What is Calorific Value?
Calorific value can be defined as the amount of heat released by a unit mass of a sample when burned with oxygen in a constant volume vessel. The calorific value (or heat of combustion) refers to the heat released, including the oxidation of other elements such as sulfur, by burning all carbon and hydrogen with oxygen to form carbon dioxide and water contained in the sample with a bomb calorimeter. The calorific value can be expressed in calories (cal), British thermal units (Btu), or Joules (J).
What is Bomb Calorimeter?
A bomb calorimeter is a device designed to measure the amount of heat a sample releases during a combustion reaction. The calorimeter creates a system isolated from the environment for analysis, that is, there is no heat exchange between the device and the environment. In this way, calorific value analyses are carried out sensitively with the bomb calorimeter.
Certified reference samples, that is, standard materials with known values, are used for the measurement accuracy of the bomb calorimeter. The most used of these is benzoic acid. In certified benzoic acids, the calorific value of each tablet is known within a certain deviation range. With a bomb calorimeter, calorific value is calculated by burning benzoic acid or a sample of known value in a high-pressure environment. The result obtained from the bomb calorimeter is compared with the certificate value, if the result obtained is within the reference range specified in the certificate, the measurement is considered correct. The measurement is incorrect if it is not within the reference range. measurement inaccuracy: Unsuitable environmental conditions, system problems, incorrect analysis preparation or incorrect calibration of the bomb calorimeter, or system errors can be caused by different reasons such as incorrect water amount.
You can contact us for detailed information about the bomb calorimeter, to obtain certified reference material (benzoic acid, …) or consumables.
Calorimeter Bomb (Decomposition Vessel)
The calorimeter bomb (decomposition vessel) is a high-pressure metal vessel. It is used as a decomposition vessel in analyses performed with a bomb calorimeter. It ensures that the sample placed inside is safely burned with high-pressure gas (mostly oxygen). For this reason, it must be resistant to high pressure and hydraulic pressure test must be carried out at regular intervals. The calorimeter bomb must be resistant to at least 200 bar pressure. It must be designed in accordance with standards and regularly checked. It is necessary and important that the calorimeter bomb is leakproof, that the pressure tests are carried out in accordance with the ASTM E144 standard, and that it is used by taking into account safety precautions. For information on security measures, you can read our blog article titled " Considerations When Using the Bomb Calorimeter” (calorimeter bomb) or contact us for your questions.
Bomb Calorimeter Calibration
Before starting the calorific value analysis with the bomb calorimeter, analyses should be performed to introduce the system contents and effects to the device and the device should be calibrated. The main purpose of the calibration analysis is to determine the heat capacity of the device by performing the analysis calculations correctly. Heat capacity is the amount of energy required to raise the temperature of a substance by 1 unit. The heat capacity is used by the system while calculating the calorific value as a result of the analyzes performed with the bomb calorimeter. Therefore, it is important to determine the heat capacity correctly.
Certified reference material (benzoic acid) is used for calibration analysis. After performing at least 5 successful calibration analyses using a bomb calorimeter, the RSD (Relative Standard Deviation) value of these analyzes is calculated by the system. The RSD value of the system should be less than 0.17% in order to perform the bomb calorimeter calibration according to the standards set by international organizations (ASTM, ISO, DIN, …). The lower this value, the less the deviation of the calorimeter, and the heat capacity is correctly determined.
After the calibration process of the bomb calorimeter is completed/the heat capacity is determined, you can continue the standard analysis and perform the calorific value measurements of your samples.
Calorific Value Analysis with Bomb Calorimeter
After the bomb calorimeter calibration, standard analyzes/ calorific value analyses of the samples whose value is unknown are performed. Solid and liquid combustible materials can be analyzed with a bomb calorimeter. Bomb calorimeter applications and materials to be used may vary for different sample types. You can contact us for detailed information about bomb calorimeter applications.
Required Before Beginning Standard Calorific Analysis:
o Test Environment - A draft-free environment, protected from direct sunlight and other radiation sources. Thermostatic control of room temperature and relative humidity is recommended.
o Decomposition Vessel - The vessel where combustion takes place, also called the calorimeter bomb. It has high thermal conductivity, resistant to pressure and temperature changes.
o Balance - A laboratory balance capable of weighing the analysis sample to the nearest 0.0001 grams.
o Combustion Wire- The heat that the wire gives to the vessel during ignition must be determined.
o Crucible- It is an open sample slot made of platinum, quartz, or base metal alloys.
o Oxygen- It must be produced from liquefied air, purer than 99.5%, and free of flammable substances.
o Oxygen Charger - Displays the output pressure of the decomposition vessel and the oxygen cylinder, ensures that the necessary connections for filling are made safely, and is resistant to wear against pressurized oxygen.
o Sample to be analyzed - It is a homogeneous sample brought to the appropriate dimensions.
For the calorific value analysis of the samples of unknown value: Weigh 1 gram of the homogeneous sample brought to the appropriate dimensions in the crucible. Pass the burning wire through the slots in the legs of the calorimeter bomb (decomposition vessel). The combustion wire should contact the sample without touching the crucible. Then add 1 ml of distilled water into the decomposition vessel (calorimeter bomb). Close the upper ring by placing the upper part of the calorimeter bomb in the lower vessel. Fill the calorimeter bomb with oxygen gas with the help of the oxygen charging apparatus. After your sample preparation process is finished, start the analysis by placing the calorimeter bomb inside the calorimeter.
You can contact us for information about analyzing different sample types or preparing a detailed analysis with calorimeter.
Applications of Bomb Calorimeter
The bomb calorimeter is a basic laboratory device used in many industries. Bomb calorimeter is used for calorific value analysis of different types of samples. Therefore, the applications for different samples vary.
With Bomb Calorimeter:
o Energetic Materials (Explosive, …)
o Liquid Fuels
o The calorific value analysis of many solid and liquid combustible materials is carried out.
We have extensive application notes for many sample types using the calorimeter IC210. You can contact us to reach the Bomb Calorimeter Application Notes or to get detailed information.
Halogen Resistant Decomposition Vessel for Bomb Calorimeter
While halogens (group 7A elements) are used in many industries, they also pose a risk to nature and the health of living things. Therefore, the use of halogens in the industry should be carried out in accordance with international standards. Preliminary preparation can be made with the Halogen Substance Combustion Unit or Calorimeter IC210 Halogen Mode, which we have developed to determine the amount of halogen in the materials to be used.
The halogen content can also damage the calorimeter bomb structure. For this reason, with the Halogen Resistant Decomposition Vessel, we have developed, calorific value analysis or halogen detection analyses of samples with halogen content can be performed safely.
You can contact us for information or a price quote about the Halogen Resistant Decomposition Vessel.