Hooo-boy! This is a topic that should have waited 'till Friday. BUT,
since it was started, we need to discuss this. Because as engineers, we
need to know whether or not this is some sort of urban myth, or does it
hold up to scientific scrutiny?
Before we move on to investigating whether or not some doctor blew-up
some poor bloke during an operation, I would like to present this United
States Patented device for your consideration:
http://tinyurl.com/2ugj9m
It's amazing what one can do when one has an abundance of time on their
hands, isn't it?
I did find the following story:
Dr. Michael Levitt, a Minneapolis gastroenterologist who is probably the
world's leading expert on flatulence, tells of a somewhat gassy patient
who was having a rectal polyp cauterized one day and unexpectedly
exploded on the operating table.
No fooling. An electric spark caused the hydrogen in the patient's
bowels to detonate, blasting the surgeon backwards against the wall and
slamming the patient's head into the table. The explosion also ripped a
six-inch hole in the patient's large intestine. Luckily, they were able
to sew him up OK and the poor guy recovered.
I also found the following article below about Dr. Michael Levitt who is
probably the leading expert in this field and explains everything you
ever wanted to know about intestinal emmisions...
What a Gas
by Jeffrey Kluger
There are worse places to be than Dr. Michael Levitt's waiting room.
Chernobyl, for instance. Or Love Canal.
It's not that there's anything wrong with Levitt's facilities
themselves, you understand. Indeed, as doctor's offices go, they're
better than most. There are no millennia-old copies of Travel & Leisure
on the coffee table (A Weekend in Pangaea!), no sour balls from the
mid-1950s in the receptionist's candy dish, no relentless Muzak
repetitions of The Girl From Ipanema. No, the problem with Dr. Levitt's
waiting room is Dr. Levitt's patients.
Michael Levitt is a gastroen-terologist working at the Veterans Affairs
Medical Center in Minneapolis. The term gastroenterology, of course,
refers to the branch of medicine that treats ailments of the stomach and
bowels and comes from the Greek gaster, for belly, and enterology, for
someone who really ought to wash his hands before making you a sandwich.
For a medical specialty high in heroism and low in glamour, you can't do
much better than gastroenterology, but in Levitt's practice the stakes
have been raised. For the past 15 years, Levitt has been roundly
recognized as one of the world's leading authorities on the science of
flatulence.
Flatulence is the means by which the body rids the colon of unwanted
gases, the intestines of unwanted pressure, and crowded theater rows of
unwanted strangers. Its familiarity notwithstanding, it has generally
ranked near the bottom of most people's lists of Impressive Things the
Body Can Do--just a notch above the ability to flatten Coors cans
against our foreheads. Despite the low esteem in which nature's joy
buzzer has been held, however, a handful of researchers have made it the
chief object of their study. What, they have asked themselves, can it
tell us about the functioning of the body? How, they have challenged one
another, can it be alleviated when it becomes excessive? Why, their
families have asked them, couldn't they at least have considered a nice
podiatry practice? Levitt is one of the rare scientists who have been
willing to tackle these questions, and after 19 years in the flatus
game, he does not regret his choice.
An enormous amount of lore has grown up around the phenomenon of
flatulence, he says, much of it untrue. Debunking these myths and
uncovering the truth is like investigating any poorly understood area of
medicine. The answers are all there--if you're willing to go after them.
Levitt came by his interest in eruptive science in a somewhat dramatic
way. In 1976 a patient approached him with what Levitt later decorously
described in a New England Journal of Medicine paper as a five- year
history of passing excessive flatus. The demure phrasing in Levitt's
writing did nothing to capture the problems his patient faced. Since
1971, the prudently unnamed 28-year-old male confessed, he had been
passing intestinal gas far more than he ever had before in his life, and
certainly more than any of his understandably put-upon friends and
family members. For the previous two years, he had been keeping a
scrupulous record of his personal greenhouse emissions, and when he
revealed these so-called flatugraphic recordings to Levitt, the doctor
was taken aback. On an average day the patient recorded 34 episodes of
flatulence, with some days cresting into the low 40s. Levitt did not
have any data on how this compared with the output of the ordinary
person, but even in a globally warmed, ozone-shredded,
chlorofluorocarboned world, this sounded bad. Before his unhappy patient
detonated at a mooring mast in Lakehurst, New Jersey, Levitt decided to
take his case.
In treating a man complaining of flatulence, there are many things a
doctor must consider--not the least being that the patient is a man.
