| 摘要 |
Contaminated fuel oil from the crankcase of a marine engine is tested for harmful amounts of strong acid by mixing a measured volume of the oil with a measured volume of a solution of an indicator, which changes colour in the presence of strong acid, the solution of the indicator containing a sufficient amount of basic material, e.g. potassium hydroxide, so that the indicator does not change colour, and thereby indicate harmful acidity, unless the acidity of the sample of oil is such that at least 0,05 milligrams of potassium hydroxide are required to neutralize 1 gram of oil. A preferred indicator solution contains 0,005% by weight Bromo Cresol Green and 0,0008% by weight potassium hydroxide in water. The test may be carried out in a bottle graduated at 4,5 cc. (level A), 29,5 cc. (level B) and 34,5 cc. (level C). The oil sample is poured into the bottle to level A, then the indicator solution to level B, and finally kerosene (or heptane) to level C. The contents of the bottle are shaken vigorously for at least one minute, and then allowed to settle. The colour of the bottom liquid layer is then observed by transmitted light. If the colour is yellow or green, the oil sample has a significant concentration of strong acids. If the colour is blue, the sample contains no significant concentration of strong acids. |
