[SS2S-Main] Re: Tempilstick

  • From: "Lampe, Mattias" <mattias.lampe@xxxxxxxxxxx>
  • To: "sugarshot@xxxxxxxxxxxxx" <sugarshot@xxxxxxxxxxxxx>
  • Date: Wed, 26 Nov 2014 09:58:12 +0800

Hi all,



although I can only contribute questions and not too many answers, here’s 
what’s on my mind:



1.       Wouldn’t both solutions (IR thermometer and thermocouple on surface) 
measure the flame temperature rather than the surface temperature of the 
material? After all, the flame also emits IR (depending on the gas being used.) 
Regardless of the temperature at which ablation starts, I suppose the 
thermocouples must be able to withstand the flame temperature.

2.       Do I understand correctly, that in order to determine the emissivity 
of the surface you’d need a “calibration run” with IR and thermocouples? Is 
emissivity temperature dependent? Hopefully not, so I suppose the calibration 
could be done at a lower (non-destructive) temperature!?

3.       Partially answering my previous question: When the material gets very 
hot and charred, it will probably change its emissivity. Some of the materials 
are nearly white, but will probably turn black when the binder undergoes 
pyrolysis. I’d guess it’s very likely that this also changes IR emissivity!?

4.       For “normal” materials (non-transparent), what’s the typical range of 
emissivity? How much error would it introduce into the temperature measurement 
to just assume a reasonable fixed value?

5.       Pt-100 sensors had also come to my mind, but I’d assume they require 
more complex analog circuitry to interface them to a computer and get accurate 
results. Am I right?



It almost seems that the method for measurement of surface temperature is a 
valid research topic in its own right ;-)



Have a good day!



Mattias



From: sugarshot-bounce@xxxxxxxxxxxxx [mailto:sugarshot-bounce@xxxxxxxxxxxxx] On 
Behalf Of Hans Olaf Toft
Sent: Wednesday, November 26, 2014 4:00 AM
To: sugarshot@xxxxxxxxxxxxx
Subject: [SS2S-Main] Re: Tempilstick



Ablation is likely to happen in the 400-600 C range, but the unit should be 
able to measure higher temperatures just in case. Getting the emissivity right 
may require a few experiments (and thermocouples). Warning: the cheap IR 
thermometers may have a fixed emissivity setting.
Hans

On 11/25/2014 08:34 PM, Brian Su (Redacted sender 
cycloniterulez@xxxxxxxxx<mailto:cycloniterulez@xxxxxxxxx> for DMARC) wrote:

From my very limited experience with IR thermometers, they're only accurate 
when correctly compensated for the emissivity of the surface being measured. On 
top of that, the cheap units can't measure above 900 degrees Celsius.



Kind Regards,



Brian Su.





Sent from my iPhone.


On 25 Nov 2014, at 18:26, Vicente Alvero Zambrano 
<vicente_alvero_14@xxxxxxxxxxx<mailto:vicente_alvero_14@xxxxxxxxxxx>> wrote:

Exactly. We need a continuously record the temperature. Therefore, the two 
proposed options, the pencil and the thermocouple are not suitable for our 
purpose. We will use several thermocouples within the cone, temperature 
recording. But abroad, will be in direct contact with the flame. That is why, 
we want to use an infrared thermometer. Does anyone know how we can do one and 
connect it to the computer?

  _____

Date: Tue, 25 Nov 2014 18:32:57 +0100
From: hot@xxxxxxxxxxxxx<mailto:hot@xxxxxxxxxxxxx>
To: sugarshot@xxxxxxxxxxxxx<mailto:sugarshot@xxxxxxxxxxxxx>
Subject: [SS2S-Main] Re: Tempilstick

Thermocouples are cheap and work well, but if they are embedded in a sample 
that gets torched, they will at best record the surface temperature of the 
sample at the brief moment they are at the surface. It may work - and even 
provide usefull data - but an IR thermometer will read the surface temperature 
continuously.
Hans
On 11/25/2014 05:34 PM, Brian Su (Redacted sender 
cycloniterulez@xxxxxxxxx<mailto:cycloniterulez@xxxxxxxxx> for DMARC) wrote:

This one sure looks much better.