From toddlerhood to dotage, there are few skills more highly prized by
the average male than a facility with flatulence. Why men should seem
more open about their gastric volatility than women is a mystery, but
from a sex whose inventiveness gave the world the noogie and the wedgie,
a fascination with all things intestinal should not come as a surprise.
While most men do what they can to curb this natural impulse, limiting
themselves to such flatus surrogates as whoopee cushions and fireworks,
an affinity for flatulence remains.
To study a problem of extraordinary flatus, Levitt needed data on what
ordinary flatus is. Recruiting seven highly cooperative volunteers, he
requested that they spend at least a week keeping flatugraphic logs of
their own, recording how frequently they stirred intestinally and when
these events occurred. While taking the time to note such events would
not make for an especially social week, it would make for a
scientifically enlightening one, providing Levitt with what was almost
certainly science's first flatulence control group. When the results
were in, it was clear that control was just what his seven volunteers
did have and what his troubled patient didn't.
In the group I chose, Levitt says, the mean flatus frequency turned out
to be 13.6 episodes per day, with no statistically significant
differences attributable to age, gender, or other discernible variables.
The upper limit for even the most gaseous of these subjects was less
than 20. In all cases the daily output was considerably lower than my
patient's 34, indicating that his problem was quite real.
More disturbing than the frequency of flatus from the afflicted man was
the quantity of effluence produced by each event. It's well known that a
flatulent episode can range from a barely detectable rumble to a
propulsive burst sufficient to attain low Earth orbit, depending on
general health and recent visits to all-you-can-eat salad bars. With the
help of internally worn rectal tubes and 100-milliliter collection
syringes, an earlier study had determined just what the standard output
of all these eruptions is.
The average person appears to release between 500 and 2,000 milliliters
of gas per day rectally, Levitt says, with the average volume of what
passes at once varying between 35 and 90 milliliters. The young man I
was treating released an average of 5,520 milliliters per day, or 162
milliliters per event.
By any measure, it was clear that Levitt had discovered the Joltin' Joe
of digestive distress, but before consigning the unfortunate man to a
private wing in gastroenterology's Hall of Fame, Levitt knew he'd have
to investigate further. The next step, he decided, was to study not just
the quantity of the patient's gaseous output but its makeup. Given the
power of intestinal exhaust to turn heads, clear rooms, and in extreme
cases fell whole swaths of old-growth forest in the Pacific Northwest,
this least fragrant vapor would seem to be made of only the most pungent
stuff. Yet according to analyses Levitt--and later others--conducted on
captured flatulence, intestinal gas can be surprisingly benign.
When you analyze rectal gas, Levitt says, you find that it is about 99
percent carbon dioxide, hydrogen, nitrogen, oxygen, and methane. Most of
these gases are either swallowed inadvertently when food is eaten or
released from the food as it is digested. What makes this remarkable to
most people is not just that these gases are so common but that they are
also utterly odorless.
For flatus to attain its singular bouquet, it must rely on the remaining
1 percent of the gas that makes it up--a percent composed of very
different stuff, which comes from a very different source. Like all
complex organisms, the human body is home to millions of microorganisms
that live in our hair, pores, and even our internal organs. The part of
the body that is apparently zoned for the most residential
development--at least by house-hunting one-celled organisms without much
of an eye for resale values--is the digestive tract. Among the better
known microbes that receive their E-mail and E! channel in your
intestines is the prolific E. coli. Among the lesser known are
Klebsiella and Clostridium. All these organisms live for the most part
in the colon, where they attack and consume undigested food and in turn
generate their own waste products. In the case of microorganisms, waste
usually means gas, and in the case of these microorganisms, that gas can
be pretty ripe stuff--usually molecules containing sulfur, such as
dimethyl sulfide and methanethiol. When these waste products build up to
a sufficient level, they are released with the rest of the gas in the
bowels, announcing their presence--and too often yours--to the world.
The odoriferous gases present in flatus are present in extremely small
concentrations, Levitt says. It is a testament both to the pungency of
the gases and to the sensitivity of the nose that we can detect them so
readily.
Of course, not all episodes of flatulence carry an olfactory price tag.
Some people, it seems, can release all the intestinal gas they want with
no one the wiser, while other people seem to be unable to enter a room
without first having to file an environmental impact statement. While
it's tempting to conclude that individual quirks of individual
metabolisms account for these differences, the answer usually has less
to do with our bodies than with what we put into them--particularly when
what we put into them are carbohydrates.
Nutritionists have long known that while there are many kinds of
carbohydrates present in food, Levitt says, not all of them are
digestible. Generally it is only the simplest carbohydrates, made up of
the simplest sugars, that we're able to process. Some complex
carbohydrates-- those made up of three or four sugar molecules--can't be
broken down by normal metabolism. When these get into the digestive
tract, they are simply passed along to the colon, where the intestinal
flora get hold of them.
