How does the C-Therm Technology work?

The C-Therm sensor generates heat at the surface. The tested object must be flat in order to evaluate thermal properties. When placed on the sensor, it absorbs some of this heat and the rest of the heat causes a temperature rise at the sensor interface. Insulation absorbs less heat than glass or from the C-Therm technology’s reference, insulation leaves more heat behind than glass. The rate of temperature rise at the interface is evaluated to determine the thermal properties of the sample being tested.

What about calibration?

Both of C-Therm's TCi and ESP product lines are factory-calibrated for greater ease of use for the client.  The calibration standards used by C-Therm are traceable for customer confidence. The instruments are provided factory-calibrated to the client, with a standard reference material for operational qualification. 

How often must I calibrate?

C-Therm recommends a verification of the calibration by the manufacturer once per year.  However, the client is provided their own set of reference materials and as long as they are testing within the performance specifications of the instrument it is the client's decision as to how often to have the sensors re-calibrated. 

Can I touch the sensor while it is operating?

Yes and no. The C-Therm Technology does not become too hot to touch during a test but the tested material or object must be in a constant state during a test to achieve the desired results. If it is moved during a test then a new test is recommended.

How flat does the sample have to be?

The C-Therm Technology tests the properties of the material in contact with the sensor. If the tested material or object is not flat, the air in the cracks or buckles will be tested too. A good "rule of thumb" to use in evaluating whether your sample will test well:  if you can take a nickel coin and balance it flatly on the surface of the sample with the full surface area of one side of the coin contacting the sample - then you your sample will test well with the TCi or ESP sensor.  (A nickel is roughly the size of the active area of the sensor - 17mm diameter.)

How thin of a sample can I test?

The test methodology requires that the heat generated at the interface does not totally penetrate the tested material or object.  The minimum thickness depends on the properties of the material and the length of the test. (Note:  then standard calibration test time for the TCi and ESP is 0.8 seconds.)  Insulation can be thinner than conductive materials. A user can stack thin samples such as film to produce a thicker cross section for testing. The C-Therm Technology can test samples as thin as 0.1 mm (0.004") using a blotting technique (see B1-Testing Thin Oriented Film).

How is this method different from hot plate?

The C-Therm Technology is a one-sided interfacial test method, meaning that the heat produced at the sensor is detected at the sensor. The hot plate method requires the heat generated at a sensor to penetrate the sample and be detected at the other side

What are the advantages?

The test methodology allows for much faster testing, seconds versus hours. Also, tested materials and objects do not have to be machined to precise dimensions for testing.

Are there any drawbacks to the C-Therm Technology?

Yes. The methodology requires that the heat generated builds up at the interface and causes a temperature rise. For this reason the C-Therm Technology is not sensitive enough to test highly conductive materials above 500 W/mK.

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