need to find a replacement K type probe for this thermometer

[Jim Horton]

I have had this thermometer for probably a decade. About three years
ago, I accidentally put the K type probe into something too hot and
ruined it. Now it's time to get another probe, but I'm not sure which
one. I lost the info on the thermometer, but here is an image:

https://i.imgur.com/RHXsSsS.jpg

Suggestions for both a manual and replacement probe would be welcome.
Thanks in advance.

[Jim Horton]

Please note that I know it needs a new K type probe, but I don't want to
end up overspending on a high temperature one if the meter won't range
that high, but I can't find the meter specs online since I lost the
manual.

[Ralph Mowery]

In article <qpcp43$v1t$1...@dont-email.me>, jho...@nospam.net says...

All thermo coupler probes of the same leter are the same. There are
several different letters used.

Just find any K type that the plug matches the instrument you are using.
The plug should be made out of the same material as the t/c.


The most common plugs are usually the K and J type. They will not
interchange and give the correct temperature.

You must have really stuck it into something hot. The K type is good
for around 2000 deg F. You could have melted the probe if it was some
sort of plastic, but the T/C should still be good unless it was over
about 2000 deg F.

[Ralph Mowery]

In article <qpcpjn$v1t$2...@dont-email.me>, jho...@nospam.net says...

>
> Please note that I know it needs a new K type probe, but I don't want to
> end up overspending on a high temperature one if the meter won't range
> that high, but I can't find the meter specs online since I lost the
> manual.
>
>
>

A thermocouple probe will range for whatever the letter of the probe is.

That is any K probe will work with any K meter. It does not matter what
the display part of the meter is rated for. A TC probe is made of two
types of metal and that only depends on what letter the meter part is
made for.

You may pay more for the probe depending on the insulating material of
the wires.

That seems to be an inexpensive meter and you can probably buy a new one
similar to it off ebay for what the probe will cost you.
There seems to be many like it with a few extra buttons.

[Phil Allison]

Jim Horton wrote:

------------------

** Did you do any Googling at all?

K type probes and wire tipped versions are all compatible with the same meters.

https://store.wirelesstag.net/products/thermocouple

I like the tipped ones cos thermal inertia is so much smaller - means I can measure power semiconductor case temps in a few seconds.



..... Phil

[Jim Horton]

Thanks. Yes, I did Google it but the uncertainty was the range of my
meter and whether or not it made any difference. Doesn't appear to, so
I will be ordering a replacement probe shortly.

>
>
>
> ..... Phil
>

[Phil Allison]

Jim Horton wrote:

------------------

> Phil Allison wrote:
>
> > ------------------
> >
> > ** Did you do any Googling at all?
> >
> > K type probes and wire tipped versions are all compatible with
>> the same meters.
> >
> > https://store.wirelesstag.net/products/thermocouple
> >
> > I like the tipped ones cos thermal inertia is so much smaller
> > - means I can measure power semiconductor case temps in a few seconds.
>
>
> Thanks. Yes, I did Google it

** Now, you need tell us that in your first post.

> but the uncertainty was the range of my
> meter and whether or not it made any difference.

** What did you actually Google for?

Cos I found this in about 30 seconds:

http://www.tes.com.tw/en/product_detail.asp?seq=324

> Doesn't appear to, so I will be ordering a replacement probe shortly.
>

** So, it is a probe or wire tipped item you are after?

Most stand alone meters, like yours, cover the full range of a K-type thermocouple.

But probes and wire tipped jobs have upper temp limits due to the insulation used in making them.

If we don't know what you are doing - how can we possibly help you ?



.... Phil

[Jeff Liebermann]

On Wed, 30 Oct 2019 15:42:59 -0400, Jim Horton <jho...@nospam.net>
wrote:

About half of my various digital multimeters can be used as a
thermometer using a Type-K thermocouple probe. Perhaps it's time to
junk your 10 year old meter and just use a multimeter? Or, perhaps
add some additional functionality, such as a data logger?

