Ethyl - product details
Hoffman, Nick N
傻瓜二郎 wrote:
>
> Folks,
> Anybody knows about 2 products by ETHYL Corp, TEL/TML and MMT which are
> additives to gasoline to increase octane level? Any
> papers/documents/books/online material that I can read to find out more
> about the products? Don't suggest me to check their web page, I have,
> but nothing I want is there, so I come to you all.
> /rgds
Try Sci.chem
TEL is probably Tertiary Ethyl Lead and TML the Methyl equivalent.
MMT has me stumped.
Nick Hoffman Mere Geophysicist
"Insert Disclaimer of your choice here"
Joseph S. Merola
In article <33DE86...@NOSPAMbhp.com.au>, "Hoffman, Nick N"
<Hoffman...@NOSPAMbhp.com.au> wrote:
MMT is methylcyclopentadienylmanganesetricarbonyl. This is a very highly
soluble transition metal compound that has anti-knock properties. It was
developed as a replacement for the highly toxic lead compounds such
as tetraethyllead (TEL). Both TEL and MMT also have a poisoning effect on
the catalysts used in catalytic converters, (as well as on people)
so neither are used commercially right now.
--
----------------------------------------------------------------------------
Joseph S. Merola Director of Graduate Education
Department of Chemistry Internet: JME...@VT.EDU
Virginia Tech Voice : (540) 231-4510
Blacksburg VA 24061-0212 FAX : (540) 231-3255
Visit: http://www.chem.vt.edu/chem-dept/merola/merola-group.html
----------------------------------------------------------------------------
Charles B. Schroebel
On Wed, 30 Jul 1997, Hoffman, Nick N wrote:
> =B6=CC=A5=CA=A4G=AD=A6 wrote:
> >=20
> > Folks,
> > Anybody knows about 2 products by ETHYL Corp, TEL/TML and MMT which are
> > additives to gasoline to increase octane level? Any
> > papers/documents/books/online material that I can read to find out more
> > about the products? Don't suggest me to check their web page, I have,
> > but nothing I want is there, so I come to you all.
> > /rgds
>=20
> Try Sci.chem
>=20
> TEL is probably Tertiary Ethyl Lead and TML the Methyl equivalent.
>=20
> MMT has me stumped.
>=20
> Nick Hoffman=09Mere Geophysicist
> =09=09"Insert Disclaimer of your choice here"
>=20
>=20
Hmm, MMT--that's some oddish ether that they add to gasoline to
'oxygenate' it so as to reduce smog in winter time. I always thought that
the best way to add oxygen was as O2 and to add a little spark! Or a
peroxide (yes, I'm dangerous), Somehow they (gov't & their advisors)
believe that if you add partially oxidized organics to gasoline that that
will make <MORE> oxygen available for combustion of the fuel. I guess
they figure that if you balance the budget with s&m you can do the same
with balancing equations. MMT =3D More Money Too.=20
Charles B. Schroebel
(csch...@umabnet.ab.umd.edu)
geht noch ein?
noch ein geht immer noch!
Ian Gay
In article <jmerola-3007...@merola.chem.vt.edu>,
jme...@vt.edu (Joseph S. Merola) wrote:
[snip]
>
>MMT is methylcyclopentadienylmanganesetricarbonyl. This is a very highly
>soluble transition metal compound that has anti-knock properties. It was
>developed as a replacement for the highly toxic lead compounds such
>as tetraethyllead (TEL). Both TEL and MMT also have a poisoning effect on
>the catalysts used in catalytic converters, (as well as on people)
> so neither are used commercially right now.
Except in Canada, where Ethyl are threatening a major law suit to counteract
the ham-handed efforts of the Canadian government to restrict MMT use.
*** To reply by e-mail, remove _nospam from address ***
Craig Keener
Joseph S. Merola wrote:
>
>
> MMT is methylcyclopentadienylmanganesetricarbonyl. This is a very highly
> soluble transition metal compound that has anti-knock properties. It was
> developed as a replacement for the highly toxic lead compounds such
> as tetraethyllead (TEL). Both TEL and MMT also have a poisoning effect on
> the catalysts used in catalytic converters, (as well as on people)
> so neither are used commercially right now.
MMT never saw widespead use in the U.S., but it's been used for years in
Can. where auto emission-control technology has lagged behind the U.S..
I don't know about the rest of the world. MMT also deactivates the
Lambda sensors as well as catalysts BTW, so it'll probably be extinct
everywere soon.
- Craig
Got Root?
Doubt it! MMT can still be purchased in CALIFORNIA automotive shops
(aftermarket lead additives cannot, incidently, although someone could
purchase TEL from a chemical supply, I guess) for specific use in an
automobile engine. And keep in mind, this is the overly-restrictive state
where the gasoline is the worst...
* Less BTUs (less energy to the ground, means more gasoline must be
used to travel the same distance)
* Stinks (MBTE)
* Contaminates ground water (MTBE)
* Corrodes Valve Stem Seals (Dupont Vitron(sp?) incompat with ethers and
alcohols according to journals I have read). This explains the vastly
increased amount of "smoking cars" I have seen lately...
Anyways, if MMT is available here, its not gone from the rest of the civilized
world for a LONG time.... isnt it necessary for cars with non-hardened valve
seats to have some kind of metalic additive anyways?
___
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Bruce Heath
Charles B. Schroebel wrote:
> Hmm, MMT--that's some oddish ether that they add to gasoline to
> 'oxygenate' it so as to reduce smog in winter time.
IXNAY
MTBE (Methyl tert-butyl ether) is the chemical you are thinking of.
MMT is, as a number of others have pointed out, a manganese
organometallic.
BTW, my understanding was that the reason that MMT had never seen light
of day in the US was due to a court case that the EPA and Ethyl were
wrangling over - the EPA refused to grant Ethyl clearance to sell MMT on
tox grounds but, when put to the test, the EPA claims were lacking . The
EPA finally lost that case, so I'm told, but by then the market had
changed so much that Ethyl no longer had a market to sell to. Don't be
suprised if Ethyl sues the EPA for damages.
Rgds,
Bruce Heath
Group Technical Manager
Brisbane Joint Holdings.
Craig Keener
Got Root? wrote:
>
> On Sat, 2 Aug 1997, Craig Keener wrote:
>
> > Joseph S. Merola wrote:
> > >
> > >
> > > MMT is methylcyclopentadienylmanganesetricarbonyl. This is a very highly
> > > soluble transition metal compound that has anti-knock properties. It was
> > > developed as a replacement for the highly toxic lead compounds such
> > > as tetraethyllead (TEL). Both TEL and MMT also have a poisoning effect on
> > > the catalysts used in catalytic converters, (as well as on people)
> > > so neither are used commercially right now.
