Re: PCB Question

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Original poster: "Jason Petrou by way of Terry Fritz <twftesla-at-qwest-dot-net>" <jasonp-at-btinternet-dot-com>

>From the ammonia SG bloke...

This works for me...
Take a little oil from the tranny, and drop some onto a piece of fibreglass
wool. Place this at thoe bottom of a boiling tube, and somehow hold the tube
n its side. Then, place a few bits of broken pot about halfway down the
tube. (plant pot works perfectly). Put a stopper in the end and stick a
glass tube in the stopper so that any gasses goven off from the test tube
will pass thru the tube coming out of the test tube. Then get a bit of
rubber tube and jam it over the glass tube. Put this bit of tube in a basin
of water, then put a water filled test tube over it, so any gasses that come
out of the rubber tube will collect 'under water' in the second test tube.
Then, with the first test tubve still on its side strongly heat the bits of
broken pot from underneath with a blowtorch. The oil will evaporate from the
wool, and pass over the broken pot. The gas will collect in the second tube.
This gas is heavier than air so once you have collected a full tube be
careful not to 'pour out' the gas.

Next, put about 1 inch of weak bromine solution in the bottom of the tube.
If you cant get bromine, iodine will work but it must be warmed to about 50
degrees C before you put it in the tube. (also needless to say if the
halogen in the PCB oil is iodine then nothing will happen) Stick a stopper
in that tube and shake HARD. After about a minute the solution will change
colour - there are 2 possibilities:

1) The solution in the tube goes clear. This shows that you have a non-pcb
oil. The oil molecules are 'cracked' by the broken pot (which is a catalyst)
into a liquid hydrocarbon (which collects on the surface of the water) and a
gas called ethene. The ethene will react with the bromine to produce
1,1dibromoethene or 1,2dibromoethene, both of which are colourless.

2) The solution will not change, or only partially changes. The halogen in
the PCB oil has already reacted with the ethene to produce 1,1 or 1,2
di(halogen)ethene. Therefore if the reaction has already taken place, you
cannot react any bromine with it, because it has already all reacted. If the
solution turns slightly more clear, then it is just reaction with the excess
ethene.

I hope this helps - It seems to work IMHO. Here in the UK you can pay (not
too much) to have PCB oils removed from trannys without being fined. I have
used this method and if there are any biggggg chemical booboos i have made
please let me know.

The process above with the pot is called cat cracking or catalyst cracking
and is used to break long chain hydrocarbons into shorter ones.

Have fun!!!

Jason
P.s. I tried the ammonia gap with an old adjustable glass xray tube. It
works fine, until it starts to get hot. I noticed that the electrodes did
not burn though as the were tungsten. Then the whole thing promptly
exploded... so much for me bringing it ti Corby!!! moral is thicked glass,
slightly less ammonia (0.8atm instead of 1) and some kind of cooling. later
all...