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Topic: For you scientific types (5 msgs / 119 lines)
1) From: Ken B
Does anyone know what the shielding on the thermocouple wires is made 
out of?
I ask, because I note that the shielding on mine is starting to fray a 
bit.  I do somewhere around 7-15 roast cycles a week in the IR-2, and 
have had this thermocouple in since I bought the machine a few months 
ago.  It is starting to look a bit frayed around the edges below the 
temperature point and where the top fits over it..  Maybe I am just 
paranoid, but can someone please confirm it is NOT made from asbestos?  
The IR-2 forces hot air over it and if it is asbestos and is fraying, 
this would definitely NOT be a good thing! Airborne asbestos is very 
bad, hokay?
If someone is knowledgeable on this, it would ease my mind if you spoke up.
Thanks,
Ken B
PS...if ya'll have not tried the El Salvador Matalapa Estate, you might 
wish to do so.  Personally, I think this is wonderful coffee, with nice 
hints of Praline in it. (FC- to FC)  Very balanced, sort of dry at 
first, but diminishes as the cup cools.  WONDERFUL stuff!
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2) From: Aaron
If it is the yellow / orange-red looking plastic type it's most likely 
nylon or teflon and shouldn't be a big deal.  If its the cloth type it's 
hard to tell.  Fiberglass is in some, 'angel hair' another type of 
'glass' type of insulation in others, and yet some had asbestos in them 
though I doubt you got one of those....  the asbestos ones IF they make 
them anymore are generally more industrial specific ones, made for power 
plants for furnace bed temps and the likes.  doubt your little pokey 
probe is one of them.... its probably a fiberglassish type of insulation 
and probably not too much of a health risk.
Get some high temp sealant like the silicone stuff thats good to 600 
degrees and gunk it all up to cover it, stop the frizzies and won't hurt 
you either.
aaron
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3) From: Rich
Dependant on the temp rating.  The thermocouple is good from close to 
absolute zero to melt.  The insulation determines the temperature 
rating.  Look on one of the manufactures web sites for thermocouples and 
they describe the insulation characteristics.
Ken B wrote:
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4) From: raymanowen
The low temperature thermocouples supplied with the meters have red and
yellow fiberglass braid insulating the negative (magnetic) and positive
(non-magnetic) wires.  Red is the magnetic and negative lead in a type K
thermocouple.
The red and yellow wires are in a second braided fiberglass insulation
layer.
You must be careful not to abrade the fiberglass. It's mechanically tender
and surprisingly easy to compromise, especially if it passes through a hole
in sheet metal. The sharp edge cuts right through the insulation and shorts
to the wires. That's your new junction, accurately measuring the temperature
of the sheet metal where it touches the wires. It will be intermittent too.
If you want shielding, you want a tungsten thermowell or at least a
stainless steel or Inconel sheath.
If you want a reliable installation, there's more to it than just stringing
up wires like Christmas lights. Running the s/s or Inconel sheathed probes
through a hole in sheet metal is begging for trouble, you'll just have
forgotten why, when it finally Gotcha!
Cheers, Mabuhay -RayO, aka Opa!
Einstein had a comment about doing things the same old way and expecting
different results.
On Fri, Mar 21, 2008 at 4:04 PM, Ken B  wrote:
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5) From: Ken B
Thanks to Aaron, Rich and Raymond for the replies. 
I did not think that anyone would still use asbestos in products for the 
consumer, but one would think they would not still use lead in paint 
either. :-) Sometimes it is better to ask.
Best Regards,
Ken B
Aaron wrote:
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