>
> > MMT never saw widespead use in the U.S., but it's been used for years in
> > Can. where auto emission-control technology has lagged behind the U.S..
> > I don't know about the rest of the world. MMT also deactivates the
> > Lambda sensors as well as catalysts BTW, so it'll probably be extinct
> > everywere soon.
>
> Doubt it! MMT can still be purchased in CALIFORNIA automotive shops
> (aftermarket lead additives cannot, incidently, although someone could
> purchase TEL from a chemical supply, I guess) for specific use in an
> automobile engine. And keep in mind, this is the overly-restrictive state
> where the gasoline is the worst...
You're right. I was only speaking in terms of
commercially-available gasolines containing MMT, as the previous poster
mentioned. Last I knew CA was actually the ONLY state where the EPA had
lifted it's blanket ban on MMT for use in pump fuel, but I don't know if
any's actually been sold there yet. As you've indicated it can also be
found in certain off-the-shelf products too....and not just in
California BTW.
> * Less BTUs (less energy to the ground, means more gasoline must be
> used to travel the same distance)
> * Stinks (MBTE)
> * Contaminates ground water (MTBE)
> * Corrodes Valve Stem Seals (Dupont Vitron(sp?) incompat with ethers and
> alcohols according to journals I have read). This explains the vastly
> increased amount of "smoking cars" I have seen lately...
FWIW, MTBE or ETBE can now be found in most other states with EPA
"non-attainment" areas also, and the concentrations in the RFG are just
as high as in CA. Since RFG isn't going anywhere, I guess it becomes a
matter of choosing the lesser evil. If the oxygenate isn't MTBE or ETBE
then it's either methanol or ethanol (usually the latter). Among it's
other problems, ethanol is much more expensive and receives a hefty
subsidy from our tax dollars to make it competitive, so IMO using
gasahol or alcohol-blended RFG is fine only where cost and
transport-related problems can be kept to a minimum (i.e. the corn
belt). I'd rather see MTBE used in the rest of the country's RFG until
someone proves a definite health or enviromental risk.
> Anyways, if MMT is available here, its not gone from the rest of the civilized
> world for a LONG time.... isnt it necessary for cars with non-hardened valve
> seats to have some kind of metalic additive anyways?
Well, to my knowlege MMT has only ever been sold in a few
countries anyway, and that's including the U.S. and Canadian markets.
Almost all of the third-world continues to use leaded fuels with high
concentrations of TEL, and eliminating lead from fuel is pretty low on
the priority list for a developing nation. After all, it's a might
ridicules to be thinking about such things until people have things like
clean water and you don't have Cholera outbreaks left and right.
Whether those countries now using lead would someday move to MMT
fuel is anybody's guess. It's certainly possible anyway. The reason I
don't think it'll take off anywhere else...and will die out in Canada
soon too...is because it holds the same deactivating effect as lead when
it comes to cat. converters and O2 sensors. Hence it can't be used in
modern vehicles, and the numbers of older vehicles are thinning every
day. With enviromentalists now raising a fuss up there on possible
health effects too, the government will probably decide the issue's
reached a point of diminishing return.
Just my 2 pennies worth...
- C
somebody
>The alkyl leads rapidly became the most cost-effective method of enhancing
>octane. The introduction was not universally acclaimed, as the toxicity
>of TEL soon became apparent.
I don't believe that the toxicity of TEL was ever shown. The metal has
been shown to cause developmental problems in children but I've never seen
studies on lead compounds. I think people just assume that since the
metal is toxic, then the compounds must be toxic. Even in adults, I don't
think the metal is as harmful as people would have you believe. I'd call
it an over-reaction but, if anybody has studies that show otherwise, I
could to change my opinion.
My point is that Brazil, several other contries in South America, a few
countries in Europe and several in the Far East still use TEL in their
gasoline and Ethyl Corp makes a large amount of TEL for the international
market.
David Sullivan
Chem Engr Dept
Univ of TX at Austin
Bruce Hamilton
Bruce Heath <bah...@ozemail.com.au> wrote:
>MMT is, as a number of others have pointed out, a manganese
>organometallic.
>
>BTW, my understanding was that the reason that MMT had never
>seen light of day in the US was due to a court case that the
>EPA and Ethyl were wrangling over - the EPA refused to grant
>Ethyl clearance to sell MMT on tox grounds but, when put to
>the test, the EPA claims were lacking .
No. It was only banned in 1978, and hadn't really been
competitive against the alkyl leads, and so was not
used. The EPA claims were not "lacking", but because
they didn't have evidence based on modern US cars ( after
all, it had been banned ) to support their claim of harm
to emissions systems.
>The EPA finally lost that case, so I'm told, but by then the
>market had changed so much that Ethyl no longer had a market
>to sell to. Don't be suprised if Ethyl sues the EPA for damages.
Whilst Ethyl is sueing in Canada for a different reason, they
are actually now marketing MMT in the USA ( except California ).
EPA have stated that they will closely review the use of MMT, and
will ban it if evidence is found that it does inhibit the
effectiveness of modern emissions systems, or is more toxic than
alternatives. If bets were available, I'd probably go with the
EPA in the long term, and a search of their WWW site should reveal
the press releases from Browner that outline their plans to carefully
scrutinise MMT.
Bruce Hamilton
Eric Lucas
v8man wrote:
>
> Pardon my ignorance, but what is MMT unabbreviated?
> Also, do I understand it correctly that it is a sublstitute for
> tetraethyl lead? Does it lubricate valve seats and increase octane
> numbers or only one of them.
Methylcyclopentadienyl Manganese Tricarbonyl, also known trivially as
methyl cymantrene. Yes, it is largely a substitute for TEL. Manganese
has a truly amazing array of oxidation states available to it, most of
which are separated by one electron: Mn(VII), (Mn(VI)?), Mn(V), Mn(IV),
Mn(III), Mn(II), Mn(I), Mn(0), Mn(-1) and Mn(-3) are all stable under a
variety of real-life, moderate conditions (i.e., not just at 77 K), and
none is separated by a very large energy barrier. Since oxidative
addition of a radical is a one-electron oxidation (i.e., a very low
energy process), this makes its interactions with radicals very facile.
Thus it is a very effective radical scavenger, effectively increasing
octane number.
I guess I was unaware TEL was a valve seat lubricant, so I'm not sure
whether or not MMT is either. Their volatilities (and I believe
viscosities--I've seen MMT, but not TEL) are similar, if that's what
matters.
