[SS2S-Main] Re: Tempilstick

  • From: Rick Maschek <rickmaschek@xxxxxxxxxxxxxx>
  • To: "sugarshot@xxxxxxxxxxxxx" <sugarshot@xxxxxxxxxxxxx>
  • Date: Wed, 26 Nov 2014 04:38:45 +0000 (UTC)

Hi Mattias,
I bought an IR 'gun' several years ago for measuring temp of the propellant. 
Since I didn't know the emissivity of the propellant, I measured the temps of 
several common materials of 'known' emissivity to compare with the readings of 
the propellant to since the IR gun has a preset .95 emissivity.
When used to attempt reading an aluminum motor case after firing the readings 
are always way low since the emissivity of aluminum is so low. And one of the 
things I've learned is the 'color' of a material does not necessarily give you 
an idea of a material's emissivity and it changes with some materials with 
temperature so as you say, it can be a study all of its own. 
Here's a site for some emissivity values: 
http://www.engineeringtoolbox.com/emissivity-coefficients-d_447.html 
Rick 

     On Tuesday, November 25, 2014 5:58 PM, "Lampe, Mattias" 
<mattias.lampe@xxxxxxxxxxx> wrote:
   

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{margin-bottom:0in;}#yiv3808541516 ul {margin-bottom:0in;}-->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 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> 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
To: 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 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> 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 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>
To: "sugarshot@xxxxxxxxxxxxx"<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
To: 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
To: 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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