Cleaning RK05 packs (Was: LGP-30 Memory Drum Update)

Chuck Guzis cclist at
Fri Jan 6 00:44:44 CST 2017

On 01/05/2017 05:13 PM, allison wrote:
>> Freon TF works well on everything.  Too bad it's not available.
>> Is it still used for aircraft electronics?
> No its been obsoleted.  There are many other similar but not
> fluorinated hydrocarbons that are preferred and also good old soap
> and water.

No, it's been banned.  "Obsoleted" to me carries the implication that
there's something better.  TF was banned under the Montreal Protocol not
for its toxicity, but for the ozone-depletion characteristic of the
stuff when it was released into the atmosphere.  Same goes for most
chlorinated refrigerants.

HCFC-225 had been an adequate substitute, but that was phased out in
2015.  Too bad--it was almost as good as a cleaner.

Techspray (and NASA and a bunch of other outfits) have proposed some
possible alternatives;

If these were my packs, I'd drop them a line and see what they recommend
for the specific application.

FWIW, I buy my denatured ethanol from the paint store--it's about as
water-free as it's possible to get, usually with some methanol commonly
added as a denaturing agent, although other substances can be used.
This was a practice started in 1906 so that manufacturers could be
exempted from alcohol taxation.

During Prohibition, the government, responding to a higher moral
standard, reformulated the denaturing agents, making them even more
lethal.  The result was dramatic--in 1928, 700 people died in New York
alone from consumption of industrial alcohol.  Oddly, the 18th amendment
only forbade manufacture, sale and transportation of alcohol.
Consumption was still perfectly legal.

Paint-store alcohol is free of water because it's commonly used as a
shellac solvent/carrier.  Any appreciable amount of water results in a
cloudy finish.


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