Kind Regards,



Brian Su.





Sent from my iPhone.


On 25 Nov 2014, at 16:27, Grant Saviers 
<grants2@xxxxxxxxxxx<mailto:grants2@xxxxxxxxxxx>> wrote:

Here is another ebay seller with all thermocouple options, packaging 
variations, temperature compensated junctions, and EMI filtering, etc.  Looks 
to be professional grade engineering:

http://www.ebay.com/itm/Quad-Channel-K-Type-Thermocouple-Amplifier-Conditioner-Analog-Output-AD8495-/331032888967?pt=LH_DefaultDomain_0&hash=item4d13190687

On 11/25/2014 8:10 AM, Grant Saviers wrote:

A type K thermocouple is good to 1250 C.  It will need a simple instrumentation 
amplifier to get the signal voltage to a range compatible with the Arduino A/D 
converter.  For about $10 in parts you can build your own IN-AMP.  There are 
several choices for single chip IN-AMPs that will do the job and here is a 
board from China for $10, and the chip output is 10mv/deg C.

http://www.ebay.com/itm/AD597-Ultimaker-Temperature-Control-Board-K-Thermocouple-Signal-Amplifier-/321597894984?pt=LH_DefaultDomain_0&hash=item4ae0ba7148

Grant

On 11/25/2014 1:12 AM, flint hapirat (Redacted sender 
flinthapirat@xxxxxxxxx<mailto:flinthapirat@xxxxxxxxx> for DMARC) wrote:

One comment - The tempilstick temperature pens are rated between 38c-1093c...

Hope this is still helpful.




  _____


From: Vicente Alvero Zambrano 
<vicente_alvero_14@xxxxxxxxxxx><mailto:vicente_alvero_14@xxxxxxxxxxx>
To: "sugarshot@xxxxxxxxxxxxx"<mailto:sugarshot@xxxxxxxxxxxxx> 
<sugarshot@xxxxxxxxxxxxx><mailto:sugarshot@xxxxxxxxxxxxx>
Sent: Sunday, November 16, 2014 9:10 PM
Subject: [SS2S-Main] Re: volunteering



Thanks for your reply Markus,



It is a good idea. The main problem I see is that we need to measure high 
temperatures. I do not know exactly how much, but around 1200ºC. And this only 
measures halfway. Do you know if there is a sensor for arduino with this 
possibility?






  _____


From: m.bindhammer@xxxxxxxxxxx<mailto:m.bindhammer@xxxxxxxxxxx>
To: sugarshot@xxxxxxxxxxxxx<mailto:sugarshot@xxxxxxxxxxxxx>
Subject: [SS2S-Main] Re: volunteering
Date: Sun, 16 Nov 2014 23:21:22 +0800


Hi Vicente,

It is quite easy to build a data logger with an Arduino based micro controller, 
SD card, SD card socket, HEF 4050 voltage level shifter, DS1307 RTC and one (or 
more) MLX90614 IR thermometer(s) which communicate(s) over the I2C bus as well.
I am just doing this for a medical project.

Markus


  _____


From: vicente_alvero_14@xxxxxxxxxxx<mailto:vicente_alvero_14@xxxxxxxxxxx>
To: sugarshot@xxxxxxxxxxxxx<mailto:sugarshot@xxxxxxxxxxxxx>
Subject: [SS2S-Main] volunteering
Date: Sat, 15 Nov 2014 19:21:26 +0100

Hi all again,

Although a long time do not talk about it, yet we continue the investigation of 
ablative materials.

For the study of the material that will coat the nosecone of our rocket; 
Richard, Mattias and I already started last summer to work on it.



Throughout this week, I've been talking to Hans, and he thought the possibility 
to also measure the temperature on the side of the wall that is in contact with 
the flame. Would be measured by an infrared thermometer.



I am contacting you to see if anyone is interested, or know how, to attach an 
infrared thermometer with data logger that Liam is manufacturing for 
thermocouples.



By this, we can obtain pairs of temperatures at the same point. Both outside 
and inside of the wall, in order to obtain among other data, values of thermal 
conductivity and heat capacity of each material.



Thanks in advance for your cooperation and interest.











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