The Spiking Method - Using DDS Gelatine Capsules


Before proceeding with the spiking method, make sure you’ve determined the spike value when using the DDS Gelatine Capsules.

The spike value is obtained by running 2-3 gelatine capsule samples and calculating the average energy value. This value is the spike value.


  • Place the empty crucible onto the balance and press “Tare” to clear the weight of the crucible.
  • Place the gelatine capsule into the crucible using the tweezers and take note of the mass.
  • Enter the noted mass value into the calorimeter as the SPIKE MASS : Press Esc, SPIKE M, Enter, type in the value, and press Enter again.
  • With the gelatine capsule still on the balance, press “Tare” again to get a 0.000g reading.
  • Fill the gelatine capsule with the sample, and close it. Place the capsule into the crucible and weigh it. Take note of the mass.
  • Enter the sample mass on the calorimeter. With the sample still on the balance, press F5 on the calorimeter, then Enter.
  • Enter the Spike Value (noted when running gelatine capsule samples to calculate spike value) : Press Esc, type SPIKE V, press Enter, type the value, and press Enter again.
  • Place the weighed crucible and sample in the bomb vessel, close the lid and fill it with oxygen to 3000kPa (30 bar).
  • Place the vessel inside the calorimeter and close the lid.
  • The calorimeter will automatically run through the Initial, Main (Firing), and Final phases of the determination.

When the analysis is complete, the results will be displayed on the calorimeter and the calorimeter lid will open automatically.

  • Take note of the final calorific value.
  • Remove the vessel from the calorimeter and place it into the cooler.
  • Place the warm vessel into the cooler and leave it to cool. When prompted that the vessel is ready for use, remove it from the cooler.
  • Place the vessel on the counter, and de-fill the oxygen pressure using the de-filler cap. Continue until all pressure is removed.
  • Remove the bomb vessel lid and inspect the crucible for any residue or unburnt sample remaining in the bomb.

The same spiking method can be applied with Benzoic Acid Tablets.

DDS Calorimeters have a default set spiking value of 26.454MJ already entered on the calorimeter for spiking. The default value can be applied when using DDS Benzoic Acid Tablets.


Why use gelatine capsules? Some samples burn extremely fast and result in an explosion, throwing the sample out of the crucible. To solve this, we use a gelatine capsule. What is the spike value? Before analysing the sample, we need to determine the energy value of the gelatine capsule so it can be subtracted from the sample's final energy value.

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The spiking method is called for when a sample has a very low CV or burns reluctantly. Then a better burning material is added to the sample to help the process. The better burning sample is the spike. The ‘Spike’ must be of a known calorific value, usually benzoic acid of approx. 26.454MJ/Kg. On some occasions a Gelatine Capsule (CAL2K-4-GC) or Crucible Cover Disc (CAL2K-FLDS) needs to be as a Spike.

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What is spiking? If a sample does not ignite easily or not at all in a calorimeter, then the spiking method of ignition can be used to promote complete combustion of the sample. Only once the sample is completely burned can an accurate determination of the sample be ascertained. A combustion aid is added to the sample, like a Benzoic Acid Tablet...

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