Eric Lucas
zaph...@mazda.ste.intranet
On Sun, 3 Aug 1997, Craig Keener wrote:
. You're right. I was only speaking in terms of
.commercially-available gasolines containing MMT, as the previous poster
.mentioned. Last I knew CA was actually the ONLY state where the EPA had
.lifted it's blanket ban on MMT for use in pump fuel, but I don't know if
.any's actually been sold there yet. As you've indicated it can also be
.found in certain off-the-shelf products too....and not just in
.California BTW.
I had heard that it was just the other way around, that MMT was federally
legal but that California had banned it in gasoline, presumably because it
can either clog cat. converters or more likely that it damaged oxygen sensors
on cars with feedback systems.
.
.> * Less BTUs (less energy to the ground, means more gasoline must be
.> used to travel the same distance)
.> * Stinks (MBTE)
.> * Contaminates ground water (MTBE)
.> * Corrodes Valve Stem Seals (Dupont Vitron(sp?) incompat with ethers and
.> alcohols according to journals I have read). This explains the vastly
.> increased amount of "smoking cars" I have seen lately...
. FWIW, MTBE or ETBE can now be found in most other states with EPA
."non-attainment" areas also, and the concentrations in the RFG are just
.as high as in CA. Since RFG isn't going anywhere, I guess it becomes a
.matter of choosing the lesser evil. If the oxygenate isn't MTBE or ETBE
.then it's either methanol or ethanol (usually the latter). Among it's
.other problems, ethanol is much more expensive and receives a hefty
.subsidy from our tax dollars to make it competitive, so IMO using
.gasahol or alcohol-blended RFG is fine only where cost and
.transport-related problems can be kept to a minimum (i.e. the corn
.belt). I'd rather see MTBE used in the rest of the country's RFG until
.someone proves a definite health or enviromental risk.
It would have been far more beneficial IMO to have simply used the HC
components of the RFG to see how much that could reduce the problems of urban
pollution. Why? Ca. RFG also makes provisions for other characteristics, one
of the most notable being the elimination of the most and least volatile
portions of the gasoline - so less VOC's escape during gas pump use, from
floatbowls of unregulated carbeurators, etc. This also reduces pollution from
maltuned cars in two ways: much lower likelyhood of vaporlock, which results
in misfires and stalls, and less likelyhood of preignition in cars with
carbon buildup, because the gasoline's octane number is more likely to remain
stable (the most volatile components of gasoline often have the highest
octane ratings. When they evaporate, whats left is lower octane.) Also, the
gasoline components with the highest boiling point may not carbeurate
properly at all, simply going out the tailpipe and/or causing catalytic
converter overheat (eventually disabling the catalyst altogether)...
Granted the middle two are dramatically less important than the first (VOCs
from using the pumps) and last (combustibility) but those changes wouldnt
have had the drawbacks MTBE does.
We'll never know what the air might have looked like now, as peoples valve
stem seals corrode under MTBE exposure... when the new gasoline FIRST came
out, I saw a car IN FLAMES on the side of the 101 freeway at LEAST twice a
week. One day, there were FIVE cars on the sides of the road, four of which
were car fires, one of which was a DUI related accident. Of course, the MTBE
weeded susceptible cars out within a couple of months of introduction, and I
see car fires these days with about the same frequency as before MTBE was
introduced, but there is no denying its corrosive properties... and if anyone
gives me any shit about roadside observations not being good science, they
can check out MTBE in the literature for themselves... :) :) It **IS**
.> Anyways, if MMT is available here, its not gone from the rest of the civilized
.> world for a LONG time.... isnt it necessary for cars with non-hardened valve
.> seats to have some kind of metalic additive anyways?
. Well, to my knowlege MMT has only ever been sold in a few
.countries anyway, and that's including the U.S. and Canadian markets.
.Almost all of the third-world continues to use leaded fuels with high
.concentrations of TEL, and eliminating lead from fuel is pretty low on
.the priority list for a developing nation. After all, it's a might
.ridicules to be thinking about such things until people have things like
.clean water and you don't have Cholera outbreaks left and right.
Surely you jest! TEL was never eliminated because of lead's toxic effects on
human beings! TEL was eliminated because of its toxic effects on catalytic
converters, which are necessary to keep rich people's views of the California
Sunset pristine. Only after catalytic converter type cars dominated the
market did anyone start to think about all the lead in kids lungs and
such...
Its sad, but its also true: whenever a big government agency or corporation
does something "for the environment", it rarely is. Consider the fact that
the M100 (methanol) sold at the pump at Arco here in my city requires a
special credit card from the state - but you can buy extremely toxic gasoline
no matter what your age, provided you have a container for it...
Theres no money in producing a methanol burning car, because theres not going
to be the need for ultra-expensive smog equipment and computer controls on
the car... such a car wouldnt be "guaranteed to expire" even if regularly
maintained because it would easily pass smog checks. Like the everlasting
light bulb, the methanol powered car seems to be a pipe dream (despite the
fact that methanol is about $1.00 a gallon at the pump, 102 octane rating,
and has enough BTU to make it quite cost effective -- considering that
power-robbing smog equipment wouldnt be needed) Sure methanol has a lower
BTU, but once you realize the fact that the same displacement of air burns
that much MORE methanol, its a damned good fuel!
. Whether those countries now using lead would someday move to MMT
.fuel is anybody's guess. It's certainly possible anyway. The reason I
.don't think it'll take off anywhere else...and will die out in Canada
.soon too...is because it holds the same deactivating effect as lead when
.it comes to cat. converters and O2 sensors. Hence it can't be used in
.modern vehicles, and the numbers of older vehicles are thinning every
.day. With enviromentalists now raising a fuss up there on possible
.health effects too, the government will probably decide the issue's
.reached a point of diminishing return.
... at which point those remaining cars without hardened valve seats will
become gross polluters until they cease to function altogether.
Over-The-Counter MMT should always remain available to prevent this.
Instead of this carbon-tax stuff being proposed that will hopefully never
happen (paying underdeveloped countries for rights to use OUR resources?
paying underdeveloped countries NOT to develop? Sounds like a formula to make
the whole world experience the propserity and economic health of ethiopia..)
... perhaps our charity money would be better spent partially subsidizing MMT
as a lead alternative in other countries? We wouldnt even have to throw money
into other economies - just subsidize american companies producing MMT for
export as a fuel additive. After all, MMT is nothing but good
environmentally for a car built along the same designs as, say, a 1960
American car!
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v8man
Pardon my ignorance, but what is MMT unabbreviated?
