ANALYZING FOREIGN SAMPLES WITH EXTREMELY HIGH CALORIFIC VALUE
We had a case in Hungary where one of our customers was analyzing carbon fibre wool samples with the DDS Calorimeters E2K Oxygen Bomb Calorimeter System. The system experienced a melt-down of the stainless steel crucible inside the bomb vessel during the determination. This extremely volatile sample has a high calorific value and is highly combustible.
In this case the sample was too large and the temperature rise inside the calorimeter reached above melting point, hence the crucible melted.
Photos: Here is an example of the melted deflector plate after the determination
Photo: Here is an example of the melted electrode and crucible.
HOW TO ANALYZE VOLATILE SAMPLES WITH HIGH CALORIFIC VALUE
- Firstly, reduce the sample size to below 0.1 grams. In the case of the carbon fibre wool samples we recommend a sample size of 0.034 grams.
- Reduce the oxygen pressure to 20 bar (2000kPa).
- Use a volatile glass or ceramic crucible, which can withstand the higher temperatures. (See image below)
- We also recommend using the DDS supplied gelatin capsules and the spiking technique to analyze these samples. (See image below)
When analyzing these samples, it is advisable to start off by analyzing a very small sample (as per above) and then increasing the sample size as you go. Also, a good idea is to keep a check on the temperature rise of the vessel.
Tips for analyzing foreign samples with high calorific value:
- Reduce sample size below 0.1g.
- Reduce oxygen pressure to 20 bar.
- Use glass/ceramic crucibles.
- Use gelatin capsules & spiking technique.
For more assistance or tips for running foreign samples and how to prepare these samples, email us at calo@ddsystems.co.za.
