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Re: HyperSolv -Reply



In a message dated 97-09-16 00:27:20 EDT, you write:

<< >What is the flash point of n-propyl bromide?
 
 The flash point for 1-bromopropane (CAS No. 106-94-5) is 21 C (closed cup)
 (see : http://safety.hoseo.ac.kr/MSDS/B/1-BROMOPROPANE).  The Environmental
 Chemicals Data Information Network gives a flash point of 25 C for the same
 liquid (see : http://ulisse.etoit.eudra.org/Ecdin/Ecdin.html).
 
 Janice Baker said earlier that ABZOL from Albemarle is also n-propyl
 bromide.  But Albemarle state that their ABZOL cleaners have no flash point
 ! (see : http://www.albemarle.com/abzol.htm).
  >>

First of all the values given (21 & 25 oC) are essentially the same, and both
wrong. If
you don't run the test right, you can make n-PB flash. That's why the 21 &
25 oC values exist from older literature. If the test is run right, the
bromine atom suppressor quenches the natural tendency to flash of a C3
hydrocarbon (it fools the test). Three mechanisms speculated are: (1) the
heavier halogen forms a barrier to oxygen reaching the liquid, so the
mixture is too lean to support conbusion; (2) the bromine atom scarfs up
electrons present in any combustion reaction with oxygen; and (3) if the
initial test temperature  chosen is too high, you miss the real combustion
temperature [around -20 oC] and run the mixture too rich (and this happens
frequently since few bother to use liquid Nitrogen to cool the mixture to
this level and carefully babysit it as it warms).   I believe that both
Albemarle and GLCC
contracted with  independent labs to support their own no-flash data, and
the labs validated their results  = in the ASTM closed cup test, it
doesn't flash. That means it isn't "hazardous," has no flash point, and "is
not flammable."

Second, you can make it catch fire. It will burn with oxygen in geometries
different than those in the ASTM closed cup test. n-PB has a UEL & a LEL.
The difference is the geometry of the test equipment.

Third, the Internationl DOT says if a product does not have a UEL / LEL, it
is not flammable; the US DOT says if a product does not have a flash point,
it is not flammable. Albemarle chose the US DOT approach; I think that
initially GLCC may have taken the International DOT approach, but have since
changed to the US DOT approach since they do produce and sell chiefly
domestically.  Albemarle produces overseas, so I'm not sure how that shakes
out for them corporately.

The best one-sentence answer is that it is just like 1,1,1 TCA in its flash
point behavior.

Hope this helps!

Janice Baker