Talk:Boiling liquid expanding vapor explosion

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Toronto. Aug 10 2008. A BLEVE?

—Preceding unsigned comment added by (talk) 07:26, 26 August 2008 (UTC)

"Pronounced Blevy" - does that rhyme with Bevy? Or is it Blee-vee?

It rhymes with 'bevy'.

Mechanism of the explosion?[edit]

I do not understand how, after initial rupture, boiling liquid manages to produce pressures HIGHER that the initial pressure in the intact container. This seems to be impossible. Boiling releases more gas. Pressure is rising, and this should be reducing the intensity of boiling. Because at original pressure there were no boiling at all. Moreover, boiling COOLS the liquid.

Something is wrong here. The most simple explanation might be that pressure is not in fact increased so much during BLEVE and it doesn't exceed the original pressure. Just the large amount of produced gas and its significant venting speed at the rupture make BLEVE violent, incorrectly hinting at "high pressure". Does anyone know better? (talk) 19:09, 25 September 2008 (UTC)

Question on the thermodynamics after initial rupture - for a non-flammable fluid (say, steam) how can the pressure *increase* over the pre-event vessel pressure.
Clearly before the event, the liquid and vapor were in equilibrium; unless heat is added, then there's no additional energy available and therefore the pressure can only fall (if the fluid is supercritical, such as for supercritical cryogenics) or stay constant (as for "conventional" fluids, like water or liquified CO2). So, how can the pressure inside the vessel _increase_?
Is there a cite that clears this up? —The preceding unsigned comment was added by (talk) 18:15, August 23, 2007 (UTC)
The system does not remain in equillibrium. An open bottle of soda is near equillibrium and atmospheric pressure. Shake the bottle and it departs further from equillibrium; the pressure increases.- Ac44ck (talk) 15:50, 11 October 2009 (UTC)

Simple question needs answering in the article: Does the pressure at any point exceed the original pressure, or not, and if so then why? Surely data on this must exist. E.g., is the problem that any agitation of the vessel (such as boiling causes) will temporarily raise the pressure uniformly (exactly like a soda bottle shaken until the lid blows off)? Or is it that the initial leak grows bigger due to accelerated local deterioration caused by the high velocity flow (probably even supersonic converging-diverging nozzle and cavitation effects) around its edges? In only one of those two cases might one expect to detonate a tank just by suddenly turning open a good-conditioned valve. Or is it just that when an old tank completely fails (at a given pressure), any additional vaporisable-liquid contributes a weightier explosion/wave-of-gas compared to if the same tank had contained only vapour to begin with (in which case, regardless of whether liquid was present, the tank still would have completely failed anyway)? Or is there some highly non-equilibrium dynamic process, where a wave of low-pressure from the leak triggers a pulse of extremely high pressure from the liquid, placing non-uniform force over the vessel walls (which in some places may rupture before the whole vessel has a moment to adopt to any uniform pressure temporarily even)? Cesiumfrog (talk) 04:01, 16 February 2010 (UTC)

First, I believe it is a myth that a closed bottle of soda can be "shaken until the lid blows off" unless the shaking added enough energy to create a temperature rise in the bottle.
As to the question about detonating a tank just by suddenly turning open a valve. It probably depends on the size of the valve and how quickly it is opened. Other issues may become problems before the tank explodes:
Always open oxygen cylinders very slowly. Opening them quickly is very dangerous and can cause the regulator to explode.
Not said, but I imagine that if the valve is large and open far enough, explosion of the regulator might be followed by explosion of the tank. -Ac44ck (talk) 17:39, 20 November 2010 (UTC)
Explosions of oxygen regulators are caused by the presence of organic material (grease, dirt) combusting. An air regulator may contain rubber or grease. Venting gas through a valve causes a drop in temperature which can in more extreme cases lead to brittle fracture of some component. Neither of these are specific to BLEVEs.Chemical Engineer (talk) 22:18, 20 November 2010 (UTC)
Are all explosions of oxygen regulators caused by the presence of organic material? Why does it matter how quickly the valve is opened if there is no other cause? - Ac44ck (talk) 20:23, 10 April 2011 (UTC)
Opening the valve quickly can cause local heating which can ignite. Common causes are (a) air regulator used instead of oxygen (b) brass oxygen regulator incompetently serviced with oil or grease. (c) faulty aluminium regulators. Nothing to do with BLEVEs.Chemical Engineer (talk) 10:34, 25 August 2011 (UTC)

