1. Every 3 tests, the inside of the oil cup and the outside of the inner electrode must be wiped with a clean cloth containing alcohol or petroleum ether.
2. When the test oil sample has a lot of impurities, it must be filtered with oil filter paper, and there is no visible impurities before pour it into the oil cup for experiment.
3. Before each use of the instrument, it is necessary to check whether there is any looseness between the inner electrode parts. If it is found, it must be tightened before the experiment.
4. Before each use of the instrument, it is necessary to check whether there are impurities inside the oil cup and outside the inner electrode. If found, it must be wiped with a clean cloth containing alcohol or petroleum ether before performing the experiment.
Note: During the experiment, the distance between the inside of the oil cup and the outside of the inner electrode is only 2mm. The errors of the above 4 precautions will cause the change of the oil cup gap, which will cause a short circuit of the oil cup and cause irreversible damage to the instrument.