Monthly Archives: April 2007

BLEVE- Boiling Liquid Expanding Vapor Explosion

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There is kind of fire behaviour called a BLEVE– Boiling Liquid Expanding Vapor Explosion.  A BLEVE is what happens, for instance, when a closed container of flammable liquid is exposed to strong heating.  It can be caused by an external source, like a pool of burning liquid around the container, or it can result from a runaway reaction within a drum, cylinder, or tank.  The internal pressure builds up more rapidly than it can be vented and the containment fails, often explosively. It is interesting to note from the above link that boiling action of the liquid phase in the container absorbs energy and has a cooling effect, but there may come a point where the vapor pressure rise above the liquid exceeds the capacity of the relief discharge capacity and the vessel fails, discharging liquid and vapor across the burn zone.  At minimum, discharge and ignition will lead to a large flare, or if conditions are right, an actual detonation of the fuel/air mix could happen over a relatively large space.

These things often begin with some kind of tank or tanker accident (link updated 6/10/16) resulting in a discharge and ignition of flammable liquid.  As responders arrive they find a burning pool under or next to the tank(er).  Naturally, firemen and bystanders try to help those who may be hurt. As the minutes tick away and the fire becomes more aggressive and the tank gets hotter, the firefighters get their equipment in place and attempt to cool the tanker and suppress the fire.  Suddenly the tank fails and there is a prompt bulk discharge of liquid and vapor yielding a large fireball which may include an explosive shock, flying metal debris and a dangerous heat pulse.  It is at this point that the surviving bystanders and responders see the error of their ways.

Containers of flammable liquids rarely explode in a symmetric fashion so the container or its fragments are likely to be sent flying at high velocity, possibly spewing flammable material as it moves.  Even a relatively small volume of flammable liquid dispersed explosively can fill a large surrounding space with a fireball.

All chemical plants have their protocols for emergency response.  It is important for those in charge to recognize an incipient BLEVE and respond accordingly.  But even academic chemists should familiarize themselves with the phenomenon.  A fire in the lab engulfing closed containers of flammable solvents is extremely dangerous and very quickly firefighting may become your last earthly act, especially without personal protective equipment.  It is easy to under estimate the violence of these things.

Every lab person needs to look inward and decide what their personal limit is for dropping the fire extinguisher and running for the exit.  In my sophomore organic labs, the seed I planted in the students mind was this: The main purpose of a fire extinguisher was to fight your way to an exit.

Sacred Cows Make the Best Hamburgers

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I suppose I have lost more frequently than I have won in my lifelong avocation of taking on sacred cows in the battle of wits.  But, truly, sacred cows make the very best hamburgers.  Pass the A1 …

Some new blogs have been given a place of honor in the blogroll.  Good writing and laser sharp insight are the keys to this ascendency. If the dear reader is conservative and prone to weeping or bed wetting, it is probably best to click along at this point.  

There is a hilarious post over at Lawyers, Guns, and Money called Birthday Girl.  Side note: A lawyer friend is fond of saying “Lawyers, guns, and money- pick any two”.  

And then, what can I say about Jesus’ General?  Read General JC’s letter to the Secret Service re Cheryl Crow.  If you are keen on some serious in-your-face-atheism, check out Hellbound Allee. Then there is one of the best Christian evangelical lampoons ever, Landover Baptist. 

The Huffington Post is a recent find and is a treasure trove of political blogging at its finest- well, if you are a liberal.  Read the open letter to Rudy Giuliani by my fellow Coloradoan, Gary Hart. 

Then there is the Proceedings of the Athanasius Kircher Society.  The post on the Do-Nothing Machine is particularly amusing.  The reader may recall Th’ Gaussing’s previous post on the Katzenklavier. 

Finally, The Agonist has some interesting insights into politics and is well written. I also like Goosing the Antithesis for its skeptical stand against belief in the supernatural.

