Thermowells: HELP How to make cap/seal end ?

[roscoe]

I have some 6mm stainless pipe lying around and was thinking of having a go at making a few thermowells of various sizes.

How do you make a 'neat' job of capping one of the ends. The shop bought ones are ?spun and look hygienic, my first hammer-bash and solder is water tight but no oil painting.

Any suggestions from the gifted metal workers out there ?

[boingy]

I tapped the the first 5mm of the inside of the pipe, applied a tiny amount of JB Weld to it then screwed in a stainless machine screw and left it for a couple of days to set. Then I cut the excess screw off and filed and polished the end. It was a faff but made a neat job. You can barely see the join. If you have the means to solder/braze stainless then that would make an even neater job.

[Fil]

with copper tube i flattened a bit of tube in my vice jaws, sat it on the tube, and slodered it on using lead free plumbers solder and plumbers flux..

to solder SS use 4 or 8% silver solder and a liquid acid flux like harris stay brite in a needle tipped bottle for precision application..
thin tube and plate may be tricky with a gas gun but if u can get a big watt electric soldering iron it should be a doddle.. i picked up the tips and suitable material list from a us site and ended up importing US solder and flux via ebay as no one on the US site could recomend UK equivalents.. selection of solder with no toxic components and a flux which is washable off is crucial..

but its do-able - i did this 1st attempt...


its a 2" sanitary fitting with a 64mm flange on a 98l stockpot lid.

[roscoe]

Thanks, still looks like too much work for lazy me (and my poor metal working skills) ....

I'm now actually thinking of wiring up the DS18B20 and permanently fixing/embedding to just 1-2mm from the end with a spot/dod of JB weld then lightly attempt to smooth/polish. Ok, it would be better to be removable but.... at free to a zero/few quid for the SS pipe and £1 for the sensor I am happy to have a go at permanent. The cost of getting set solder/flux etc for SS also blows my meagre budget, I know recall I have some unused JB Weld.

Ok, I am looking to embed the sensor in the JB Weld rather have the DS18B20 immersed in the wort, but it was this guy that got me thinking this way...
https://forum.crystalfontz.com/showthre ... re-Sensors

Mad or stupidly clever,.... dunno

[Fil]

for making copper tube probes with naked basic component sensors check out this build

viewtopic.php?f=6&t=31341&hilit=brewery+computer

my plumbing soldering experience is very limited but i copied the probe idea and made copper thermowells, that gave me confidence to attempt a few more goes, and its easy if u 1) clean surfaces, 2) apply propper flux, 3) heat and apply not too much solder, AND USE LEAD FREE SOLDER...


tho ebay sellthe texas instrument probes built up with a lead and round ss sleeve for a pound or so each

if you can find a close fitting compression fitting, you can replace the olive with one or more silicone orings, i dont know the diameter of ebay probes, 4-5mm? I know this works very well for minor size differences such as using a 10mm compression fitting with a 3/8" tube..

Also teflon or ptfe is food/heatsafe, and with careful wrapping you bulk up a diameter with cheap plumbing tape, it takes patience or if u have a drill driver with variable speed u can spin it on very slowly, just make sure u get all rough edges off the tape reel rim as if snagged it will split and fray..
if u snag stop and remove the burr causing it and cut the fray out n start wrapping whole tape again, a pita but gives u a way to make a soft sealable wrap a few mm thick which when compressed in a compression fitting should seal with finger tightening.

i know lots of folk use jb-weld but its permanent,, and ive seen posts of pics of jb weld seals that have lost some colour with use n time,, tho i cant find one now to link to so internet fable warning

[Fil]

Or check out the ebay link in this post i just spotted..

viewtopic.php?f=6&t=62803&p=700077#p700077

[mojonojo]

Or check out the ebay link in this post i just spotted..

viewtopic.php?f=6&t=62803&p=700077#p700077

you mean this link - http://www.ebay.co.uk/itm/3m-Digital-Th ... 0699845438

[roscoe]

Great comments, thanks.

First off it's for top entry into a plastic fermentor, I don't want to go through the side and want 316ss so copper is out, also I want a long probe 20/22" /500mm is ideal. But generally I wanted to be able to knock it up myself without waiting for something to travel from the other side of the planet.