I can't deduce what style of Type-K probe you managed to destroy. So,
pick a photo that looks familiar as any Type-K probe will work.
<https://www.google.com/search?q=k-type+thermocouple+probes&tbm=isch>
<https://www.ebay.com/sch/i.html?_nkw=type-K+thermocouple+probe>

I prefer the bare thermocouple end with the common yellow flat blade
type connector. For use on some instruments, I have an adapter to
banana plugs. The wire is usually fiberglass wrapped to handle the
heat. If I need a tip for better heat conduction or mechanical
attachment, I stuff the tip into a copper or brass tube, and fill with
whatever is handy. If I want accuracy, corrosion resistance, or high
temp, I use a commercial probe. For example, for a >1000C kiln:
<https://www.ebay.com/sch/i.html?_nkw=type+k+thermocouple+probe+kiln>
Or, use tape or glue:
<https://www.ecd.com/support/learning-center/resources/thermocouple-attachment-methods.aspx?Post=3916&tabid=371>

Hint: Perform a rough ice bath and boiling water sanity check on any
probe you buy. I've seen a few surprises and built a few defective
probes.

--
Jeff Liebermann je...@cruzio.com
150 Felker St #D http://www.LearnByDestroying.com
Santa Cruz CA 95060 http://802.11junk.com
Skype: JeffLiebermann AE6KS 831-336-2558

[Jeff Liebermann]

On Thu, 31 Oct 2019 08:59:20 -0700, Jeff Liebermann <je...@cruzio.com>
wrote:

>Or, use tape or glue:
><https://www.ecd.com/support/learning-center/resources/thermocouple-attachment-methods.aspx?Post=3916&tabid=371>

I just started using this glue for attaching thermocouples:
<https://supergluecorp.com/product/zap-it/>
About $8 for 4 oz. I can position the sensor, slop on some glue, hit
it with some UV light, and I'm done in a few seconds. Of course, the
bond is essentially permanent, so you have to do it right the first
time.

Also, you can make your own thermocouples with a specialized welder:
<https://www.amazon.com/TL-WELD-Thermocouple-Thermocouples-Temperature-90V-240V/dp/B01N280272>
with a 12v car battery and a hammer:
<https://pcbsmoke.wordpress.com/2015/08/27/makeshift-thermocouple-spot-weld/>
with almost any common heat welding method (oxy-acetylene, HHO
hydrogen torch, Brown gas, etc):
<https://www.google.com/search?q=hho+mini+torch>
or if you have some environmentally incorrect mercury available:
<https://www.practicalmachinist.com/vb/general-archive/thermocouple-wire-83495/#post130354>

[Fox's Mercantile]

On 10/31/19 11:32 AM, Jeff Liebermann wrote:
> Also, you can make your own thermocouples with a specialized welder:

Back at TRW I'd just use a suicide cord and a #2 pencil lead
as an arc welder to "weld" the two wires together.

--
"I am a river to my people."
Jeff-1.0
WA6FWi
http:foxsmercantile.com

[Ron D.]

A few things:
K is a common thermocouple
let's say if you wanted room temp or cryogenics then use T Type

Wire is made with limits of error. It's not great for knowing the traceable temperature. +-1 degree is common.

Probes are limited to your application. Some Kapton surface probe would be limited by the Kapton

What are you going to be measuring? Pipe clamp?

Readouts have another problem. I've had some that would start measuring at 250 degrees Centigrade. Not likely for your type of device.

Quick meter test. Short the inputs with a piece of copper wire, If the device is capable of measuring room temperature, it will read room temperature.

There is thermocouple wire and thermocouple extension wire. Don't confuse the two. You don't make junctions with extension wire.

Multiple parallel junctions average, Even when they are at the tip.

They are color coded. Yellow outer jacket is K. The inner conductors are colored too. RED is always negative for thermocouples in general, (at least in my experience). I've used R,S, J,K, T and C.

I'm familiar with mineature and full size connectors.

The junctions (or two 1/2 junctions) should be isothermal.