Mechanism > Water Example[edit]

I'm not an authority, but the text says that transition of liquid water to steam causes a 22x expansion. I thought it was ~1700x (see article Steam). Mvsmith (talk) 15:09, 12 June 2017 (UTC)

Texas City, TX doesn't belong in this article[edit]

The disaster in Texas City in 1947 was caused by exploding ammonium nitrate so I don't think that it should be included in this article. See Texas City Disaster for more information.

wysiwyg 21:25, 19 January 2007 (UTC)

Someone "corrected" the date from 1978 to 1947, so yes, while the 1947 explosion was not a BLEVE, the one in 1978 was. I guess they get lots of explosions in Texas City. --Bob Mellish 08:00, 30 May 2007 (UTC)

Steam explosion not a BLEVE[edit]

These two statemetns contradict each other: "When the liquid is water, the explosion is usually called a steam explosion.", and "A BLEVE can occur in a vessel that stores a substance that is usually a gas at atmospheric pressure but is a liquid when pressurized (for example, liquefied petroleum gas)." In my experience, the term BLEVE is restricted to the latter sentance. Fireproeng 07:09, 8 November 2007 (UTC)

This is sourced from a "how to" blog site for plumbers. I believe it is wrong and that it only applies to flammable materials. Citations are available to this effect. I too suggest deletion. --Old Moonraker (talk) 07:08, 11 October 2009 (UTC)
How does the flammability of the material enter into the mechanics of an expanding vapor explosion that is driven by a boiling liquid? If the flame front was within the vessel and had oxygen available to it, that would seem to be a deflagration. Such an explosion is due to burning vapor, without regard for the presence of liquid. This page talks about a water-based BLEVE:
Although normally associated with accidents involving flammable liquids like propane, a BLEVE can occur in a pressurized hot water tank in which only hot water and steam are released. A BLEVE occurs when superheated water (at elevated temperature and pressure compared to atmospheric conditions) is released through what may start as a relatively small fracture in the vessel.
The characterization of the source in the article as a "'how to' blog site for plumbers" may be read as disparaging. It contains information that explains why building codes contain certain requirements: they embody good judgement which was obtained by bad experience. -Ac44ck (talk) 15:13, 11 October 2009 (UTC)

Apparently also known as Blast Leveling Everything Very Efficiently. --Kizor 15:10, 4 February 2008 (UTC)

I've added an external link about propane BLEVE's. They are the most common pressure vessel ruptures we hear about and I felt some facts instead of videos might be appropriate. Mtt124 (talk) 03:47, 28 February 2008 (UTC)

Information is incorrect[edit]

Information in this article is incorrect. Please note that Bleve can happen with any liquid in a container. Because the container or vessel is holding water, as compared to LPG or Propane, it can still BLEVE. Tanks used in the industry are now required to have pressure relief valves that will open from excess pressure.

A BLEVE can occur when a vessel containing a liquid explodes or ruptures from being exposed to heat. Such explosions can be extremely hazardous. A vessel holding a liquid will build pressure as it is heated and the liquid expands. The liquid will expand exerting force to the container. Unless this pressure is released or heat is removed, an explosion can occur. A vessel that is already venting, can BLEVE if the pressure is not reducing from this venting action. A tell tail to this is the increase of pitch to the venting noise. Also a vessel can BLEVE quicker if the heat weakens the container to the point of failure. (talk) 14:52, 24 June 2008 (UTC) —Preceding unsigned comment added by (talk) 02:05, 10 June 2008 (UTC)

Fire in new image[edit]

The new image looks good, but it may give undue weight to the presence of an external fire.