“Riding Rockets”- A Review

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I just finished reading Mike Mullane’s autobiographic “Riding Rockets“.  Mullane is a retired mission specialist astronaut with 3 missions under his belt.  It turns out that Mullane and I share one discouraging life experience.  I also wanted to be an astronaut and was also disappointed to learn in college (Air Force ROTC) that my nearsightedness would prevent me from getting a pilot slot in the Air Force or Navy.  Undaunted, Mullane went on to the next best option of GIB (Guy In Back) and became a USAF weapon systems officer.  His transition to astronaut from GIB was made possible by the NASA’s decision to eliminate the requirement of pilot experience as a prerequisite for mission specialist .  No doubt his degree from West Point, 150 combat missions in Viet Nam, test pilot school at Edwards, and a masters in aeronautical engineering helped him a bit.  I realized that I was a nearsighted, pathological smartass and left ROTC and went into chemistry.  Mullane persisted and got into space. I succumbed to the enchantment of organic chemistry and explored conformational space.

Mullane writes rather well and provides a reasonably balanced narrative over the time spanning his career. I would say that the main reason to read the book would be to get some insight into life in the astronaut corps.   If you put two people in a room, you have politics.  And it is no different with astronauts. Mullane details what can only be described as a byzantine system of decision-making for mission assignments and the characters who made these decisions.

Mullane describes in considerable detail the experience of a scrubbed launch. He bid farewell to his family and strapped a fully fueled shuttle to his backside 9 times for 3 launches.  Mullane tells of his own private fears and the fear that was (is) felt among many other astronauts- a feeling quite apart from the confident and laconic persona they might show in public. Indeed, he has been outspoken in regard to the safety of the shuttle fleet and in a manner uncharacteristic of astronauts, generally.

Far from being a monolithic group of superheros, the astronaut corp consists of a surprisingly diverse group of individuals.  As a group, astronauts are super achievers and not lacking the usual spectrum of attributes you might expect.  There is no shortage of ego or swaggering bravado.   Historically, astronauts come from an aeronautical background and as such, are accustomed to the flight environment and the norms that go along with it. During Mullanes tenure at NASA, the program saw civilian and other non-traditional astronauts take increasingly important roles in the mission.  In particular, this period of time following the first trial flights saw female astronauts accumulating a considerable number flight hours on orbit.

He describes in detail how the astronauts felt after the loss of Challenger and Columbia.  Mullane is of the opinion that the shuttle should have a better crew escape system.  Evidently he logged an ejection from an F-111, so he has first hand experience with bailout systems. There are literally thousands of parts and systems whose failure could tragically end a mission and the lives of its crew.  But like everyone who wants to fly in space, you swallow your fears and strap in anyway.

In the context of books in this genre, I’d give him a A- for his courage to be critical of NASA.  He now works as a motivational speaker.

Mixing and Unmixing

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Today was take-your-kid-to-work-day.  In honor of this we put on a chemistry show in one of the labs.  Burned some Mg ribbon, shrunk some balloons in LN2, blew up some balloons with dry ice, reduced iodine with ascorbic acid, and we unmixed some NaCl and carbon black. 

One of the barriers to teaching chemistry is a level of physical abstraction that is hard to get around.  It is hard to get around trivial explanations when the audience is not ready to discuss electrons.  Many of the really insightful concepts in chemistry are inherently abstract and age inappropriate for the younger crowd, so to compensate, chemistry demonstrations are often heavy in the whizbang components.  That’s fine.  It should be fun and visually appealing, especially for K-6. 

I like to do mixing and unmixing because it demonstrates something about materials handling.  It also represents an activity that occupies much of our time.  Separation science is not commonly called “unmixing”, but for chemistry demonstrations it causes kids to ponder the problem for a bit.  They all have experience in mixing things- we talk about that.  Then I ask the question “What if I asked you to unmix that KoolAid”?  A few of the more worldly ones might suggest boiling off the water.  But most kids seem to be stumped- they will admit that they would have never considered the possibility of unmixing. 

So we dissolve some NaCl in water and make a solution.  The use of a magnetic stirrer and stirbar makes way for a minor diversion with magnets and iron filings. Then we blend in a bit of carbon black. Using a Buchner Filter, filter paper, and Celite, we do the vacuum filtration, showing the remains of the carbon in the Celite.  The filtrate is then treated with some “Anti-Solvent” like acetone and the salt comes crashing out. 

