Calorimeter calibration method

After one gram of coal has burned, its calorific value is transmitted to the inner cylinder temperature probe. The oxygen bomb, inner barrel, water, and other factors in the conduction path will inevitably produce heat consumption, and this series of heat consumption will inevitably give The final measurement result brings a large error, so we must request the value of these heat consumption at a constant water temperature. The unit of the instrument is E, A, and K. It is input to the instrument to perform a temperature compensation. It is the purpose of calibration.

One thing needs special attention, that is, different room temperature will inevitably bring different changes to the water temperature of the outer cylinder, and the thermal consumption of oxygen bombs, inner barrels, and other factors under different water temperatures is also different, so it looks like The relaxed calibration ambient temperature is actually very strict. For example, to do calibration, you can choose any room temperature. First, make sure that the water in the outer cylinder is full, and that it is constant at room temperature for more than 24 hours, assuming today's room temperature. It is 32 degrees, and the single calibration value (ie, heat consumption value E, A, K) is obtained by inputting into the instrument. After the instrument is calibrated to determine that the instrument has reached the national standard, the instrument is ready for debugging. Then, the calibration heat is determined. The consumption values ​​E, A, and K are the 32-degree heat consumption values ​​at room temperature. If the ambient temperature causes a change in the external water temperature, the determination of the heat consumption value at a room temperature of 32 degrees will also result in an error, and the ambient temperature will cause an error. The greater the change in water temperature in the outer cylinder, the greater the error in the results. In general, personal experience is that the change in the ambient temperature does not exceed three degrees. The result is better, but the seasonal temperature changes slowly. In the room, such as air conditioning, the instantaneous fluctuating fluctuation caused by the heat source is not allowed even once.

First, the benzoic acid's calorific value can be seen clearly. For example, it is marked with 26470J. Press the “settings” button on the instrument to enter the setting interface. You will see the first “system” with E, A, and K. , Q four parameters, the front of the E, A, K, is the original parameters do not move it as it is, move the cursor keys simply change Q to 26470 click the "effective" key to deposit, and then will "coal" All parameters in the "raw material" item are modified to 0.000 respectively according to the "effective" key, because, now, calibration is needed. Both calibration and reverse calibration use benzoic acid, and benzoic acid contains no hydrogen sulfide. Water, so, they should be corrected to 0.000, others, ignition heat 150J and wrapping paper heat 0.000 remain unchanged. At this point, all the parameters in the "Settings" screen have been input, and then click "Valid" button to exit. Settings" interface.

Second, the previous work weighing, oxygen bombs do not know to write, press the "calibration" button, re-enter the packet 0.000, if it is 0.000 directly press the "effect key" can be, and then just enter the amount of weighing The weight of benzoic acid in the oxygen bomb is equal to the sample weight. We must pay attention to the weight of the benzoic acid. The weighing accuracy must be accurate to four decimal places, say 0.9998, and the error range is 0.9997---0.9999. It can be used in the range of 09----1.1g. If you lose the sample weight, you can input the water time. For example, if you want to lose 28 seconds, press the number key 28 and then press the “valid” button. Now your work has been completed. Finished, the rest is waiting for the instrument to print the results.

When inputting water time, it is necessary to pay attention to the purpose of filling the water with the inflating nozzle of the oxygen bomb. The purpose is to observe the place where the oxygen bomb inflator and the oxygen bomb will leak as a whole after the water is filled. If there is a bubble continuously overflowing the oxygen bomb, It needs repairs.

The calibration printing result is very simple, namely E, A, K, and three English numbers. It is the heat consumption value of the current room temperature and water temperature that we mentioned earlier. It should be noted that you usually do coal samples or anti- Calibration (using the "determination" key), the ignition time is 5 minutes, and when you do the calibration you press the "calibrate" button, the ignition time is 15 minutes, do not think that the instrument is broken, because the purpose of calibration is Calibrating the instrument to find the exact value of heat consumption, the mixing time will be longer before the water temperature of the inner tube is very stable. . . .

A calibration result has no contrast. Therefore, at least two or more calibrations are required. Generally, two to three calibrations can be used to find a satisfactory result. Compare E in two or more calibration results, for example, A difference from E in the third calibration result does not exceed 40 J. E is added to the two results and divided by 2, that is, the average value is obtained. Then, A and K in these two results are averaged. Find the value. Press the “Set” button again to enter the “Set” button to enter the setting interface. In the first “System”, there are four parameters: E, A, K, and Q. You will find the E, A, K, The average value is input separately, and it can be saved by pressing the "valid key". The others will not move, and then the "active" key is pressed again to exit the "setting" interface. At this point, the calibration work is completed.