DIY Thermowell

[jas0420]

Hi all, I am in the process of making some stainless temp probes with DS18B20 sensors, the 1/4" stainless thermowells from Brewer's Hardware, and some Ethernet cable as suggested by Dallas.

I found that 5mm OD Ethernet cable fits like a glove inside these thermowells, and was pretty happy about that because some will be quite long and the rigidity will be good to make sure the probe makes it all the way to the base.

Several of these are going to be exposed to boiling or near boiling temps though, so now I am second guessing Ethernet cable (at least inside the t-well) due to the temps as that appears to be way outside of spec. Was wondering what temp-safe wiring others are using. ?? Gonna be a boat load of soldering and I definitely don't want to just have the wire coating melt away and short out on the first use!

Second question. I mentioned long thermowells... I am going to be dropping a temp sensor into the tops of my plastic conical a that need to be about 3ft long. I have some 1/4" stainless tubing and have not dreamt up a way to seal the ends. Not a fan of JB Weld touching my brew. I was thinking originally that I would try to blob up some silver solder to plug the end, but I am starting to be honest with myself that this idea is going to just end in frustration. (Haven't tried it yet though.). Any other ideas?

Thanks!
Jason

 

[BigBlock]

I'd try silver soldering(4% low temp) one of these in the end of the tubing

http://www.ebay.com/itm/311128867058?ssPageName=STRK:MESINDXX:IT&_trksid=p3984.m1436.l2649

 

[Bobby_M]

Find some stainless round bar that fits snug inside, cut a 1/4" long slug and silver solder it in place at the end of the tube. Grind/polish smooth..

 

[AnOldUR]

Find some stainless round bar that fits snug inside, cut a 1/4" long slug and silver solder it in place at the end of the tube. Grind/polish smooth..

Did this for a friend. He was using a 10 gallon corny for fermenting and wanted to put a probe down in the dip tube for temperature control. Plugged the end with a piece of stainless. Having a lathe to make it look pretty was a plus.

 

[jas0420]

Thanks for the replies! I was coming back to say that writing the original thread here must have jostled some brain cells because right after I wrote it I found THESE stainless caps on Grainger.

BigBlock, I love that idea, but if my math is right, those are the same diameter as my tubes so it would have to be an end-to-end joint. If that is possible with solder (I really need some stainless welding gear and skills), it is out of my skill set!

Round bar. Sigh. That caused a "why the heck didn't I think of that moment". That's perfect. Thank ya Bobby. AnOldUR, your work on that is beautiful. Very well done!

Anyone have thoughts on heat resistant wiring? I'm still going to use twisted pair on the probes like these long ones where there won't be high temps (and I need some rigidity to get the probe to the end). Think I'll go boil some Ethernet cable for an hour or so and see what happens.

Thanks guys!