In the past I have bought these. Very good quality. Wish I new how to make off the ends, but 'spun shut and TIG sealed' is not in my toolbox!
https://www.oscsys.com/store/product/St ... obe-End-20

It's only 6mm dia of jbweld at the tip. I can live with that, could faff about and jam a small screw and file down to further minimise jbw exposed area, but that's ott for me. As long as I get a smooth polished finish on jbw I'd be happy. Some later 6mm spot discolouring I can live with.

Still open to more practical words of wisdom/inspiration.

[Fil]

assumption 1) vigorous fermentation will help mix the liquor in the fv to some degree, but cant be banked upon throughout the fermentation period as always going on and providing a mechanism for even temp distribution.

I ran some tests with still water in a SS FV with heat applied by a heat cable wrapped round the exterior. the temp change was gradual, and while no doubt some brownian motion was going on, the centre of the pot remained a few degrees cooler than the perimeter.

therfore i think its best to monitor the temp of the fv closer to where any temp change is being applied, so if in a fridge, and the temp change ocours via the air monitor the skin of the FV behind insulation, not the centre of the FV. application of + or - heat will ocour in smaller stages, the bulk temp will normalise, and if needed the change can be applied again, the result being a trend towards target temp in small steps for the whole bulk rather than overheating some of the liquor while the change in temp penetrates the bulk and reaches the probe, by which time the bulk could be over heated triggering cycling between heat and cold application...

So if you apply temp changes via a hex coil in the FV centre then yes i would measure the central temp a few inches away from the coil..

hope that makes sense, and is just my take on the situation, open for debate not gospel.. but without a pump or blade to mix the fv liqour to maintain an even temp throughout imho its better to apply change in small steps towards the tartget rather than risk overshooting and cycling.

[roscoe]

Fil, we're kinda drifting off topic, now
(I just want a cheap way of knocking up a thermowell from some pipe I have)

A conical fermenter using a top acting yeast with the ambient lower? during active fermentation is indeed acts as a 'natural' thermal mixer.

I can observe the central section has the largest thickest freshest krausen and you can actually see small nipple current effect of thermal current in the middle. Now what goes up (hot stuff) must come down and the cooler sides have a small downwards counter flow current. It is this very effect that leads commercial brewers to select the steepish conical angle and keeps the yeast (or is it beer circulating to the top yeast krausen party) up in the beer working most efficiently throughout the tank. Sorry can't quote the technical terms for these thermal currents, the same effect occurs in pots/tubs just not as well.

The points you are making maybe explained with a room heating radiator which happens to be a convector, where it's not a clever idea to locate the thermostat above/heat outlet or below/cold inlet, some other non-dead spot in the room is fine. The same practical logic works in the fermentor, so not close to the sides and not above/below any immersion coil if fitted to prevent cycling effect from a deadband on/off control. Of course, I presume if the ambient is much warmer the situation is slightly different but this doesn't normally apply for brewers in the UK? or not in my concrete based brick garage.

Then after the active fermentation ends the temperature will eventually equalise, however this depends on the height of the tank and time, the old fact heat rises comes to play here, but generally for an ale yeast its the top surface that presents the most interest in controlling or at least forming a repeatable understanding. For me with a decent US-05 fermenting away the internal beer is +2-3oC higher that the outside surface, a week later with no ferment its the same. My level of interest various greatly depending of the temperature tolerance of the yeast and I usually brew to suit the seasons until santas-sleigh drops of a chiller. If I had the means to measure surface and internal and trend, these would indicate clearly the fermentation situation. When I previous used pots in a fridge, the logged electricity trends of the fridge temperature control cycling would also clearly mark fermentation stages and vigour.

I don't really get the brownian motion comment, if I had temperature control it would be silicone heat pads/tape at the bottom cone section and an immersion coil dipped in the top half section. I now brew more than I can lift (which isn't much) so I usually try not use temperature control, but it is very handy to have to get out of jail, ie cock-up, sorry user error (me) or equipment/material malfunction, which thankfully is not that often.

The problem nowadays with many home brewers is that we've become all 'exotic' wanting brew all kindas of beers ticking off all manner of brews developed in different places. So instead of just sticking to the volume brand and the house yeast like the big boys do we 're doing all sorts at the wrong time of the year!