Old school was two thermocuples in series and one in an ice bath. Then use the tables (reference 0 C) to convert voltage to temperature.

New school. Use a precision semiconductor sensor an measure the temperature of the terminals. Do a reverse lookup and use that mV value. Add or subtract, then look value in a table or polynomial.

Thus the ability to ambient compensate is limited. The temperature where the meter is located.

[Jim Horton]

On 10/31/19 11:59 AM, Jeff Liebermann wrote:
>
>
> About half of my various digital multimeters can be used as a
> thermometer using a Type-K thermocouple probe. Perhaps it's time to
> junk your 10 year old meter and just use a multimeter? Or, perhaps
> add some additional functionality, such as a data logger?
>
> I can't deduce what style of Type-K probe you managed to destroy. So,
> pick a photo that looks familiar as any Type-K probe will work.
> <https://www.google.com/search?q=k-type+thermocouple+probes&tbm=isch>
> <https://www.ebay.com/sch/i.html?_nkw=type-K+thermocouple+probe>
>

I still have the actual K probe:

https://imgur.com/a/4H9rNrs

The probe, when plugged in, still shows temperatures but very
inaccurately. You can see what happened in the third image with parts
of the feed wire having insulation burned away. Perhaps it could be
repaired? Never thought I could, just assumed I ruined it. The
insulation looks like some form of Teflon or similar.

[Jim Horton]

On 10/31/19 1:47 PM, Ron D. wrote:
>
> A few things:
> K is a common thermocouple
> let's say if you wanted room temp or cryogenics then use T Type
>
> Wire is made with limits of error. It's not great for knowing the traceable temperature. +-1 degree is common.
>
> Probes are limited to your application. Some Kapton surface probe would be limited by the Kapton
>
> What are you going to be measuring? Pipe clamp?
>
> Readouts have another problem. I've had some that would start measuring at 250 degrees Centigrade. Not likely for your type of device.
>
> Quick meter test. Short the inputs with a piece of copper wire, If the device is capable of measuring room temperature, it will read room temperature.

Thanks for the info. I just posted pictures of the probe and damage in
my prior post. It does/did read room temperature. In fact, to my
surprise, with the probe plugged in right now, it is measuring within 7
degree F of actual room temperature. With the missing sections of
insulation, if I dip into any liquid, it throws the temperature way off.

[Jim Horton]

On 10/31/19 1:54 PM, Jim Horton wrote:

I just stuck the probe under my tongue. In the past when it was
working, it would read within +/-3 F of actual body temp, but today it
drops to read nearly 0 F.

[whit3rd]

On Thursday, October 31, 2019 at 10:47:41 AM UTC-7, Jim Horton wrote:

> I still have the actual K probe:
>
> https://imgur.com/a/4H9rNrs

Such a 'probe' is just a pair of dissimilar wires, insulated on the length, welded at the tip.
You can snip off the damaged bit, trim back the insulation, and re-weld a tip. Accuracy
wont be harmed unless the alloy of the probes is significantly changed.

[Jim Horton]

On 10/31/19 4:28 PM, whit3rd wrote:

>
> Such a 'probe' is just a pair of dissimilar wires, insulated on the length, welded at the tip.
> You can snip off the damaged bit, trim back the insulation, and re-weld a tip. Accuracy
> wont be harmed unless the alloy of the probes is significantly changed.
>

Solder or weld? I can do solder, but no welding capability here.
Thanks, though.

[Jim Horton]

On 10/31/19 4:28 PM, whit3rd wrote:

Ok, I clipped off enough that, when I now touch the wires together, I
get room temperature and body temp accuracy if I put the probe in my
mouth. I can see the two wires under a magnifying glass. I wonder if I
could use my "15 minute" oxygen/ propane torch to weld the tip?

[Ralph Mowery]

In article <qpf749$4fn$1...@dont-email.me>, jho...@nospam.net says...