Also, do I understand it correctly that it is a sublstitute for
tetraethyl lead? Does it lubricate valve seats and increase octane
numbers or only one of them.
Cheers.
Bruce Hamilton
In article <somebody-040...@luke.che.utexas.edu>
some...@che.utexas.edu (somebody) writes:
>>The alkyl leads rapidly became the most cost-effective method of enhancing
>>octane. The introduction was not universally acclaimed, as the toxicity
>>of TEL soon became apparent.
>I don't believe that the toxicity of TEL was ever shown.
Nonsense, the parts of the FAQ that you carefully omitted *pointed* to
references on the subject , and I'll include some others also from the
FAQ.
Review the early history of the manufacture of TEL in theearly 1920s, and a
large number of workers were harmed, and some killed, before all the
appropriate precautions were taken.
> The metal has been shown to cause developmental problems in children
> but I've never seen studies on lead compounds. I think people just assume
> that since the metal is toxic, then the compounds must be toxic. Even in
> adults, I don't think the metal is as harmful as people would have you
> believe. I'd call it an over-reaction but, if anybody has studies that show
>otherwise, I could to change my opinion.
>My point is that Brazil, several other contries in South America, a few
>countries in Europe and several in the Far East still use TEL in their
>gasoline and Ethyl Corp makes a large amount of TEL for the international
>market.
The worldwide market for alkyl leads has continued to decline, and the
FAQ also points to articles on the reason why. I have pointed you
towards articles on the subject, and yet you still say you want to see
studies, when you apparently haven't even read the articles - which
provide plenty of references to both the historical literature and the
toxicology. Alkyl lead compounds are very toxic, it's been known
since their large scale manufacture in the 1920s - when a huge
public health debate raged over whether they should even be used.
Bruce Hamilton
Once again, the FAQ extract, with the references:-
The alkyl leads rapidly became the most cost-effective method of enhancing
octane. The introduction was not universally acclaimed, as the toxicity
of TEL soon became apparent, and several eminent public health officials
campaigned against the widespread introduction of alkyl leads [25].
Their cause was assisted by some major disasters at TEL manufacturing
plants, and although these incidents were mainly attributable to a failure
of management and/or staff to follow instructions, they resulted in a
protracted dispute in the chemical and public health literature that even
involved Midgley [25,26]. We should be careful retrospectively
applying judgement to the 1920s, as the increased octane of leaded gasoline
provided major gains in engine efficiency and lower gasoline prices.
25. Dying for Work: Workers' Safety and Health in 20th Century America.
Edited by D.Rosner & G.Markowitz.
Indiana University Press. ISBN 0-253-31825-4 (1987).
26. Tetraethyl Lead Poison Hazards
T.Midgley,Jr.
Ind. Eng. Chem., v.17 p.827-828 (1925).
27. Modern Petroleum Technology - 5th edition.
Editor, G.D.Hobson.
Wiley. ISBN 0 471 262498 (1984).
- Chapter 20. K.Owen.
29. Role of Lead Antiknocks in Modern Gasolines.
A.J.Pahnke and W.E.Bettoney
SAE Paper 710842 (1971) 32pp.
29a. A Heavy Responsibility.
F.Pearce
New Scientist p.12-13. 27 July 1996
70. The Rise and Fall of Lead in Petrol.
I.D.G.Berwick
Phys. Technol., v.18 p.158-164 (1987)
71. Genotoxic and Carcinogenic Metals: Environmental and Occupational
Occurance and Exposure.
Edited by L.Fishbein, A.Furst, M.A.Mehlman.
Princetown Scientific Publishing. ISBN 0-911131-11-6 (1987)
"Lead" p.211-243.
Bruce Hamilton
Eric Lucas <ealucas*antispam*@ix.netcom.com> wrote:
>Methylcyclopentadienyl Manganese Tricarbonyl, also known trivially as
>methyl cymantrene.
[ discussion on radical reactions deleted ]
>Thus it is a very effective radical scavenger, effectively increasing
>octane number.
The effectiveness does also depend on the hydrocarbon composition of
the fuel, some extracts from the Gasoline FAQ below help note the
differing mechanisms of oxygenate and alkyl lead octane enhancers.
[ begine extract ]
The octane rating of hydrocarbons is determined by the structure of the
molecule, with long, straight hydrocarbon chains producing large amounts of
easily-autoignitable pre-flame decomposition species, while branched and
aromatic hydrocarbons are more resistant. This also explains why the octane
ratings of paraffins consistently decrease with carbon number. In real life,
the unburnt "end gases" ahead of the flame front encounter temperatures up
to about 700C due to compression and radiant and conductive heating, and
commence a series of pre-flame reactions. These reactions occur at different
thermal stages, with the initial stage ( below 400C ) commencing with the
addition of molecular oxygen to alkyl radicals, followed by the internal
transfer of hydrogen atoms within the new radical to form an unsaturated,
oxygen-containing species. These new species are susceptible to chain
branching involving the HO2 radical during the intermediate temperature
stage (400-600C), mainly through the production of OH radicals. Above 600C,
the most important reaction that produces chain branching is the reaction of
one hydrogen atom radical with molecular oxygen to form O and OH radicals.
...
The addition of additives such as alkyl lead and oxygenates can
significantly affect the pre-flame reaction pathways. Antiknock additives
work by interfering at different points in the pre-flame reactions, with
the oxygenates retarding undesirable low temperature reactions, and the
alkyl lead compounds react in the intermediate temperature region to
deactivate the major undesirable chain branching sequence [21,22].
There are huge number of chemical mechanisms involved in the pre-flame
reactions of gasoline combustion. Although both alkyl leads and oxygenates
are effective at suppressing knock, the chemical modes through which they
act are entirely different. MTBE works by retarding the progress of the low
temperature or cool-flame reactions, consuming radical species, particularly
OH radicals and producing isobutene. The isobutene in turn consumes
additional OH radicals and produces unreactive, resonantly stabilised
radicals such as allyl and methyl allyl, as well as stable species such as
allene, which resist further oxidation [21,22].
[ end extract ]
>I guess I was unaware TEL was a valve seat lubricant, so I'm not sure
>whether or not MMT is either. Their volatilities (and I believe
>viscosities--I've seen MMT, but not TEL) are similar, if that's what
>matters.
No it's not. Also from the Gasoline FAQ
8.8 Can I used unleaded on older vehicles?
Yes, providing the octane is appropriate. There are some older engines that
cut the valve seats directly into the cylinder head ( eg BMC minis ). The
absence of lead, which lubricated the valve seat, causes the very hard
oxidation products of the exhaust valve to wear down the seat. This valve
seat recession is usually corrected by installing seat inserts, hardening
the seats, or use of specific valve seat recession protection additives
( such as Valvemaster ). .....
