Foire aux questions - Calorimètres
Which calorimeter is most suitable for my application and requirements?
The main questions that should be answered are as follows:
- 1. How many experiments do you plan on conducting in a day?
- 2. Are there any standards that have to be followed, such as ISO, ASTM, DIN, GB, GOST etc.?
- 3. Do samples contain halogens and sulphur and if so, what is the concentration (approximately)?
- 4. Is it required to analyze the halogens and sulphur content after the calorimeter experiment has concluded?
- 5. Do you prefer any of the following methods: adiabatic, isoperibol, static jacket isoperibol, dry or dynamic?
How do I know my calorimeter is still in calibration?
Most customers operate their calorimeters with control charts. After calibrating the unit, check runs are performed with benzoic acid, for instance. The results of these check runs have to match the certified calorific value of the benzoic acid within a defined range. The definition of the range is laid out in standards and the frequency of doing these checks differs from one a day, to one after and before every sample. The control charts show the performance of the unit under the previously described circumstance over a long period of time.
How often do I have to calibrate the calorimeter?
The control chart also shows when a new calibration might be required.
What are the min. and max. calorific values that I can measure with the calorimeter?
The max. allowed energy input into our calorimeters is 40,000 J. The calorific value of a sample is always expressed in energy per weight (J/g). Based on that information, you can adjust the weight of your sample such that it does not exceed 40,000 J. The energy amount created by the sample should not be significantly higher than the one obtained during calibration with benzoic acid. Our calorimeters do have a high measuring sensitivity and can detect low quantities of energy. For example, the ignition energy of 70 J can be measured with an absolute error of ± 20 J. The relative error rises naturally (± 30%) hyperbolically the smaller the energy input is. If your sample has a very low calorific value you can also use combustion aids, since they add energy to the calorimeter to minimize the error.
When do I have to send in the decomposition vessel for high pressure inspection at IKA?
We recommend checking the vessel after 1000 experiments or after 1 year of operation, whichever comes first. During the overall inspection process we perform both a high pressure and an operating pressure test. A new certificate will be issued for the vessel after it has passed both of these tests. More detailed information can be found in the manual of your calorimeter and/ or the manual of your decomposition vessel. Alternatively, you can always contact your local service department for further information and assistance.
Where do I find a list of spare parts and how many of these do I need?
We offer sets of spare parts that include parts for 1000 experiments e.g. 1 year operation. The actual amount of spare parts can vary based on the application. If a specific spare part is required, you can find further information in the service section of the operating manual. In addition, under the “Service” section of our website (www.ika.com), you can download service drawings with detailed descriptions of each part. Alternatively, you can always contact our service department for further information and assistance.
How can I get the gross and net calorific value – easily explained? A calorimeter measures the preliminary gross calorific value of the sample. To get the gross calorific value, correction calculations are required for the acids formed during the combustion. For instance, the method of titration used to obtain the amount of nitric acid and sulphuric acid are described in detail in the standard ISO 1928. To get to the net calorific value, further corrections need to be applied concerning the amount of water that was formed during the combustion from hydrogen. Based on the state (dry, analytical moisture, as received) your sample was in before combustion, further corrections may apply. Moistures are determined by drying the samples. The Hydrogen content is usually measured with an elemental analyzer. For a more detailed explanation, we ask you to study the standards you might have to use depending on your application requirements.