Thermowell Questions

[Mike W1]

Don't imagine anyone uses them in their lead pots but I've noticed references to them on here. Looked up and at a few of them mostly out of curiousity.

Do the TC probes friction fit inside the well or are they loose in there and the TC would then probably be reading air temperature in the well?

Doesn't seem like a bad idea to have if for nothing more than being able to remove the TC from a cold pot of lead. Saw a couple in the $5 range but the specs didn't give the inside diameter of the well.

Also would there be much temperature difference between reading the well temp instead of being immersed in the melt?

[Iron Whittler]

Id of thermo well is slightly larger than probe. It is usually threaded inside so thermo couple screws into it. It is vented a top to allow for expand and contraction of hot air inside. We used them on dryers and glass furnace. Usually no dif in temp. Probes lasted much longer because they were not exposed to the harsh operating environment.

[Mal Paso]

I don't think TCs work well unless they are immersed in the melt. Might be the low mass of the TC but "thermal drain" is a problem. TCs also have Stainless Steel jackets that don't conduct heat as well as the old school Copper jackets. Auber has some info. My first try I silver brazed the TC into the bottom of a Lee 4-20 with the tip even with the inside bottom. The reading was off 20 some degrees. Moving the tip in 3/8 inch so the bulb/tip was fully surrounded with melt fixed the problem and the unit (Auber} was accurate from room temp to 850F.

[bangerjim]

An inustrial sheathed t/c fits into an industrial well & is held in place generally by a spring-loaded nut assembly at the wire end. The spring pushes the tip (business end where the temp is measured ONLY) hard against the inside end of the well to insure intimate contact. The well also allows use in harsh environments AND......very important....replacing the t/c without shutting the process down, since it is heavy sealed (cast/turned from solid) 316SST construction generally.

The fit is a tolerance fit inside the well and the end is rounded to fit the rounded tip of the t/c, again insuring a complete intimate contact for as little as possible temp shift.

You do not need a t/c well in your little lead pot!

[Mike W1]

An inustrial sheathed t/c fits into an industrial well & is held in place generally by a spring-loaded nut assembly at the wire end. The spring pushes the tip (business end where the temp is measured ONLY) hard against the inside end of the well to insure intimate contact. The well also allows use in harsh environments AND......very important....replacing the t/c without shutting the process down, since it is heavy sealed (cast/turned from solid) 316SST construction generally.

The fit is a tolerance fit inside the well and the end is rounded to fit the rounded tip of the t/c, again insuring a complete intimate contact for as little as possible temp shift.

You do not need a t/c well in your little lead pot!

Thanks guys. Was just curious and wasn't planning on buying one!