Yeah, I know. It is pretty tame.  But it can be done cheaply in 45 minutes and the kids can see their parents actually doing something. 

Jane Goodall

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Went to a public lecture by Jane Goodall last night. The arena was packed.  She and members of her institute have found a type of formula for combining conservation and economic growth.  At some point she realized that you can’t sell conservation in a vacuum.  People who live near fragile preserves like Gombe have to make a living.  They need food and firewood. 

Human population pressures also threaten the shrinking wildlife preserves all over the world and in Africa in particular. One way to encourage lower population growth is to look after public health and, in particular, the welfare of women. They’ve noticed that families naturally tend to have fewer babies when infant mortality rates lower. Lower mortality rates can be achieved through the application of very fundamental improvements in hygiene and health care.

One of the critical approaches they are taking in Africa is to improve the life of women through micro loans.  This has proven effective in many other parts of the world and Goodall reports it is having a beneficial effect in Africa as well.

As I sat and listened to the lecture, I was overcome with the futility of our ever increasing consumerism.  Take our collective response to the increasing scarcity of petroleum.   The big ideas seem to involve finding new ways to sustain high consumption- e.g., the replacement of petroleum with ethanol or hydrogen.  The idea that we might have to throttle back our per capita consumption of stuff extracted from the ground is ignored.

Well, of course the national stage isn’t filled with people promoting reduced consumption.  There is no money in reducing demand. Who wants to hear that? 

Minimally, the USA must go the way of Europe in terms of lower average consumption.  Higher population density combined with higher priced energy will lead to more modest consumption of goods due to lifestyles adjusting to scarcity. 

Intermission

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I’m up to my gills in really fascinating stuff at the day job, but none of it can be blogged.  Pity.  So I have to blog about silly links and make fun of POTUS.  I hope the reader will pardon this intermission.  Here is a platitude shamelessly lifted from Making Light–

“The whole point of society is to be less unforgiving than nature.”  

Amen, brother.

Bush II. Sphericated or Flaticular?

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Here along the front range of the Rocky Mountains we have a few alternative newspapers available- you know, the kind not owned by Rupert Murdoch. They tend to be a bit Bohemian and consequently are shunned by righteous Dittoheads. Other parts of the country have them as well- college towns mostly. They cater to those of us who aren’t afraid to be known as liberals.  These papers run a syndicated cartoon called This Modern World by a guy known as Tom Tomorrow. 

Because of copyright issues, I’ll have to link to the site rather than paste an image.   

Happy 100th Birthday Albert Hoffmann!!

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Albert Hoffmann, the discoverer of LSD, turned 100 years old this year on Juanary 11th.  Happy Birthday, Albert!  Scienceblogs.com relates the story of Hoffmann’s first deliberate LSD trip on April 19th, 1943.  You might recall that Hoffmann was the Sandoz chemist who stumbled upon the psychotropic activity of lysergic acid diethylamide.  

Just this last week, the medical journal The Lancet called for an end to the “demonization” of psychedelic drugs, according to Guardian Unlimited.  The motivation behind the editorial in the Lancet was to urge a loosening of taboo’s connected with the use of psychedelic compounds.  The widespread criminalization of psychedelics has made research with these interesting molecules quite problematic. 

Perhaps the day will come when such materials are decriminalized and it will be possible to visit a psychedelic spa where one could go to have a safe dosage administered by qualified staff.  But it wouldn’t be all fun and games, though.  While the euphoric experience can be prolonged and profoundly vivid, there is a dark side.  An account of the experience of the psychiatrist Werner Stoll is described in Chapter 4 of Hoffmanns book “LSD. My Problem Child”.

Hoffmann and Sandoz would watch their discovery move from a psychiatric adjunct to a full fledged inebriant adopted by a counter culture movement.  In his book, Hoffmann laments-

    This joy at having fathered LSD was tarnished after more than ten years of uninterrupted scientific research and medicinal use when LSD was swept up in the huge wave of an inebriant mania that began to spread over the Western world, above all the United States, at the end of the 1950s. It was strange how rapidly LSD adopted its new role as inebriant and, for a time, became the number-one inebriating drug, at least as far as publicity was concerned. The more its use as an inebriant was disseminated, bringing an upsurge in the number of untoward incidents caused by careless, medically unsupervised use, the more LSD became a problem child for me and for the Sandoz firm.