How does the rate of heat transfer to the liquid from the external fire compare with the rate at which internal energy is released from liquid in the tank?

Perhaps an external fire may create an overpressure to cause the initial rupture, and it may make the situation worse by igniting the escaping vapor. A gas explosion may be a secondary effect of a BLEVE.

If an LPG tank falls over and ruptures, couldn't a BLEVE happen even in the absence of an external fire? - Ac44ck (talk) 03:14, 26 January 2009 (UTC)

Water heater[edit]

A water heater with hot water is a pressurized container. When the pressure is dropped do to a leak that can cause the water to boil. water boils at different temperatures depending on pressure.

Apollo 13[edit]

Was the LOX explosion of the Apollo 13 Service Module an example of this. Was this mechanism involved in that incident?

Basesurge (talk) 09:27, 1 December 2009 (UTC)

Blast leveling everything very effectively...[edit]

Lets gets some talk on this one. Why is this not a valid thing to include in an article on the subject? This is a nearly-universal backronym; i got to this page a long time ago by way of it. Wikipedia is not a paper encyclopedia, it doesn't need to be shipped or stored or flipped through endlessly searching for the right word... Sniper1rfa (talk) 23:23, 13 May 2010 (UTC)

It needs a citation. Some sort of Cite that would prove firefighters use this as a a backronym. BTW, I don't believe counts on this one. Exit2DOS CtrlAltDel 12:07, 14 May 2010 (UTC)
the phrase "blast levels everything very effectively" shows up as being indexed by google in feb 2001, 3 years before this article was created. That good enough? The phrase had to come from somewhere... —Preceding unsigned comment added by (talk) 04:36, 21 November 2010 (UTC) I've added it back in, I see no reason why it should be left out. The article is not exactly unwieldy due to its length...

Compressed gas not required[edit]

The reason I reverted the edits of Chemical Engineer is that the wording, "Gases such as propane may be stored in a more compact form by compressing them into a liquid ...." implies that BELVEs are confined to compressed gases, which is incorrect. Please discuss before reverting again with no explanation.Kilmer-san (talk) 16:07, 25 October 2010 (UTC)

But you have stated:
"If a vessel partly filled with liquid with vapour above filling the remainder of the container, is ruptured — for example, due to corrosion, or failure under pressure — the vapour portion may rapidly leak, lowering the pressure inside the container." You have omitted the critical fact that the pressure inside has to be higher than the outside, which is why I reverted. As this is an encyclopedia I include some explanation as to how the situation may arise to allow a BLEVE. I quote Kletz "A BLEVE occurs when vessel containing liquid under pressure, above its normal boiling point, bursts, releasing the contents with explosive violence."Chemical Engineer (talk) 23:14, 25 October 2010 (UTC)


This whole article needs a rewrite because it does not properly define BLEVE and "the mechanism" described here IS INCORRECT. Any closed container with both liquid and its vapor inside is pressurized, due to the vapor pressure of the substance itself. Adding heat to the container (and its contents) increases that pressure. If the container ruptures, THE PRESSURE INSIDE DROPS. Boiling of the liquid may result from the drop in pressure, but boiling WILL NOT INCREASE the pressure inside the vessel because it's open to the atmosphere. If the rupture does not allow the gases to escape quickly enough, BOILING is inhibited because the pressure still prevents molecules escaping the liquid. A BLEVE results ONLY if the vapor escaping the rupture ignites. It is this rapid oxidation that causes the "explosion" part of BLEVE. Rapid expansion of gas due to combustion blows the container apart, not the boiling of the liquid. Water and other non-flammable liquids can cause steam explosions, but they CANNOT INSTIGATE A BLEVE. Boyle's law of ideal gases describes the physics. Nickrz (talk) 21:30, 15 April 2011 (UTC)

