This particular thermowell is 4" long with a 1/4" NPT threaded bushing. The threads face in the same direction as the sealed tube. The tube's ID accepts probes up to 1/4" in diameter.
Thermowells are devices that install into your vessels (or within your threaded plumbing) that allow a thermometer, digital thermometer probe, or temperature controller sensor to be inserted but kept isolated from the liquid the thermowell is immersed in.
We've sold hundreds of the probe compression fittings for doing a similar thing, but several customers asked us for a version that would allow the removal of the probe without losing the liquid in the vessel. This is also important if you're using a temp probe that is not already waterproof or made of food grade materials. You can get these in either 1/4" or 1/2" NPT, to support probe sizes up to 3/16" OD or up to 1/4" OD and all combinations are available to install weldlessly.
How do these differ from other thermowells" For one thing, they're less expensive because we shaved down the threaded fitting end to use less material. All the traditional thermowells have female threads on the insertion end assuming the use of a bimetal thermometer. Our thermowells are designed for thermometers, probes, etc.. that do not have threads on them.
Also, while this isn't a critical design feature, our NPT threads are machined a bit undersized so they thread all the way in to female fittings such as a tee for a more compact look. Because of this, you can either use teflon tape to seal the threads to a female fitting or you can use a gasket or oring instead. This makes it very easy to turn these into weldless assemblies without extra bulkheads (more on this below). These are all constructed of 304 stainless steel. The well tubing is thin wall for better heat transfer, has a smooth rounded closure at one end and is laser welded to the fitting on the other end. The well tubing also protrudes out of the hex side by about 1/4 inch.
As explained above, the larger well tubing (designated in the model number with an "L") will accept up to a 1/4" OD probe which is very common with temp controllers such as the Johnson Controls A419 series or the similar Ranco ETC-111 series as well as the ST1000 controllers. (we're not endorsing either of them, just using as examples). These units usually include a 1/4" OD probe with a stainless sleeve, but it's not long enough to insert into any vessel on its own. The large sleeve wells are available with either 1/2" NPT or 1/4" NPT threads as shown on the top of the picture to the left.
The smaller well tubing (designated in the model number with an "S") is 1/4" OD and will accept probes up to 3/16" OD. This size is best used for narrow probes found on the popular DTQ450, DTTC, Thermapen, and any other kitchen style digital thermometer. The smaller sleeve units are also available with either 1/2" or 1/4" NPT threads.
NEW Reversed-Bushing Version! Several customers asked
if we could flip the bushing around on the tube so that these could
thread into a welded coupling from the inside of the vessel for less
thread exposure. This would be important on cold-side operations such as
fermenters especially and it would also be easier to clean in the case
of mash tuns as well. Note, this design also works nicely with the "make
weldless" parts available as accessories. The only thing on the inside of your vessel will
be the tube, the hex of the bushing, and the gasket. We've also
recently made 10" and 18" long versions of these to be used in your tall
fermenters such as conicals and the SS BrewBucket. Don't forget, if you
want to install them in the lid of your fermenters, you'll want to add
the thermowell make weldless parts below (the thermowells do not include
Decoding the model numbers, cuz there are so many of them, and it's confusing.... ;-)
TW (length in inches) - (tube size "S" or "L") - (threaded bushing thread size 1/2" or 1/4" NPT) - (R = Reversed bushing)
The last units we have is a bare tube sleeves. They sealed in the same
way as the others on one end and is open on the other. The primary
application for this unit is to retrofit any of the previous probe
compression fittings you purchase or have purchased from us. You can buy
this if you have some custom design idea but don't have way to seal the
end. The model numbers are more simple and do not follow the formula above.