What is the best thermocouple?

[paulallen]

If I were to add a thermocouple to my roaster what is the best kind.

There are type K, type J, type T, etc.

Also Grounded tip, exposed tip, etc...

I'm going to connect it to a PID that I picked up.  It can be set to accept pretty much any thermocouple.

thanks

[Tex]

For this range of temps the type K t/c works best. If you're using a probe t/c then you'll want an exposed tip for faster response times. I prefer to use a beaded-end t/c - they're cheaper.

I buy thermocouples from Omega.

[paulallen]

For this range of temps the type K t/c works best. If you're using a probe t/c then you'll want an exposed tip for faster response times. I prefer to use a beaded-end t/c - they're cheaper.

I buy thermocouples from Omega.

I know exposed tip thermocouples have a quicker response, but I'm afraid of build-up and/or damage to the probe with one.   What percentage of coffee roasters use exposed thermocouples? 

Next question is do PID's account for the response time of the thermocouple?  Assuming I'm using an grounded thermocouple and a PID.

[J.Jirehs Roaster]

I have something like this in my SC/TO and the tip has not failed  for years..

[paulallen]

Is that an exposed probe or a grounded probe?  Can you see the weld of the wires?

[J.Jirehs Roaster]

not exposed..   there is only two wires to connect...  I don't know if its grounded or not..

[Tex]

I have something like this in my SC/TO and the tip has not failed  for years..

I buy these in packages of 5 for $39, and I use them in my SCTO. I'm still using t/c #1, but if it ever fails I've got 4 more on standby.

[paulallen]

I have something like this in my SC/TO and the tip has not failed  for years..

I buy these in packages of 5 for $39, and I use them in my SCTO. I'm still using t/c #1, but if it ever fails I've got 4 more on standby.

What are they, the link is bad.

[Tex]

I have something like this in my SC/TO and the tip has not failed  for years..

I buy these in packages of 5 for $39, and I use them in my SCTO. I'm still using t/c #1, but if it ever fails I've got 4 more on standby.

What are they, the link is bad.

They're beaded/welded 20 AWG with bare leads that would work with PIDs. The ones with miniature connectors are 5TC-GG-K-20-36-SMP-M would work with digital thermometers.

[paulallen]

Those probably won't work in a drum roaster (hottop, etc), how would you keep the probe in the same position.  Good idea though.

[Ascholten]

Wow at work I got literally thousands of feet of this stuff, twin pair, in insulation, thick / thin, high temp, you name it.  We generally use K for our furnace bed temps.  When a run gets damaged or whatever, I throw hundreds of feet away sometimes and put new in.....

Aaron

[jimec3]

Those probably won't work in a drum roaster (hottop, etc), how would you keep the probe in the same position.  Good idea though.

I use that kind in my hottop. I ran it through a thin piece of tubing that is mounted on the back wall of the roaster. If I need to change the TC I just feed a new one through the tube.