>
> Thanks for the info. I just posted pictures of the probe and damage in
> my prior post. It does/did read room temperature. In fact, to my
> surprise, with the probe plugged in right now, it is measuring within 7
> degree F of actual room temperature. With the missing sections of
> insulation, if I dip into any liquid, it throws the temperature way off.
>
>
>

You can probably cut the wires back to where the insulation is not
melted and twist them together vrey tight and it will read the
temperature at that point. If you could weld, not solder the wires
together it should still work.

If you want to measure liquid temperture, the wires do have to be
isolated from the liquid. Any thing that conducts electricity between
the wires will cause a false reading.

It is probably showing the incorrect temperature in your mouth because
the liquid or skin resistance is causing a false voltage between the
wires without insulation.

[Ralph Mowery]

In article <qpfhqk$9qa$1...@dont-email.me>, jho...@nospam.net says...

> Solder or weld? I can do solder, but no welding capability here.
> Thanks, though.
>
>

They should be welded. Solder introduces another materal. The two
wires are different materials all the way back to the meter. Even the
plug should be made of the same material on each terminal. At the tip
they are joined together and form a junction that generates a voltage
depending on the temperature. I don't know if all metels do that or
not, but do know there are about half a dozen types of T/Cs that are
standard. Each one is designated a letter as to the material it is made
of.

Where I worked we used thousands of them. Mostly J type and some K
type. The company that made them for us was local and had a few spools
of the wire reserved for us so they would be consistant. Even with that
they could be off about 2 deg C at 300 deg C. from each other.

Part of my job was caliberating insturments that used them.

[Jeff Liebermann]

On Thu, 31 Oct 2019 12:07:01 -0500, Fox's Mercantile <jda...@att.net>
wrote:

>On 10/31/19 11:32 AM, Jeff Liebermann wrote:
>> Also, you can make your own thermocouples with a specialized welder:

>Back at TRW I'd just use a suicide cord and a #2 pencil lead
>as an arc welder to "weld" the two wires together.

You're dangerous. I like that. However, times have changed. You can
do far more damage these days with a $63 miniature inverter stick arc
welder:
<https://www.ebay.com/itm/HZXVOGEN-ARC-Welder-220V-MMA-Stick-ARC-Welder-IGBT-Inverter-ARC-Welding-Machine/143182473855>
"Cheap Ebay Welder -- WILL IT TIG?!"
<https://www.youtube.com/watch?v=--1lSmtuyUg>
Notice the 2 wire power cord.

I was looking for an excuse to buy a miniature brazing torch for the
small stuff, which might include thermocouples. The only problem is I
don't need too many thermocouples and I have a fairly good supply in
stock. Cheap enough to try without much financial damage if it can't
melt the nickel-chromium and nickel-alumel wires of 1400蚓 (2550蚌).
<https://www.ebay.com/itm/Jeweler-Jewelry-Micro-Mini-Gas-Little-Torch-Welding-Platinum-Metal-Soldering-Kit/273927011832>
A hydrogen torch should be able to generate up to about 2500蚓, so it
should work (hopefully without melting the tip).

[Jeff Liebermann]

On Thu, 31 Oct 2019 13:47:36 -0400, Jim Horton <jho...@nospam.net>
wrote:

>On 10/31/19 11:59 AM, Jeff Liebermann wrote:
>>
>>
>> About half of my various digital multimeters can be used as a
>> thermometer using a Type-K thermocouple probe. Perhaps it's time to
>> junk your 10 year old meter and just use a multimeter? Or, perhaps
>> add some additional functionality, such as a data logger?
>>
>> I can't deduce what style of Type-K probe you managed to destroy. So,
>> pick a photo that looks familiar as any Type-K probe will work.
>> <https://www.google.com/search?q=k-type+thermocouple+probes&tbm=isch>
>> <https://www.ebay.com/sch/i.html?_nkw=type-K+thermocouple+probe>
>>
>
>I still have the actual K probe:
>
>https://imgur.com/a/4H9rNrs
>
>The probe, when plugged in, still shows temperatures but very
>inaccurately.

