Looking 4...

From: pete_at_dunnington.u-net.com <(pete_at_dunnington.u-net.com)>
Date: Sat Jan 4 17:21:01 2003

On Jan 4, 12:36, Philip Pemberton wrote:
> pete_at_dunnington.u-net.com wrote:
> > MEK is indeed methyl ethyl ketone, aka butanone.
> Just out of interest, how does it compare with acetone?

Acetone: TLV 1000ppm
Butanone: TLV 200ppm
IPA: TLV 300ppm

BUT please note these figures vary from authority to authority because of
differing regulations in different countries, and are sometimes revised in
the light of research or experience. The figures I've given are from the
Chemical Society in the UK, and US values may differ. Also, TLV says
nothing about what the effects of excessive exposure might be, nor about
other hazards (fire, caustic effects, etc).

> > Like IPA, acetone (nail
> > varnish remover), methylated sprit, etc, it's fairly flammable.
> Er, fairly flammable? From the reports I've read, it's worse than petrol
> (unleaded, LRP, take your pick).

Actually it's somewhat harder to ignite than petrol, and harder than
acetone. Petrol contains a number of fractions some of which are more
volatile than MEK. From memory (because I don't have any figures handy)
about 5%-10% of petrol is a fraction with BP around 20C-30C, and about 25%
with BP in the range 30C-50C. Boiling Point of acetone is 56C, MEK is 80C.

Petrol is rated as "extremely flammable", as are diethyl ether and
petroleum ether; acetone, MEK, and IPA are all "highly flammable", as are
ethanol and methanol. And if you want the TLV, it's 500ppm (that's without
the nasty additives).

> > BTW, the acetic acid given off
> > by curing RTV is rated as 10-50 times more toxic than MEK :-)
> Hmm...

Acetic acid: TLV 10ppm

TLV (threshold limit value) is a time-weighted average concentration to
which a worker can be exposed day after day without adverse effect.

> I've just found a page that lists some solvents and their uses -
> http://www.seahawkpaints.com/solvents.html
> It lists Xylene as being usable for epoxy and polyurethane resin removal.
> Hmm... Shame the only source of xylene I have is the stuff mixed with
> varnish in my Electrolube "CPL" lacquer pen.

You can get it from some trade paint suppliers as it's used as a thinner
for some epoxy paints. And of course from any industrial or laboratory
chemical supplier, of which there are several in Yorkshire.

Pete						Peter Turnbull
						Network Manager
						University of York
Received on Sat Jan 04 2003 - 17:21:01 GMT

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