8.9 How serious is valve seat recession on older vehicles?
The amount of exhaust valve seat recession is very dependent on the load on
the engine. There have been several major studies on valve seat recession,
and they conclude that most damage occurs under high-speed, high-power
conditions. Engine load is not a primary factor in valve seat wear for
moderate operating conditions, and low to medium speed engines under
moderate loads do not suffer rapid recession, as has been demonstrated
on fuels such as CNG and LPG. Under severe conditions, damage occurs rapidly,
however there are significant cylinder-to-cylinder variations on the same
engine. A 1970 engine operated at 70 mph conditions exhibited an average
1.5mm of seat recession in 12,000km. The difference between cylinders has
been attributed to different rates of valve rotation, and experiments have
confirmed that more rotation does increase the recession rate [29].
The mechanism of valve seat wear is a mixture of two major mechanisms. Iron
oxide from the combustion chamber surfaces adheres to the valve face and
becomes embedded. These hard particles then allow the valve act as a grinding
wheel and cut into the valve seat [115]. The significance of valve seat
recession is that should it occur to the extent that the valve does not seat,
serious engine damage can result from the localised hot spot.
There are a range of additives, usually based on potassium, sodium or
phosphorus that can be added to the gasoline to combat valve seat recession.
As phosphorus has adverse effects on exhaust catalysts, it is seldom used.
The best long term solution is to induction harden the seats or install
inserts, usually when the head is removed for other work, however additives
are routinely and successfully used during transition periods.
[ end extract ]
The lubricating effect occurs because some of the lead does deposit on
the cooler seat as the exhaust gases exit, and that provides lubrication
that prevents the recession - it can take a few weeks for the protective
film to be consumed once leaded fuels are no longer used.
I'm not certain if MMT would provide the same protection, however there
are several additives that are routinely used with unleaded fuels that
are also compatible with catalysts.
Bruce Hamilton
Jim Davidson
Bruce Hamilton wrote:
> >I don't believe that the toxicity of TEL was ever shown.
>
> Nonsense, the parts of the FAQ that you carefully omitted *pointed* to
> references on the subject , and I'll include some others also from the
> FAQ.
However, the toxicity of tetra ethyl lead is not the only relevant
issue. When tetra ethyl led is burned in an engine, it forms lead
oxide, which is not especially desirable but is also not especially
toxic. However, ethylene dibromide is another typical additive, often
used in combination with tetra ethyl lead which burns to form products
which combine with lead oxide to form lead bromide. Lead bromide is
toxic and volatile, and is one of the more troublesome of the compounds
produced from the burning of leaded gasoline.
However, leaded gas also tends to poison the catalytic converter which
are supposed to oxidize unburned hydrocarbons, carbon monoxide, and
nitrogen oxides. Of course, the catalytic converter contains platinum
group metals that also combine readily with lead, and thereby lose their
catalytic characteristics with regard to the pollutants they are
supposed to control. Of course, whether the concentration of noxious
hydrocarbons, CO, and NOx in the catalytic converter is actually an
improvement, given the sometimes awkward record of companies which
recover the platinum group metals from catalytic converters...well,
that's another can of worms, isn't it?
> Review the early history of the manufacture of TEL in theearly 1920s, and a
> large number of workers were harmed, and some killed, before all the
> appropriate precautions were taken.
I find this argument entirely specious. Obviously when the manufacture
of a new compound is developed, there can be some risk. However, when
appropriate precautions were taken, as they were for dozens of years
during the period from the 1930s to the 1970s when leaded gasoline was
commonplace, a vast quantity of tetra ethyl lead was produced without
harm to large numbers of workers.
Of course, the additives for unleaded gasoline have not been discussed.
Safety issues involved in the production of these alternative additives
as well as the pollution hazards of compounds they create when burned in
an engine have been thoroughly underevaluated.
A person far more cynical than I would note that the patents on leaded
gasoline had run out, as well as on the various lead-related gasoline
additives, by the time the phase out of tetra ethyl lead was in full
swing. Might it have been an interested chemical company or two that
wanted their new additives to have a protected and preferred place in
the market who were the driving force behind the adoption of the
unleaded gasoline laws?
In similar vein, it has been rather more obvious that the major chemical
companies have sought to phase out freon and encouraged the rather
bizarre "environmental" policies on this chemical's use. While it has
yet to be demonstrated to my satisfaction that ozone in the upper
atmosphere is more greatly threatened by the fluorocarbons in air
conditioning systems such as freon, than, say, by the chlorine compounds
deposited into the upper atmosphere by the space shuttle's solid rocket
boosters, or by the chlorine compounds found in volcanic ash deposited
into the upper atmosphere by such events as Mt. Pinatubo's eruption, it
is quite clear to me that if freon is a danger, keeping it sealed in air
conditioning and refrigeration systems is far preferable to purging
those systems to replace freon with some alternative compound.
Are the replacement chemicals for freon really that much safer? Or are
they just more thoroughly protected by patents and thus more lucrative?
Is the environment really best served by the wholesale purging of freon
from cooling equipment, or is it just possible that the profits of
certain chemical companies are best served thereby? I leave these
questions as an exercise for the reader.
> The worldwide market for alkyl leads has continued to decline, and the
> FAQ also points to articles on the reason why.
And do any of these articles suggest that some companies have enhanced
their profits by supporting legislation that prohibits the compounds
produced by their competitors? How...curious.
> Their cause was assisted by some major disasters at TEL manufacturing
> plants, and although these incidents were mainly attributable to a failure
> of management and/or staff to follow instructions, they resulted in a
> protracted dispute in the chemical and public health literature that even
> involved Midgley [25,26].
Well, gosh, if Midgley got involved, it must have been serious. Ack.
"These incidents were mainly attributable to a failure...to follow
instructions...." Yep. That says it all. Tetra ethyl lead and other
chemicals are safe to produce and handle if you follow safety
instructions. Just as skydiving is a safe sport, with more successful
landings for parafoils as a percentage of attempts than for any aircraft
on the market. Yet, skydiving is unsafe when safety instructions aren't
followed. I don't think these accidents in the 1920s prove very much
about the safety of using tetra ethyl lead.
> We should be careful retrospectively
> applying judgement to the 1920s, as the increased octane of leaded gasoline
> provided major gains in engine efficiency and lower gasoline prices.
Right. So the issue wasn't some callous disregard for plant safety.
