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Operation procedure of the Delit auto-ignition point tester: 1. After unboxing the auto-ignition point tester, carefully remove the packaging, check the accessories against the packing list to ensure there are no damages, and place the instrument steadily on the workbench. 2. Connect the ground wire to ensure safety. 3. Insert the power plug with a properly connected ground wire into the corresponding socket. 4. Place the triangular flask inside the heating chamber, connect it to the power cable, press the power switch, and set the same temperature value (for the three instruments). The three heaters in the heating chamber then begin to regulate the temperature; the test procedure follows the methods specified in the national standards. Operation of the temperature controller for the auto-ignition point tester: 1. Press the SET button for 3 seconds to enter the PID parameter adjustment menu. Press the SET key to select the parameter you wish to modify. Press the AT key briefly; the digital display will flash, allowing for value adjustment. Use ▲/▼ keys to change the data, and finally press SET to confirm. To scroll down, keep pressing the SET key. When in the setting modification mode, if no action is taken within 25 seconds, it automatically returns to the measurement mode. 2. The instrument automatically enters temperature control mode; once the temperature reaches the set value, the test can be carried out. For specific test items, refer to the detailed test guidelines. Setting of the given control values and self-tuning operations for the auto-ignition point tester: 1. Setting of given values: While the auto-ignition point tester is in measurement mode, press the SET button to make the digital display flash; press the AT button to shift through the values, use ▲/▼ to make modifications, and finally press SET to confirm. 2. Auto-tuning operation: Once the user’s system is properly tuned and the equipment is functioning correctly, and when the PID is not in on-off control mode (parameter P ≠ 0), if the user is unsure how to set the PID parameters, they can use the auto-tuning function. The procedure is as follows: Hold down the “AT” button on the panel for about 3 seconds; once the AT light turns on, the instrument enters auto-tuning mode for the PID. To ensure accurate setting of the PID parameters, it is recommended that the user avoid making any changes to the instrument or the system at this time. Once the tuning is complete, the AT light will go out, the instrument will update the PID values, and it will automatically enter regulation mode. If the user wants to exit the tuning process early, they can hold down the AT button for more than 3 seconds until the AT light goes out. If necessary, the user can make appropriate adjustments to the P, I, and D parameters automatically set during self-tuning, primarily the P parameter, in order to achieve better results. A smaller value for P results in a faster response; however, if it is too small, the system becomes unstable ； As I decreases, the stabilization time shortens; too small a value for I also leads to system instability. 3. Pre-set the temperature control device to the pre-ignition temperature of the fire-resistant fuel, one by one, so as to maintain the temperature in the middle of the heating bath at the set value. This instrument has a preliminary temperature setting of 530°C before leaving the factory; slight variations may occur due to differences in the operating environment. Adjust the temperature according to the instructions to ensure that the temperature difference between the top, middle, and bottom of the 200 mL conical test flask – namely, the temperatures at these three points – remains at 1°C. 4. Use a syringe to inject 0.05 mL of the sample into the flask and quickly remove the syringe. 5. Start timing and observe the inside of the conical flask using the mirror on the heating furnace; if no flame is visible within 5 minutes, stop timing – in this case it is considered that the sample does not burn easily at that temperature. Use a hair dryer to blow out the contaminated gases from inside the conical flask. Then increase the temperature by 10°C and repeat the experiment. At least 15 minutes should pass between the two tests. If a flame is observed, record the temperature and reduce the test temperature by 5°C before repeating the process. If a flame appears again, reduce the temperature by another 5°C and repeat until no combustion occurs. The lowest temperature at which spontaneous combustion occurs is known as the autoignition point. The test procedure shall comply with the power industry standard DL/T706-1999.