTS IN THE MODERN FIRE SERVICE INCLUDES LETTING THE GAS BURN AND NOT EXTINGUISHING THE FLAME, BUT THE BEST PRACTICE IS TO SHUT OFF THE VALVE IF IT IS ACCESSIBLE AND SAFE. IF NOT YOU BEST PROTECT EXPOSURES.
COMMON FIREGROUND MISTAKES
Tunnel Vision on the Fire
Firefighters focusing on the structure fire and vehicle fire but miss the propane cylinders nearby or the fuel-fed hazard escalation FIX THIS BY ASSIGNING A SAFETY OFFICER WHO IS DIALED IN ON IDENTIFYING THESE HAZARDS EARLY FOR YOU
Getting Too Close
"It's just a grill tank" mindset
Advancing Lines inside projectile zones (rounded ends of the tank are high risk areas)
-THE REALITY IS EVEN SMALL CYLINDERS CAN ROCKET AND KILL!-
Misunderstanding Relief Valves
Seeing it vent and thinking to yourself "Oh, Its working properly."
The truth is that the relief valve activating is a warning sign, not a safety sign
Improper Positioning
Operating at the ends of the tank
Parking apparatus nearby
-THE REALITY IS EXPLOSION DIRECTION IS UNPREDICTABLE!-
ALWAYS, ALWAYS, ALWAYS, Watch for vapor cloud ignition and secondary explosions
Remember:
Distance is your best PPE so to speak
Propane Expands at a ratio of 270:1
Relief Valve Noise = Evacuation Trigger
Vapor Space impingement is the highest danger
If you can't control the gas, let it burn
Never trust tank direction in a BLEVE potential
Slow down mentally, even when the fire is moving fast, because the calm brings the speed.
Train on recognizing the containers with the new guys and gals, read the smoke, the flame, and the tank conditions. DO NOT FORGET THE TANK CONDITIONS BECAUSE YOU DON'T GET A SECOND CHANCE TO FIX THE FIRST MISTAKE HERE.........
This post is not all you need to know about BLEVE and LP Gas Emergencies, but I hope it was a good introduction for some and refresher for others. Watch the video below and finish the learning. I hope to see you soon at a live fire training event near you!
STAY SAFE and BE ELITE!
Reminder: Log your training appropriately with our Training Form.
Use the description: BLEVE AND LP GAS EMERGENCIES
Step Up, Let's Be Elite!
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