The insulation appears to be shredded near the thermocouple. As
others have suggested, cut it back to where the insulation is still
intact, and weld the tip. That's weld, NOT braze, solder, glue,
crimp, sleeve, or twist. Just weld.

>You can see what happened in the third image with parts
>of the feed wire having insulation burned away.

I only see one image and one URL, but it's enough. The insulation is
gone. I'm not sure why you're getting "very inaccurate" readings. Are
the readings high, low, erratic, intermittent, or insane?

>Perhaps it could be repaired?

Yes, by welding. However, it would be prodent to spend a few dollars
and buy a new Type-K probe so that you can compare your repaired probe
with one that is more likely to be accurate.

>Never thought I could, just assumed I ruined it.

Nope. Note my domain name: LearnByDestroying.com. That means you
don't really understand how something works until after you've broken
it and subsequently repaired it.

>The insulation looks like some form of Teflon or similar.

The high temperature insulation can be PTFE (Teflon), PFA
(perfluoroalkoxy or Neoflon), XC, XS, XR, or XC4:
<https://www.omega.com/en-us/wire-and-cable/thermocouple-and-rtd-wire-and-cable/xc-xs-xt-xl-wire/p/XC-J-20-50>
<https://assets.omega.com/pdf/cable-and-wire/thermocouple-and-rtd-wire-and-cable/XC_XS_XT_XL_WIRE.pdf>
Chemically resistant wire uses FEP (fluorinated ethylene propylene)
insulation.

[Jim Horton]

On 10/31/19 6:05 PM, Ralph Mowery wrote:
>
>>
>
> You can probably cut the wires back to where the insulation is not
> melted and twist them together vrey tight and it will read the
> temperature at that point. If you could weld, not solder the wires
> together it should still work.
>
> If you want to measure liquid temperture, the wires do have to be
> isolated from the liquid. Any thing that conducts electricity between
> the wires will cause a false reading.
>
> It is probably showing the incorrect temperature in your mouth because
> the liquid or skin resistance is causing a false voltage between the
> wires without insulation.
>

Interesting, so even the welded wires still have to be insulated then.
As you say, the reason for the faulty readings I am getting.
Unfortunately, I don't have anything decent other than shrink tube and
leftover high temp RTV to coat them with, so I think it's time for a new
probe.

I will point out that the group has been a big help in informing me how
these work and my thanks.

[Phil Allison]

Jim Horton wrote:

-------------------------------

> I still have the actual K probe:
>
> https://imgur.com/a/4H9rNrs
>

** Does that look like a "probe" to you ?

Replacements cost about $5

WTF are you doing here ?

Wasting our time for your fun ?

> The probe, when plugged in, still shows temperatures but very
> inaccurately.

** Yeah, the insulation has failed and there are shorts in the cable.

Did you try to measure a flame ?


.... Phil

[Jim Horton]

On 11/1/19 6:46 PM, Phil Allison wrote:
> Jim Horton wrote:
>
> -------------------------------
>> I still have the actual K probe:
>>
>> https://imgur.com/a/4H9rNrs
>>
>
> ** Does that look like a "probe" to you ?
>
> Replacements cost about $5
>
> WTF are you doing here ?
>
> Wasting our time for your fun ?

No. Thermocouple. I stand corrected. The thermocouple isn't an
absolute necessity at the current time, but I miss having it working
correctly. It has been needing replacing for a couple of years and I
could have used it to measure wax temperatures recently. Instead I used
a cheap, wireless IR thermometer.

>
>> The probe, when plugged in, still shows temperatures but very
>> inaccurately.
>
>
> ** Yeah, the insulation has failed and there are shorts in the cable.
>
> Did you try to measure a flame ?

To be honest, I don't remember. Either a flame or I was experimenting
with solar cookers using fresnel lenses a few years back. These can
become quite hot with large lenses like I had (3000+ F), so chances are
concentrated solar energy hit the insulation and melted it. Not sure,
however.

>
>
> .... Phil
>