DDS Calorimeters Feb/Mar Issue | Page 7

WHY HIGH PRESSURE OXYGEN IS USED IN BOMB CALORIMETERS

Oxygen Bomb Calorimeters ( also known as Constant Volume Calorimeters ) are used for various applications in different industries to calculate the heat released from a combustion reaction ( also known as a combustion calorimeter ), the calorific value of the sample , be it any solid or liquid substance like coal and oil , is then measured .
It is known as a constant volume calorimeter as it holds the constant volume and the oxygen at any given pressure ( in DDS Calorimeters we use up to 30 bar ). The sample used for the calorific value determination is prepared and measured , then placed into the vessel and sealed with the bayonet lid / screw lid . The sample is then ignited with an electrical current in the atmosphere of oxygen .

HIGHLY COMBUSTIBLE SAMPLES

In some applications where highly combustible samples are being analysed , nitrogen is used instead of oxygen ( at a low pressure ), for example when burning highly combustible explosives .
If water is formed during the combustion of the sample this will result in another reason for using high pressure oxygen in a bomb calorimeter . The excess oxygen presure assists with the formation of water in the bomb vessel .

HIGH PRESSURE OXYGEN REGULATORS

A High Pressure Oxygen Regulator is used with the DDS Calorimeters range and is fitted to the oxygen supply when installing the system for the first time to ensure that the correct pressure of oxygen is supplied to the filling station or calorimeter ( if using the CAL3K-AP Calorimeter ). The high pressure regulator is an absolute MUST when installing the system and assists with the monitoring of oxygen supply to the filling station , and essentially to the bomb vessel . For the operator ’ s safety and lab safety it must be fitted to the oxygen supply . It is an integral part of the complete calorimeter system when it comes to filling the bomb vessel with oxygen before a determination .
The rise in the temperature is then measured to determine the heat released during the combustion of the sample . The DDS Calorimeters range automatically calculates the calorific value of the sample , eliminating the need for manual calculations from the operator .

DURING SAMPLE ANALYSIS

High Pressure Oxygen is required to ensure the sample burns completely in the bomb vessel . The oxygen assists with the burning of the sample to ensure the sample burns completely for an accurate final result . We recommend using a pressure of 30 bar in the CAL3K Calorimeters to ensure complete burning of the sample .
The older CAL2K bomb vessels require 10 to 20 bar for complete combustion , but a pressure of 30 bar is recommended for all our oxygen bomb vessels to ensure complete combustion .

CONCLUSION

Various components and consumable are used furing an analysis to ensure the bomb vessel is filled with high pressure oxygen . These components all play a part in analyzing samples and the burning of samples within the bomb vessel .
DDS Calorimeters | Feb / March 2017 Issue www . ddscalorimeters . com