    It was obvious that a substance with such fantastic effects on mental perception and on the experience of the outer and inner world would also arouse interest outside medical science, but I had not expected that LSD, with its unfathomably uncanny, profound effects, so unlike the character of a recreational drug, would ever find worldwide use as an inebriant. I had expected curiosity and interest on the part of artists outside of medicine-performers, painters, and writers-but not among people in general. After the scientific publications around the turn of the century on mescaline-which, as already mentioned, evokes psychic effects quite like those of LSD-the use of this compound remained confined to medicine and to experiments within artistic and literary circles. I had expected the same fate for LSD. And indeed, the first non-medicinal self-experiments with LSD were carried out by writers, painters, musicians, and other intellectuals.

Today, psychedelic substances are considered to be drugs of abuse and their use will lead to a long stay at the Gray Bar Hotel. Our Puritanical heritage seems everlasting. But rather than wallow in pity for my unenlightened brothers and sisters, I look forward to a brighter future where one could sit in a licensed psychotropic suite and explore the deepest recesses of consciousness brought out in full non-linear display, say, while listening to music. Everybody associates acid rock with LSD. That’s too easy. I’ve often wondered what it’d be like to listen to Leon Redbone in an altered state of consciousness.  Kinda curious about what a baritone sax does to a brain on acid.  Or David Bowie- Major Tom.  I’m showing my age. 

Along Came ChemSpider

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There is a new resource out there called ChemSpider.  In the few searches I’ve had a chance to do, it seems to be pretty efficient at separating a lot of the wheat from the chaff that you’d get just using Google.  It would be interesting to hear what others think of it.  According to the informative FAQ page, ChemSpider is a highly specialized chemistry search engine.  And, did I mention it’s free?  Yeah baby.

To begin you enter a name, CASRN, tradename, synonym or SMILES. This generates a report of hits. Click on an ID number or a structure and another page brings up hotlinks to various resources on the web. Click on the Data Sources link and another page will come up with a variety of data sources and their unique external ID numbers. Click on the molecular formula link and it pops off a Google search of the formula.

Obviously, this isn’t the same as a SciFinder search- you don’t get access to journal downloads and article bibliographies.  It connects you to a variety of public access sites that appear to be data repositories and collections of commercial suppliers.  But it is a real improvement over a raw Google search.  You don’t get the rats nest of links to publishers (i.e., Wiley, Elsevier, etc), expired colloquium notices, or literature citations from curriculum vitae on faculty websites.  

It will convert names to structures and, using ACD/Labs software, generate calculated physical properties.  I would be hesitant to enter the identities of confidential materials just yet. I do not know if they compile entries into a database or not.  I’m not convinced that I would enter a sensitive confidential material on it until I had a chat with an attorney about the question of disclosure.

All in all, it seems to be a useful tool for web searches.  I have only scratched the surface of what this thing will do.  Give it a try and see what you think.

First Class Tickets to Stockholm

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The buzz has begun for the 2007 Nobel Prize in Chemistry.  Over at ChemBark a list of fields and potential awardees is presented.  Odds are offered.  It is interesting to ponder.  In case you were wondering, the identities of the awards committee for 2007 is actually published.

When the committee calls for my opinion, I’ll have to set ’em straight.  First I’ll scold a bit about the snub of some early workers in asymmetic synthesis and how they were overlooked in 2001. People like Henri Kagan for C2 symmetric ligands among other things and Kurt Mislow for basic contributions to stereochemistry.  The guys who won in 2001 were deserving, but the omission of Kagan and Mislow is a shame.

I would like to see some organometallikkers like Suzuki, Heck, and Sonogashira get the recognition for their contributions to coupling chemistry, but I’m not sure it is a Nobel Prize body work.  I would prefer to see Bergman , Whitesides , or Harry Gray get the trip to Sweden for their fundamental contributions to organometallic and bioinorganic mechanism work. 

There is my free advice to the commitee.