Among the foods with the fewest complex carbohydrates and thus the
fewest flatulent consequences are meat, fish, grapes, berries, potato
chips, nuts, and eggs--the so-called normoflatugenic foods. Further up
the gaseousness scale are pastries, potatoes, citrus fruits, apples, and
breads, all of which contain some complex sugars, and thus some
potential for flatulent fallout. At the top of the explosiveness list
are the Fat Man and Little Boy of our diets--those foods that are
practically nothing but complex sugars. Among these most eruptive
edibles are beans, carrots, raisins, bananas, onions, milk, and milk
products.
When Levitt began treating his grievously gassy patient, it was these
well-nigh radioactive consumables that first drew his attention. In his
initial journal paper, as well as in a subsequent paper entitled
Follow-up of a Flatulent Patient (itself later followed up by Flatulent
Patient: The Musical!), Levitt described the painstaking process by
which the patient altered his diet to determine which foods were
responsible for his distress. During the first three weeks of the
patient's treatment regimen, Levitt restricted him to the
normoflatugenic foods and got immediate results: the incidence of flatus
fell from 34 bursts per day to fewer than 17--well within the normal
range. After this trial period, Levitt and his patient tested the
possibility that the young man's gas- producing proclivity had
diminished by adding a full quart of milk to his diet.
While residents of Minneapolis do not refer to The Day Michael Levitt
Gave His Flatulent Patient Milk with the same post-traumatic numbness
exhibited by, say, survivors of Mount Pinatubo, the event could not have
gone wholly unnoticed. In the 24 hours that followed the milk ingestion,
the patient reached something close to critical gaseous mass, recording
fully 90 episodes of flatus in his flatugraphic diary, including one
especially productive three-hour period in which he experienced nearly
60 intestinal utterances. The cause and effect between input and output
was so immediate and so direct that Levitt knew he had found his
smoking, uh, gun.
It turned out, he says, that this patient was lactose intolerant.
Lacking the enzyme to digest the carbohydrates in milk, he simply passed
them on to his colon, where the bacteria digested them for him. In many
lactose-intolerant patients, milk ingestion can lead to gas. In this
patient the intolerance was severe, so the gas problem was, too.
The solution to the patient's gaseousness was simple, involving nothing
more than maintaining the low-flatulence diet, and on those occasions
when milk was ingested, consuming it only with an accompanying dose of
lactase, an enzyme that aids in milk metabolism. In the years since,
Levitt has lost contact with the now middle-aged man, and with the
exception of a few false alarms--California's 1994 Northridge quake, for
example--all has been quiet on at least that flatulence front. But even
though his patient's mystery has been solved, Levitt himself has hardly
been lying down on the job, using the last two decades to expand
science's flatus horizons even further.
Among the greatest challenges he and the rest of medicine's flatulence
strike force now face is determining whether there is a way to curb
intestinal gas without appreciably restricting a patient's diet. The
solution may well involve enlisting the aid of some of the very
microorganisms that stir things up in the first place. The
Methanobacterium smithii bacterium, Levitt has learned, is a bit of a
microbial specialist, producing not the whole range of gases that make
up flatulence but just methane, a gas molecule made up of four hydrogen
atoms and one carbon atom. As M. smithii manufactures its gas of choice,
it reduces the overall volume of gas surrounding it by condensing four
stray molecules of hydrogen and one of carbon dioxide into a single
molecule of methane and two waters (which are absorbed by the colon),
thus lowering the pressure in the bowels in the process. The problem, as
Levitt has learned, is that M. smithii is one of the least common of all
bowel bacteria, far outnumbered by E. coli and its less fragrant ilk.
Short of running a less than appealing classified ad (HELP WANTED:
Methane Manufacturer; Must Be Willing to Work Indoors), there does not
seem to be any way to increase the population of the desired microbe.
It's only in recent years that we've identified all the bacteria in the
intestines, Levitt says. It will be a while before we can effectively
manipulate them.
On other fronts Levitt has had greater success, most recently developing
a simple Breathalyzer test that can check a patient for incipient
flatulence. To the average nongastroenterologist this seems a bit
counterintuitive, and if Levitt is checking his patients' breath for
flatulence, I wouldn't even ask how he'd propose to conduct dental work.
Levitt, however, insists his system works, explaining that what goes on
at one end of the alimentary autobahn can often reveal a lot about
what's happening at the other.