Obviously, safety precautions had been developed and experience taught
that they needed to be obeyed. More importantly, with higher octane,
more efficient engines, and lower gasoline prices, more people around
the world were able to better afford higher quality automobiles. The
economic impact of the automobile was tremendously positive on a
cost/benefit basis.
Malthus warned that London would be neck deep in horse manure by the
early decades of the 20th Century. While we can argue the extent to
which tetra ethyl lead compounds are beneficial, it is clear that doing
away with the proximity of great piles of horse dung to major urban
populations had very positive public health benefits. A few people may
have died in the 1920s due to poor adherence to safety procedures, and a
few more may have had their lifespans shortened during the balance of
this century, but dozens and hundreds have died from diseases and
infections carried by insects which live off of manure, hundreds have
died from tetanus and lockjaw from manure-infected puncture wounds, and
thousands have died from intestinal disorders related to runoff from
dung getting into public water supplies.
It isn't always clear what objective public health and environmental
safety activists are trying to achieve. While it is widely recognized
that it isn't possible to create a world without some risk of death,
that seems to be the insistent clamoring from certain circles. On the
whole, I'd rather have the risks from tetra ethyl lead, or the risks
from the unleaded gasoline additives, than have mountains of horse dung
in every major city.
Free Yourself,
Jim Davidson
http://www.rwintl.com/
Bruce Hamilton
Jim Davidson <davi...@net1.net> wrote:
>Bruce Hamilton wrote:
>> >I don't believe that the toxicity of TEL was ever shown.
>> Nonsense, the parts of the FAQ that you carefully omitted *pointed* to
>> references on the subject , and I'll include some others also from the
>> FAQ.
>
>However, the toxicity of tetra ethyl lead is not the only relevant
>issue. When tetra ethyl led is burned in an engine, it forms lead
>oxide, which is not especially desirable but is also not especially
>toxic.
No. What is formed is a range of lead compounds and metallic lead
- depending on the combustion conditions. These compounds will
deposit in the combustion chamber, exhaust manifold, and exhaust
system and the engine soon ceases to function. As the FAQ notes,
right up until the 1950s it was common to find balls of metallic
lead rolling around inside the muffler because the scavenger
formulation was not optimum.
>However, ethylene dibromide is another typical additive, often
>used in combination with tetra ethyl lead which burns to form products
>which combine with lead oxide to form lead bromide. Lead bromide is
>toxic and volatile, and is one of the more troublesome of the compounds
>produced from the burning of leaded gasoline.
Either ethylene dichloride and/or ethylene dibromide can, and are,
used as scavengers usually around equal amounts of each, and it is
only in aviation gasoline where ethylene dibromide is solely specified
( to reduce the corrosion of aluminium ).
[Stuff about catalyst poisoning deleted, all in the FAQ, along which
other toxic emissions such as the organohalogens like dioxin ]
>> Review the early history of the manufacture of TEL in the early 1920s,
>> and a large number of workers were harmed, and some killed, before all
>> the appropriate precautions were taken.
>I find this argument entirely specious. Obviously when the manufacture
>of a new compound is developed, there can be some risk.
Well I'm stunned. I point to several reasonably-accessible
publications and, rather than read them and comment, you
instead " find this argument entirely specious "
Let's just review some of that "specious" history, most of
which filled the American Journal of Public Health during
the 1920s. This was not your typical new industrial chemical...
1910s - Alice Hamilton had shown that lead was an industrial toxin,
and a major hazard to exposed workers.
1921 - 9 December, Midgley discovers the anti-knock properties of TEL.
1922 - W.M.Clark, a chemistry professor wrote to the Assistant Surgeon
General at the Public Health Service warning of "a serious menace
to public health " and expresseed concern about the accumulation
of the toxin near roads " on busy thoroughfares it is highly
probable that the lead oxide dust will remain in the lower stratum".
There were already reports available to him about incidents involving
TEL in laboratories, although the researchers understood the
potential hazards.
1922 The PHS couldn't afford to undertake an investigation into TEL, so
they wrote to Ethyl Corp. asking what research they had undertaken.
Thomas Midgley replied that no experiments had been performed.
1923 - 1st February, First gasoline containing TEL additive marketed.
1923 Ethyl Corp. realised they needed an "independant" assessment, so
they contracted the Bureau of Mines, however they specified that
no interim results should be made public by either party.
1924 July, Graham Edgar ( the inventor of Octane rating scale ) of Ethyl
wrote to the American Medical Association claiming that the BoM
research showed " that there is no danger of acquiring lead poisoning
through even prolonged exposure to exhaust gases of cars using Ethyl
fluid ", even though the preliminary report had not been released.
1924, 26 October Five workers die, thirty others show neurological
symptoms of organic lead poisoning, after an accident at the
Standard Oil Research Labs. Of the 49 workers and researchers in
the TEL plant, over 80% were severely poisoned ( went insane ).
The newspapers started to call TEL the " Looney Gas ".
As public health and labour officials ( Federal and State ) started
to investigate, they demonstrated, and Ethyl admitted " that it was
known that this gas had collected a previous toll of death and
insanity.. ".
1924 New York City, Philadelphia, and other municipalities and states
banned the sale of leaded gasoline.
1924 Midgley takes a prolonged vacation to cure himself of lead poisoning.
1925 Evidence is discovered that 2 people had previously died of
lead poisoning at GM Research at Dayton, and four more at the
DuPont site at Deeepwater. The New York Times discovered that there
were 300 cases of lead poisoning at Deepwater over the previous two
years.
1925 The BoM report is issued after long, protracted negotiations which
had resulted in Ethyl Corp providing funds on the condition that they
had to approve all released reports. The released report was roundly
criticised by the public and the health officials as the claims of no
potential harm were obviously incorrect.
1925 Midgely blames all the incidents on careless workers. When questioned
by a reporter, he responds by washing his hands in some Ethyl fluid,
and states " I'm taking no chances whatever. Nor would I take any
chances doing that every day ". History doesn't record if he had
another extended vacation.
1925 20 May, the Surgeon General calls a conference of all the leading
participants in the TEL debate. Kettering, Midgley and the industry
supportors were on one side, and the opponents were lead by Alice
Hamilton, the country's foremost expert on lead poisoning, and
Yandell Henderson, of Yale University. After the conference, Ethyl
suspended all manufacture and distribution of TEL until an
"independent' investigation had been performed. Because Ethyl claimed
that TEL was essential for the economic well-being of the nation, the
investigation was only given a few months to examine and report.