  1. Cite?
  2. "Open to the atmosphere" does not mean the pressure can't increase behind an opening in the vessel. Else how could it ever explode in your scenario? - Ac44ck (talk) 03:30, 16 April 2011 (UTC)
1. Boyle's Law of Ideal Gases. Any elementary physics or chemistry textbook. If the pressure inside the vessel is above the vapor pressure of the liquid (for that temperature), the liquid cannot boil. If the container is vented to the atmosphere, boiling can only produce vapor at a pressure LOWER than the vapor pressure for that liquid at that temperature.
2. The vapor ignites both outside and inside the container. If the vapor is nonflammable = no explosion = no BLEVE. Nickrz (talk) 20:50, 21 April 2011 (UTC)
  • Which elementary physics or chemistry textbook discusses the transients involved in a BLEVE? Boyle's Law is for systems in equilibrium. A BLEVE far from equilibrium.
  • Flammable vapor inside the container needs oxygen to burn. How does oxygen get into a pressurized tank of propane to make a BLEVE?
You have given no cite. Your assertion is unverified. - Ac44ck (talk) 05:23, 22 April 2011 (UTC)

Thermodynamically, boiling is endothermic. So whatever energy was available in the liquid, less energy is available in the corresponding vapor, since some has gone into the state transition. This makes it difficult for me to understand the (uncited) "leak -> lower pressure -> boiling -> overpressure" causation chain. Combustion, by contrast, is exothermic: for example, the reaction of a rapidly expanding cloud of propane vapor with air, in a fuel-air explosion. Olawlor (talk) 10:15, 25 August 2011 (UTC)

There's a BLEVE simulator used by firefighters here [1], and it shows the blast hazard distances due to the energy stored in the vapor, liquid, and combustion of propane, which increase in that order. There is also a technical paper here [2] which agrees with the article's assertion that depressurizing a superheated liquid may "sometimes even surpass the initial pressure," which surprised me! One possible explanation is that the potential energy in the superheated liquid is transformed to kinetic energy in the form of gas pressure.

Olawlor (talk) 10:41, 25 August 2011 (UTC)


Re-wrote this section for clarity. The original wording did not usefully explain the details of a BLEVE.

Things to note:

A BLEVE can occur without combustion. As somebody stated, if there is no oxygen or oxidizer there can be no combustion, however a BLEVE can without question still occur.

With regards to the "high pressure", there can be very high pressures at the front of the shockwave. These pressures would in fact cause some portion of the substance to re-condense into a liquid. It is very common for shockwaves from all explosions to be readily visible by the condensation occurring within the shockwave.

A bleve with a flammable substance can be ignited by extreme heating from friction as the substance rapidly passes some obstruction such as the torn remains of the vessel which once contained it.

— Preceding unsigned comment added by Sniper1rfa (talkcontribs) 00:25, 19 June 2012 (UTC) 

Basic physics is not explained and "misunderstood" in the article as it stands[edit]

Key points:

(1) Thermodynamically, when the overpressure preventing a superheated liquid from boiling is released (down to say atmospheric), in general only a portion of the liquid can flash to gas if the system is isolated from further heat input. Simply put, the latent heat of evaporation must be derived from the energy that was used to superheat the liquid. For water, about 2kJ/g is required to convert liquid to steam, whereas superheating water from 100 to 200 degrees C provides only about 400J/g. Thus only about 20% of the superheated liquid can flash to steam in this case. The example in the article where it says "It is obvious, then, that 204.4°C (400°F) liquid water at atmospheric pressure must immediately flash to gas causing an explosion." is nonsense. This misconception is also present in the accompanying diagram, which shows the entire contents of a ruptured container converting to gas.

(2) Secondly, when the overpressure preventing a superheated liquid from boiling is released, the possible fraction of liquid that can thermodynamically convert to gas will not necessarily do so "explosively". For modest superheat, the liquid will probably just boil vigorously at nucleation sites on the container surface. Rapid conversion to gas throughout the liquid volume ("homogeneous nucleation") can be ensured by exceeding the "superheat limit temperature".

