Watts to Temperature Conversion

[briansalomon]

I need to report the temperature of heating elements on heat sealers for medical use that only heat up for 1 to 6 seconds and are various sizes.

I believe the temperature meter on this instrument is a pyrometer using current, voltage and resistance to indicate temperature in deg C.

Does anyone have a formula I can use to certify this type of meter?

[USMC kalibrater]

If you can generate all the information you need to calculate the temperature in the manner you are proposing then....http://hyperphysics.phy-astr.gsu.edu/hbase/thermo/stefan.html#c2
Use the Heat Radiation formula

[briansalomon]

Thanks for that resource. I was able to get a calculated temperature that is useful.

After reading through several manuals for these instruments I did find a direct measurement alternative that may be easier and more accurate. A 40 gauge thermocouple my respond quickly enough for accurate measurements if I use a long enough seal time. The Omega P/N is STC-TT-K-4-36 and is a pack of 5. If I get readings I believe are useful with that I will post back here.

[microwave-kevin]

If the elements are visible how about an infrared thermometer?

[briansalomon]

The elements are only at temperature for a few seconds. They are also oddly shaped and have a cloth type of sheathing so the emissivity (which is almost always a problem to determine accurately) is an issue as well. I did find a 40 gauge thermocouple that may respond quickly enough for this application. The Omega P/N is 5TC-TT-K-40-36. The "40" in that P/N represents the gauge and can be larger if desired. I have some on order and if they work will post back.

[MetVet]

For heat sealers, make sure you make a contact measurement, as in a surface probe or thermocouple attached to a surface that makes contact with the sealing surface.  A regular air temperature thermocouple will not give accurate results.  Something like this http://www.omega.com/pptst/SA1XL.html

[microwave-kevin]

Looks like it would do the job, 0.12 response time

Is temperature to be measured on the heater element or the cloth which I assume is in contact with whatever is being sealed (melted)

[briansalomon]

It's on the cloth.

[briansalomon]

Thanks. All you guys gave me some good information. I did find that a very small gauge thermocouple gives a fast enough response time for this application.

I'm good to go.

[mlangfield]

I suggest a thermistor type sensor, much quicker responding and more accurate.

[briansalomon]

I found that the 40 gauge thermocouple responded very quickly. The sensor needed to fit in a tiny gap and respond to a 200 deg C change in approximately 5 seconds.

Here is a pretty good white paper on impulse heat sealers.

http://www.packworldusa.com/pdf/Packworld_Validation_Guide.pdf

I like my 40 gauge thermocouple better than the one they are using (mine are certified in a drywell) but any temperature sensor that responds quickly enough, has the required accuracy and will fit into the clamps will work.