Flatulence is characterized by an overproduction of a wide range of
gases, including hydrogen, he says. Not all of the gas generated in the
intestines is excreted, however; some of it is absorbed by the blood and
exhaled through the lungs. If you can measure the level of excess
hydrogen in a patient's breath, therefore, you can diagnose a flatulence
problem and perhaps help reverse it.
In a world that has long lionized doctors, Levitt knows that he will
forever labor in something close to obscurity. There will be no prime-
time programs dramatizing flatulence work (St. Anywhere Elsewhere), no
CNN panel shows debating it (Crossfire!), no PBS specials helping raise
money for it (All Creatures Great and Small--But Some From a Distance).
Nevertheless, Levitt remains committed to his discipline of choice, and
well he might. It was no less a physician than Hippocrates who coined
the admonition First, do no harm. Levitt can take some satisfaction in
knowing that his medical specialty is the only one in which this rule
applies as much to the patient as it does to the doctor.
-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Dehoyos, Ramon
Sent: Wednesday, May 23, 2007 7:56 AM
To: [log in to unmask]
Subject: Re: [TN] Flux residue, burnt flux NTC
That report on the Magazine was probably around April 1st No?
-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Bev Christian
Sent: Wednesday, May 23, 2007 8:47 AM
To: [log in to unmask]
Subject: Re: [TN] Flux residue, burnt flux NTC
I would be careful with the latter use of a soldering iron! A well
known gastro-intestinal specialist came to the medical school at the
University of Toronto and gave a very enlightening presentation on
farts. (He generally called them anal emissions.) He said there was
one case where they had been doing surgery in that general area and the
anesthetised patient passed gas as they went to cauterize and the
resulting explosion blew the surgeons back against the wall and tore a 5
inch gash in the poor fellow's large intestine. They had to do
emergency surgery and the guy woke up a tad sorer than he expected.
I read this in the Canadian edition of Time Magazine and it made such an
impression on me I have never forgotten it.
Bev
-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Stadem, Richard D.
Sent: Wednesday, May 23, 2007 8:38 AM
To: [log in to unmask]
Subject: Re: [TN] Flux residue, burnt flux
Quite often, the small amounts of burnt flux or other particulates are
from using the solder irons to perform operations they were not intended
to do, such as shrinking tubing on wires, conformal coat removal, epoxy
removal, performing artistic designs in wood while the boss is not
looking, hemmorhoid removal........
-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Brian Ellis
Sent: Wednesday, May 23, 2007 2:38 AM
To: [log in to unmask]
Subject: Re: [TN] Flux residue, burnt flux
I'm sure that an eminent co-contributor to this forum will tell you, "it
depends". If the flux is truly burnt, i.e., black, this indicates
pyrolysis, which is a fancy word meaning decomposed by heat. Pyrolysis
indicates that the residues have split apart into numerous compounds,
leaving carbon-rich stuff. Elemental carbon can be an electrical
conductor; do you want conducting particles in your assembly? They may
appear fixed in place now, but will they remain so during the life of
the equipment?
More important, WHY are they there? It may be because the operators
don't keep the bits of their irons clean. Do they wipe them on a wet
sponge before each joint is made? It may be that the time/temperature
conditions of the joint being made are far from optimal. It may be lack
of adequate training of the operators. I can't tell. Whatever,
prevention is better than cure; a lttle research into the causes may
give you the answer.
As to flux flow, maybe your solder wire simply has too much flux. Some
manufacturers allow you to choose the percentage. Yes, it is easier to
solder with an excess. It's a compromise.
What you have not told us is the essential information: what kind of
assemblies are you making. You can obviously be more tolerant of
imperfections if you are making toys than if you are making inertial
guidance or satellite systems. Probably you are somewhere between thes
extremes. "It depends"!
Brian
Sue Powers-hartman wrote:
> We fight a constant battle with operators leaving burnt flux in
> joints. Maybe only a small speck, but drives the inspectors nuts. The
> way I read JStd-001D, if they can not see it at referee inspection
power, they have to accept it.
> How dangerous is this burnt flux to the PWB? If it's not seen at
> inspection power and left on the board, what happens. Also, what
about no clean flux?
> Our solder training video says that if no clean flux runs out to far
> and is not heat activated, it can cause problems. Operators watch this
> video, but somehow do not get this. They say that it's no clean, they
can leave it all on.
> I keep saying that this can be a problem, and then they ask me, how
> far out can the flux be away from the joint before it's unacceptable.
>
> Wow, I'm glad I found this forum, I have so many questions to ask you
guys.
> Anyway, thanks for the help on this subject.
>
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