K Type OMEGA SMPW TT-K-30 SLE Thermocouple Quick Product Review (Year 2024)

[Kiriakos GR]

I am nowadays in to a fresh research this relative to K Type Thermocouple and the ones with greater compatibility at the applications of soldering de-soldering of electronic components.

This travel started by me starting to explore as first Thermocouple sensors for soldering iron tip.
And yesterday Ali-Express search engine, this directed me at product solutions of K Type Thermocouple, these used at BGA and rework stations.

OMEGA SMPW-TT-K-30-SLE  this is a complex part number,  its actually a very thin probe for Max of 250C, but due it thin design it can pass-thru metallic spiral tube (flexible tube), which is a thermocouple holder, attached to a machine.

Now lets break down the OMEGA long part code:

SMPW = The code of the yellow miniature plug alone, this is an advertised product design since 2009.
 
TT-K-30 = The code of the attached wire, this is in production since 2012, Insulation material PFA.

SLE =  Special limits of Error Wire / a special customer request for a different accuracy tolerance.


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It is very interesting that this assembled thermocouple come with three temperature specifications.

a) Bare wire measuring range =  -200C ... +260C

b) Wire insulation Max tolerance = 260C (Teflon (teflon) temperature range)

c) Plug usable temperature range = Minus 200℃ to 220℃   

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Long story in sort, I did discover the product code of  SMPW- GG-K-30 SLE,  this is the one which attracted my interest.
I have plenty of 250C max thermocouple in my stock,  no-name up to the ones offers one with their multimeter.

The bead shape thermocouple this capable for 482℃ this is something that I do not have yet. 

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This OMEGA SMPW-TT-K-30 SLE, this is a free gift from a local friend.
And soon I will run a few benchmarks, so to discover of how an American made probe measure up VS similar work of Taiwan,  and even of China. 

I did prepare a interesting pack of photographs for our readers.   

[Kiriakos GR]

It seemed as very weird to me, the fact that OMEGA does not openly advertise their thermocouple specifications.

Instead they simply mention compliance to IEC 60584-2:1993 and they also say Tolerance Class 1.0
The translation now is that TTK30 this is:

Nickel Chrome/Nickel Aluminium (NiCr/NiAl)  ....  -200 to +260 °C: ±1.5 °C or ±T x 0.004 

And so ....  My magical OMEGA Thermocouple this is just ±1.5 °C of tight tolerance 

But I guess that I am still lucky, Tolerance Class 2 = ±2.5 °C or ±T x 0.0075 (so this is the worst that it can get)

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OMEGA offers a wide variety of Special Limits of Error (SLE) Thermocouple wire.

So the additionally added error limit this getting down to ±1.1°C or 0.4%

https://sea.omega.com/tw/pptst/SLE_WIRE.html

[Kiriakos GR]

I did promise a mini review and here it is.
For some time I was collecting any technical information’s that OMEGA was providing so and I to better define of what is needed so to test properly this precision K Type thermocouple.

Since the moment that I did find that  (SLE) translates to lower Error tolerance 0f  ±1.1°C or 0.4%,  the closest equivalent this is no other than LM35 active temperature sensor.

LM35 this has operating range -50 up to 150C and ±0.5°C tolerance which is tighter one compared to OMEGA sensor.
 
LM35 = ±0.5°C
OMEGA = ±1.1°C

Back in time that I did make my LM35 based project, I was unaware that similar design it is also used by HIOKI Japan, as external sensor for the measurement of Thermocouple, Cold-Junction Compensation.
HIOKI DC Signal source SS7012 (portable calibrator), this has an option of external temperature probe, so the user to be able to measure environmental temperature, and to add this as Cold-Junction Compensation if the thermometer and or DUT this requires manual input of Cold-Junction Compensation.
GW Instek GDS-320 Oscilloscope + DMM, it does accept Cold-Junction Compensation.

An so here we are with a test bed including BM869 that supports T1 + T2 (dual K-type input), along of HIOKI DT4282 for mV DC measurement’s.

LM35 in this case it is used as precision temperature source and probe.
Output is 227.79 mv and or 22.779 Celsius
Omega K-type = 23.0C
Brymen K-type = 23.3C

The test bed stayed 10 minutes without of me touching anything prior taking the photographs, which is enough time for temperature stabilization.

The obvious conclusion, the OMEGA thermocouple appears to include a tiny amount of error, compared to LM35, of +0.2C while the BRYMEN (Taiwan) thermocouple this is +0.5C as higher.

But there is also one detail this not be in any book, that a thermocouple without permanent installation this add also measurement error.
Even this two K-type thermocouple, these hold by a tiny clamp with half square centimeter of pad together, they are not at identical sensing position.

Now I get it, no one will bother to inspect thermocouple calibration lower than single Celsius degree as difference.
Two degree of error this might be an issue at food industry R&D, but in electronics over 5 Celsius of difference this might be an issue.

Too many lessons learned at a single testing session for me again.
I hope this to be also interesting as food for thoughts to you. 

Note: BM869 T1 T2 calibration were inspected, both inputs deliver identical measurement. 

[overvolt]

Excellent food for thoughts.

It is also expected from 100C ~ 260C any tolerance error, to be more obvious.
And for high temperature K-type at 480C, by far more obvious.


Interesting find the information about HIOKI temperature probe 9184 (For reference contact compensation).