1925, December. The report was predictable. they had examined 252 workers,
mostly garage attendents and chauffeurs, of which approx 20% were
controls, and another 20+% from inorganic lead dust industries. They
found no good grounds for prohibiting the use of TEL, but recommended
that more extensive government-funded studies be performed. Ethyl Corp.
quickly publicised the first, and no government-funded studies were
performed, with all susseqyuent studies were performed by scientists
funded by Ethyl Corp.
>However, when
>appropriate precautions were taken, as they were for dozens of years
>during the period from the 1930s to the 1970s when leaded gasoline was
>commonplace, a vast quantity of tetra ethyl lead was produced without
>harm to large numbers of workers.
You are claiming that there were no further alkyl lead fatalities
or poisoning during that period, please provide the reference, as
I've got publications that clearly show otherwise.
Have you ever worked with pure TEL?, I have worked with 100ml
quatities. Let me describe what my employer considered appropriate.
First, a visit to the local occupational health specialist to check
my general state of health and take hair and blood samples for
background lead levels. These were repeated weekly, up until
one month after the last exposure, with asix monthly followup check.
First you strip, shower, and then you put on disposable cotton
undergarments. Next you put on heavy PVC trousers and a heavy
PVC jacket, buttoned and flap sealed at the back. Next follows
gumboots which are sealed inside the PVC trouser legs via ties.
Next is a positive pressure, filtered air supply hood with airline,
or a full BA system if high mobility is required. Then surgical
gloves followed by heavy PVC gauntlets that are sealed into the
sleeves. When you have finished, you pass through a high pressure
shower to thoroughly rinse the outer layers before starting to
change. At the completion of the work all clothing was disposed
of as heavy-metal contaminated.
Many of the above ( selection of healthy workers, daily monitoring,
rubber gloves, gas masks, and not wearing working clothes away from
the plant ) were already in place at the Baywater plant in the early
1920s before the poisoning.
Now, just in case you believe the above is an over-reaction, consider
the recent tragic case where an eminent researcher ( Karen E Wetterhahn )
spilt "one to a few drops" of dimethylmercury. The compound permeated
her latex gloves and was absorbed into her blood and she died. Details
can be found in C&EN 12 May 1997 p7,and C&EN 16 June 1997 p11,12.
Compounds like TEL,TML, and DMM are highly toxic, and the only reason
>Of course, the additives for unleaded gasoline have not been discussed.
>Safety issues involved in the production of these alternative additives
>as well as the pollution hazards of compounds they create when burned in
>an engine have been thoroughly underevaluated.
Well, if you had bothered reading some of the Gasoline FAQ, and
the references cited therein, you would know that the pollution
hazards of the compounds when burnt were extensively investigated
in the Auto/Oil programme, with the notable exception being the
potential for global carbonyl pollution - which is difficult and
expensive.
The problems lie more with the pollution problems due to the
different water solubility of the oxygenates and the inhalation
hazards of the oxygenates in the fuel during refuelling, rather
than combustion properties. The major issue is whether they are
actually effective in reducing pollution.
>A person far more cynical than I would note that the patents on leaded
>gasoline had run out, as well as on the various lead-related gasoline
>additives, by the time the phase out of tetra ethyl lead was in full
>swing.
What patents?. The TEL discovery was made on 9 Dec 1921, marketed on
1 February 1923, and TML was first marketed in 19660 by Standard Oil
Company of California. Give us the patent numbers, as a cynical
person like myself might assume you have no evidence.
>Might it have been an interested chemical company or two that
>wanted their new additives to have a protected and preferred place in
>the market who were the driving force behind the adoption of the
>unleaded gasoline laws?
Come on, the battle to retain lead in the early 1970s is well
documented. Associated Octel and Ethyl were unable to discover
a viable lead-tolerant exhaust catalyst, and there were no obvious
alternative octane enhancers that were viable, hence the octane
rating of the fuel dropped dramatically. For your claim to be
valid, there had to be an alternative available - there wasn't.
Bruce Hamilton
.
Gene Fuss
Jim Davidson wrote:
<lots of snip>
> In similar vein, it has been rather more obvious that the major chemical
> companies have sought to phase out freon and encouraged the rather
> bizarre "environmental" policies on this chemical's use. While it has
> yet to be demonstrated to my satisfaction that ozone in the upper
> atmosphere is more greatly threatened by the fluorocarbons in air
> conditioning systems such as freon, than, say, by the chlorine compounds
> deposited into the upper atmosphere by the space shuttle's solid rocket
> boosters, or by the chlorine compounds found in volcanic ash deposited
> into the upper atmosphere by such events as Mt. Pinatubo's eruption, it
> is quite clear to me that if freon is a danger, keeping it sealed in air
> conditioning and refrigeration systems is far preferable to purging
> those systems to replace freon with some alternative compound.
To the best of my knowledge, the freon still sealed in the A/C and
refrigeration systems is not being phased out. The materials to
recharge what has LEAKED from those systems (and will likely continue to
leak unless the leak was truly fixed - a condition not met in many
repairs) is what is being phased out. I hadn't heard of people purging
the freon and replacing it with an alternative compound just for the
heck of it; the purge/replace occurs when the freon leaked out due to
worn/cracked compressor seals, leaky fittings, cracks in
tubing/hardware.
Others are more qualified than I to speak to the relative amounts of
stratospheric chlorine and relative contribution to stratospheric ozone
destruction due to chlorine from freons, solid rocket boosters and
volcanic eruptions. I do remember reading that the lbs/day of freons
released/leaked into the atmosphere was a very large number in the 80's
and early 90's.
>
> Are the replacement chemicals for freon really that much safer?
There are two safers: safer for human toxicity and 'safer' for the ozone
layer.
Human toxicity-wise the freons (aka CFC's - chlorofluorocarbons) are
pretty benign. The PFC's (perfluorocarbons) are pretty benign but
contribute to global warming. The HCFC's (hydrogenated
chlorofluorocarbons) are worse toxicity; the exposure limits on some are
pretty tight. The HFC's (hydrogenated fluorocarbons) are reported to be
not as toxic as HCFC's. The hydrocarbon-based organic replacements
(cleaning application substitutes) are a mixed bag for human toxicity,
and they have to be selected more specifically for each application than
the freons (both for cleaning efficiencies and for [some compounds]
flammability reasons).
As for 'safer' for the ozone layer: The HFC's and HCFC's do break down
/ deactivate more readily in the lower atmosphere, so they contribute
much less to stratospheric ozone destruction than the freons.
> Or are they just more thoroughly protected by patents and thus more lucrative?
