Scientific Analytical Calorimeter Solutions

How To Measure Powerful Samples


Powerful samples have a very high CV. The highest (nongaseous) is Kerosene at 48Kj/g. All the fuels are not far behind and fat is 37Kj/g. Note that Dynamite is not powerful but fast burning. The vessel and apparatus can handle powerful samples from a safety aspect (Not dynamite!) but in order to maintain the instruments accuracy, the temperature rise of the sample should be within limits of the calibration rise.

Kerosene | DDS Calorimeters

The calibration rise of 0.5g Benzoic Acid is approximately 12 °C. So, the sample rise should be approximately the same.

The rise limits defaults are:


These limits are 50% down and 33% up from the calibration rise of 12 °C.

The limits are un-equally spaced because the heat losses increase more when going up.

The Rise limits are parameters and can be changed from the keyboard.

The temperature rise is proportional to:

  • The mass of the sample
  • The energy in the sample (to be measured)

Burning Powerful Samples

The sample mass should be adjusted so that it produces a temperature rise which is approx. the same as the calibration rise. If the rise limits are violated then the CAL3K issues a warning. The warning can be ignored! Violating the high-rise limit should be avoided because it requires longer cooling time.

Here are the sample masses for calibration with 0.5g Benzoic Acid and the limits:

Expected CV (Kj/g) Expected CV(Kcal/g) Std Mass(12°C) High Mass(16°C)
50 11.9 0.26 0.36
45 10.7 0.44 0.6
40 9.6 0.33 0.44
35 8.4 0.38 0.51
30 7.2 0.44 0.59
26.5 (BA) 6.4 0.5 0.67

The above table assumes a standard calibration with 0.5g Benzoic Acid which yields approx. 12 °C rise. When a high CV sample is expected then the sample mass should be reduced according to the above table.


When the CAL3K issues a Rise limit warning then adjust the mass accordingly. The adjustment is done to operate at the best accuracy. In most application the expected CV range is known before a determination.

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