In my opinion, if your vapour degreaser does not have the features I
mentioned, then the best thing you can do with it is to find a scrap
metal merchant who will give you a good price for the SS! It would cost
more to adapt it (e.g. $15k-30k for a refrigerated freeboard, $5k-10k
for auto sliding doors, 20k-50k for a programmable hoist etc.) It would
be more economical to buy a new machine of modern design! I have seen
old VDs used as simple immersion tanks for non-volatile substances!
It may interest you to know that one of my tasks when working as a
consultant for the UNEP MLF was to check that old VDs, many with
inadequate freeboards, were destroyed beyond all possibility of re-use!
In one Chinese factory we visited, the "destruction" was one 3 mm hole
drilled into the bottom of each tank (obviously easy to argon-weld it
closed again). I considered this inadequate destruction and informed the
accompanying UN official. He immediately asked the owners for a
sledgehammer and he started knocking hell out of the whole machine - and
this was a guy who reported directly to the Secretary-General of the
MLF! I have a photo of him, in a beautifully tailored suit, doing this! :-)
You ask me what I would use in a VD. In the first place, the only VD I
would use today would be a fully closed zero-emissions type from $80k to
500k. I would not consider an open degreaser except a very few special
designs. Whatever I would use inside it would depend on what I was
doing. For most metal degreasing, I would use stabilised
trichloroethylene as my first choice (cheap, moderate toxicity, over 100
years of field records, safe, easily obtainable from multiple sources).
I would not use a VD for most defluxing: possible exception for some
hybrid designs as the hydrogen bonding of the flux to the substrate is
much weaker than with an organic substrate and some hybrids are attacked
by water-based cleaners. In this case, I would use a TCE-methanol
azeotrope, bearing in mind that the stabilisation of such mixtures is
hairy and requires careful maintenance. I would not use one of the
"designer" solvents, except as a last resort.
HCFC-225, as has been pointed out, is a no-no, although it closely
matches CFC-113 in most characteristics. The Vertrel HFCs and the 3-M
HFEs are not good solvents unless blended with trans-dichloroethylene
and alcohols, thus losing their advantages of good stability and low
toxicity; they are horrendous global warmers, from 300 to 1500 times
worse than CO2, besides being horribly expensive. Personally, I would
never use nPB with our current lack of knowledge.
I maintain the same position I have held for over 40 years: water is the
best defluxing solvent. Believe me, I was considered an iconoclast for
this belief which I published in the 1960s and was really detested by
the CFC-113 makers! :-)
Brian
Steve Gregory wrote:
> Hi Brian!
>
> I read everything at the link you provided, and I am giving it thought. Our degreaser doesn't have an extended freeboard, so that would need to be added if we were to go to Ensolv.
>
> Let me ask you this, what would you use in a vapor degreaser? I did a search on vapor degreasing chemicals and almost everything that I came up with were nPB based...what else can I use?
>
> -Steve Gregory-
>
> -----Original Message-----
> From: TechNet [mailto:[log in to unmask]] On Behalf Of Brian Ellis
> Sent: Monday, August 21, 2006 10:17 AM
> To: [log in to unmask]
> Subject: Re: [TN] Vapor Degreaser...
>
> I do not recommend EnSolv, as it contains nPB. You can learn a little about its environmental and H&S issues - and both require serious thought - at http://www.cypenv.org/worldenv/files/npb.htm.
>
> If you must use it in a vapour degreaser, the recommended practices to reduce emissions include a deep (1½ times the opening diagonal) refrigerated freeboard, automatic sliding doors, small baskets to prevent pistoning the vapour out of the machine, draught-free environment, automatic hoist to respect freeboard dwell times and prevent brusque movements, minimal disturbance when filling/emptying machine and only when cold etc. I would also recommend operators wear badges so that their exposure can be constantly monitored. Listen to the operators for any unusual symptoms. The operators should wear protective clothing, bearing in mind that dermal uptake of nPB can be significant.
>
> UNEP discourages the use of nPB wherever possible.
>
> Brian
>
> Steve Gregory wrote:
>> Good Mornining All!
>>
>> Just curious, are there any of you out there still using a vapor
>> degreaser? If so, what are you using in it?
>>
>> We have a Baron Blakeslee MLR-120 that looks in pretty good shape and
>> we're thinking about using it for certain cleaning applications. I've
>> been looking at some Enviro Tech Ensolv-Ionic solvent to use in it.
>>
>> There's been some suggestions to use alcohol in it, but I don't think
>> that's a very good idea considering the flammability of alcohol. But
>> besides that, alcohol isn't a very good solvent anyway.
>>
>> Just wondering if anybody is still vapor degreasing anymore...
>>
>> Thanks!
>>
>> -Steve Gregory-
>>
>>
>>
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