Hardness Units: strong cobb
10623...@compuserve.com
Strong Cobb units are a very old-fashioned unit for the "hardness" of
tablets. This unit was especially used 30 years ago in the english
speaking literature.
Conversion of units: 9.81 N = 1 kp = approx. 1.4 SCE (or SCU).
The term "hardness" means force to break a tablet in a diametral
compression test. Obviously this has nothing to do with the physical term
hardness, but - as often in real life - it's just used in the industrial
environment.
Kind regards
Max Zeller (Max_Z...@compuserve.com; 10623...@compuserve.com)
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Shy
Hi, I'm a chem. eng. student in London and we've got to design a plant
that produces p-xylene. I was wondering if anyone could point me to some
good web sites that may have background information on p-xylene or
general information regarding the environmental and health risks, and
possibly legislation also.
Shy
Uncle Al
It's a chemical. It is deadly, causes cancer, destroys fragile and
endangered ecological niches, and renders thousands of species extinct
every day. The only way it could be worse would be if it contributed to
polyester leisure suits.
Medline (8 million medical references)
http://www.healthgate.com/
http://www.pharminfo.com/pubs/msb/msbmnu.html#msb_contents
http://www.bi.umist.ac.uk/Staff/Academia/RJB/Buffers/Makebuf.html
Big Boppers
http://www.search.com/
http://www.beaucoup.com/engines.html
http://www.albany.net/allinone/
http://www.scicentral.com/
http://www.ozramp.net.au/~toyboy/search.html
http://www.webcom.com/webscout/
http://www.wiredsource.com/wiredsource/
http://nilesonline.com/data/
http://www.smartalex.com/
http://www.tstimpreso.com/hotsheet/
http://www.cnet.com/
http://home.netscape.com/home/internet-search.html
Patent Search
http://patent.cnidr.org/access/text-search-simp.html
http://patent.cnidr.org/access/search-adv.html
http://www.ibm.com/patents
http://patent.womplex.ibm.com/
http://sunsite.unc.edu/patents
http://www.uspto.gov/
http://www.aber.ac.uk/~dgw/patent.htm
http://casweb.cas.org/chempatplus/
http://strategis.ic.gc.ca/sc_innov/engdoc/einnov_search.html
http://muscat.gdb.org/repos/pat/
http://www-sul.stanford.edu/collect/science/patents.html
http://www.spo.eds.com/patent.html
http://www.epo.co.at/epo/
http://www2.jpo-miti.go.jp/
--
Uncle Al Schwartz
Uncl...@ix.netcom.com ("zero" before @)
http://pw1.netcom.com/~uncleal0/uncleal.htm
http://www.ultra.net.au/~wisby/uncleal.htm
http://www.guyy.demon.co.uk/uncleal/uncleal.htm
(Toxic URLs! Unsafe for children, Democrats, and most mammals)
"Quis custodiet ipsos custodes?" The Net!
Eric Lucas
Uncle Al wrote:
> It's a chemical. It is deadly, causes cancer, destroys fragile and
> endangered ecological niches, and renders thousands of species extinct
> every day. The only way it could be worse would be if it contributed to
> polyester leisure suits.
....which it of course does after you it's oxidized to terephthalic acid....
;^)
Eric Lucas
Bruce Hamilton
In article <343539...@ix.netcom.com>
>Shy wrote:
>> Hi, I'm a chem. eng. student in London and we've got to design a plant
>> that produces p-xylene. I was wondering if anyone could point me to some
>> good web sites that may have background information on p-xylene or
>> general information regarding the environmental and health risks, and
>> possibly legislation also.
>It's a chemical.
Yes.
>It is deadly,
No more so than more common HCs such as gasoline.
>causes cancer,
Not directly, possibily if it is an atmospheric pollutant it may
catalyse some smog that could have adverse health effects,
but that man-made p-xylene mainly arises from combustion
sources.
>destroys fragile and endangered ecological niches,
No more than many other HCs, and it it biodegradable.
>and renders thousands of species extinct every day.
No.
>The only way it could be worse would be if it contributed to polyester
>leisure suits.
No, if the methyl groups were lost, it would form benzene, which
is nasty, causes cancer, etc. The use of p-xylene as an industrial
chemical to produce the intermediates ( terephthalic acid or
dimethyl terephthalates ) for polyester fibres is a good reason for
the student to study the manufacture of it.
To the original poster,
The best source of information would be companies that have
plants, probably contacting ICI and BP Chemicals would provide
much of the desired information about both processes and
safety issues. Your library should also have the Kirk Othmer
Encyclopedia of Chemical Technology ( unfortunately the latest
edition ( 4th ) may not yet have reached xylene, but the earlier
edition monograph will point to many useful sources ). A brief
overview will be available in Faith, Keyes, and Clark's
" Industrial Chemicals " ( 4th edition = Wiley, ISBN 0-471-54964-9,
1975 ) which should be available in your library.
McKetta, ( Encyclopedia of Chemical Processing and Design,
J.J.McKetta. Marcel Dekker (1990-) ISBN 0-8247-2497-6 ),
- which all chemical engineering students should become
familiar with - also may not have reached xylenes either, but
will still provide much of the design information in other
monographs. Whilst the WWW has some heath and safety
information, you will be better served to talk nicely to the health
and safety officers at your institution and ask them for the
information.
They should have Sax ( Sax's Dangerous Properties of Industrial
Materials - 9th edition N.I.Sax ( edited by R.J.Lewis Sr. ) Van Nostrand
Reinhold (1996), and also RTECS ( Registry of Toxic Effects of
Chemical Substances. National Institute for Occupational Safety
and Health Cincinnati, Ohio 45226 ). They should also be able
to point you towards the appropriate sections of your local authority
that regulate environmental consequences of industries.
Exhaust the resources of your institution and local industry before
searching further afield.
Bruce Hamilton