> Is the environment really best served by the wholesale purging of freon
> from cooling equipment, or is it just possible that the profits of
> certain chemical companies are best served thereby? I leave these
> questions as an exercise for the reader.
The chemical companies (especially DuPont and Allied) fought the freon
phase out vigorously at first, and when they found themselves on the
losing end of the argument they decided to turn the lemons into
lemonade. I think economic survival played a stronger part than any
'business conspiracy theory'.
Some of the early replacement compounds for freon (CFC-113) sent to me
for my cleaning applications were economic failures for the chemical
companies and the companies trying to adapt equipment to use them, as
well as being impractical for my needs. The replacement chemicals
effort for cooling/refrigeration systems also exacted high engineering
and reliability testing costs. The transition hasn't been 'easy' for
anyone. I guess you had to be there and live through it to feel the
pain.
<lots more snipped>
> Free Yourself,
>
> Jim Davidson
> http://www.rwintl.com/
I feel you are sincere in your beliefs. I hope you are willing to
broaden your viewpoint to see beyond the business conspiracy theory.
Gene Fuss
Bruce Hamilton
Jim Davidson <davi...@net1.net> wrote:
>Bruce Hamilton wrote:
>> Jim Davidson wrote:-
>>> When tetra ethyl led is burned in an engine, it forms lead
>>> oxide, which is not especially desirable but is also not
>>> especially toxic.
Note this claim is discussing "tetra ethyl lead ", not formulated
lead additive ( with scavengers ) - such as " Ethyl fluid ".
>> No. What is formed is a range of lead compounds and metallic lead
>> - depending on the combustion conditions. These compounds will
>> deposit in the combustion chamber, exhaust manifold, and exhaust
>> system and the engine soon ceases to function. As the FAQ notes,
>> right up until the 1950s it was common to find balls of metallic
>> lead rolling around inside the muffler because the scavenger
>> formulation was not optimum.
>One of those compounds is lead oxide.
Yes it is, and it is also non-volatile, and thus deposits in the
engine, manifold, and exhaust as above. That's the reason why TEL
was formulated with scavengers when added to gasoline. As far as
I'm aware, the investigation of scavengers immediately followed the
discovery of the anti-knock properties of TEL and by 1928 fuels
contained both ethylene dibromide and ethylene dichloride, thus
there was only a four year period when TEL could have been
marketed without scavengers. Your reference has yet to
be supplied that indicates lead oxide deposits in significant
quantities on the seat from leaded gasolines. One reference I have
states that lead halides deposit on the seat and oxides on the valve.
( " Exhaust Valve Recession with low-lead gasolines " Automotive
Engineering v.95 n.11 p.72-76 (1987).
>"Soon" seems to be an ill-defined term. I know of internal combustion
>engines that have operated for 40 years on leaded gasoline.
Strange, please cite your sources, as there was a maximum period
of four years when tetra ethyl lead ( the subject of your claim )
was used without scavengers. I suspect that you have now changed
your claim to "leaded gasoline" - which includes scavengers, and
thus supports my claim.
>> You are claiming that there were no further alkyl lead fatalities
>> or poisoning during that period, please provide the reference, as
>> I've got publications that clearly show otherwise.
>No, I made no such claim.
>Your documentation clearly shows, as you indicate, that with proper
>precautions, vast quantities of TEL were produced without harm to
>large numbers of workers.
Nowhere does my documentation claim that. TEL wasn't produced
worldwide " from the 1930s to the 1970s ... with proper
precautions " as you claim. There were hundreds of incidents
involving serious exposure of workers to TEL, including eight
fatalities in a single US incident more than thirty years after
the introduction of TEL ( " Tetraethyl Lead Poisoning Incident with
Eight Deaths " Am.Ind.Hyg.Assn.J. v.21 p515-517 (1960)). There were
incidents virtually every year, even though the known toxicity of
TEL had produced increasingly sophisticated production systems that
minimised the numbers of workers potentially exposed, and extensive
worker training was given.
Disproportionate numbers of workers were harmed by TEL - compared
to those handling and manufacturing of most other chemicals that
were also routinely available to the general public. The industry
expended great effort to minimise public concern and government
toxicological research during the period and yet, unlike asbestos,
the evidence of toxicity was comprehensive and compelling.
I finished my history of alkyl lead in 1928, but if you want to
learn about how the industry used several "scientific institutes",
including the " Mellon Institute " and the " Charles F.Kettering
Foundation and Kettering Laboratory of Applied Physiology " to
monopolise the public health research on TEL and lead hazards, then I
suggest you read " Hegemony through Science: Information Engineering
and Lead Toxicology, 1925-1965 " W.Graebner. Chapter 9 of
Dying for Work: Workers' Safety and Health in Twentieth-Century
America. Indiana University Press ISBN 0-253-31825-4 (1987).
TEL was not, and is not, a typical industrial chemical, and
is highly toxic. The production and distribution cost the lives
and health of many workers. Whilst the USA banned alkyl leads
because of their adverse effect on exhaust catalysts, other
countries ( such as the UK ) severely curtailed their use of alkyl
leads because of the adverse health effects of lead emissions,
especially on children.
TEL was required in the 1920s and 1930s to progress the development
of the internal combustion engine, and to efficiently produce
gasoline, and it served those purposes admirably well. However,
the dark side was the legacy of death and madness that persisted
right up until the 1970s, when public health officials finally
realised that the costs far outweighted the benefits, and that
society would benefit from the removal of alkyl leads.
Bruce Hamilton
Jim Davidson
Bruce Hamilton wrote:
> No. What is formed is a range of lead compounds and metallic lead
One of those compounds is lead oxide.
> - depending on the combustion conditions. These compounds will
> deposit in the combustion chamber, exhaust manifold, and exhaust
> system and the engine soon ceases to function.
"Soon" seems to be an ill-defined term. I know of internal combustion
engines that have operated for 40 years on leaded gasoline.
> Well I'm stunned. I point to several reasonably-accessible
> publications and, rather than read them and comment, you
> instead " find this argument entirely specious "
Be stunned, then. You are the one who says that workers were harmed
before appropriate cautions were taken. Why should that surprise
anyone? Why is arguing that such a situation is especially interesting
to anyone anything other than specious?
> You are claiming that there were no further alkyl lead fatalities
> or poisoning during that period, please provide the reference, as
> I've got publications that clearly show otherwise.
No, I made no such claim. Your documentation clearly shows, as you
indicate, that with proper precautions, vast quantities of TEL were
produced without harm to large numbers of workers. Or are you saying
that every worker who ever worked on the production of TEL was harmed?
Jim
http://www.rwintl.com/