See e.g., for a detailed discussion of the physics of BLEVEs (talk) 18:34, 25 March 2013 (UTC) Douglas Liddell

Please rewrite with additional details. I originally rewrote the whole article because it was completely incorrect. The current article lacks detail but has the correct skeleton for expansion. I left all discussion of latent heat and so-on out, similar to the way a basic description of a nuclear explosion would leave out the details of exactly how much fuel is consumed prior to the core being blown apart and becoming sub-critical. — Preceding unsigned comment added by (talk) 17:07, 15 September 2014 (UTC)


The article is written in poor tone. The text comes across as both antagonistic and overly instructive.

"There are three characteristics of liquids which are relevant to the discussion of a BLEVE" - please rewrite in a friendlier more accessible way. This is not a "discussion", this is an encyclopedic article. Focus on the facts, and boil it down for the reader.

Italicized words ("liquid"): Get rid of this. It comes across as confrontional: "if it doesn't involve liquids it ain't a bleve". Rephrase in a neutral tone - or even remove altogether; the "L" of bleve is after all "L for liquid".

"Imagine, for example". Inappropriate tone. Too repetitive. Talking down to the reader.

"It is important to note that a BLEVE need not be a chemical explosion" - why is this important? Is it because the authors are fighting an edit war or because there is a real reason? (talk) 16:34, 10 July 2013 (UTC)

Also the image caption: "Note that BLEVEs do not necessarily involve fire." Ok, I'm noting it. Wait, why am I taking notes when reading Wikipedia? And why is the image showing a big prominent fire, again? (talk) 16:38, 10 July 2013 (UTC)

Rather than talk about it, rewrite in a more appropriate tone. The italicized words are for clarity, because the previous incarnation of this article was extremely confusing in that regard. It's very important to be clear that a BLEVE is caused by the bulk transition from liquid to gas.

The differentiation between a BLEVE and a chemical explosion is important because everybody always imagines a fiery propane explosion, which is misleading and prevents the reader from understanding that a BLEVE can occur even with chemically inert substances. — Preceding unsigned comment added by (talk) 17:11, 15 September 2014 (UTC)

Liquor Aging Warehouses[edit]

The external reference HID - SAFETY REPORT ASSESSMENT GUIDE: Whisky Maturation Warehouses, mentions BLEVE 8 times. Here is another reference to a BLEVE event at a whiskey aging (maturation) warehouse:

Also, there is an article that says, “thousands of bourbon casks had been exploding like gunfire at the peak of the blaze in a seven-storey warehouse”. It is at: — Preceding unsigned comment added by Final Approach (talkcontribs) 10:40, 3 April 2014 (UTC)


I have added the logo for the Chemical and Biochemical Engineering Project, since chemical engineers must often consider the potential hazards of BLEVEs in designing process facilities. Many of these engineers have knowledge and experience that can add to this topic. Less-experienced engineers may consult Wikipedia for guidance on the topic. ChemE50 (talk) 05:33, 10 September 2014 (UTC)

Crude oil and diesel don't BLEVE[edit]

I've removed the reference to the incident involving the oil tanker train that wrecked in Canada. I'm no rocket surgeon but I'm pretty sure crude oil does not boil at room temperature and therefore does not belong in a BLEVE article.

Strange Italica in paragraph before Water Example[edit]

This paragraph:

If the pressurized vessel, containing liquid at high temperature (which may be room temperature, depending on the substance) ruptures, the pressure which prevents the liquid from boiling is lost. If the rupture is catastrophic, where the vessel is immediately incapable of holding any pressure at all, then there suddenly exists a large mass of liquid which is at very high temperature and very low pressure. This causes the entire volume of liquid to instantaneously boil, which in turn causes an extremely rapid expansion. Depending on temperatures, pressures and the substance involved, that expansion may be so rapid that it can be classified as an explosion, fully capable of inflicting severe damage on its surroundings.

Is full of italics that really break the 'flow' as you read. They aren't really serving a purpose, it's as if the writer decided you weren't capable of adding appropriate emphasis and did it for you. I will remove the italics it a few days if no one replies. WikiWisePowder (talk) 04:46, 18 December 2015 (UTC)

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