抄録
Induction Period Method, designated by ASTM D525, has been known as one of methods to evaluate the oxidation stability of gasoline. The gasoline in a bomb is oxidized under elevated pressure of oxgen, and in the absorption process of oxgen the time required for the gasoline to reach a finite rate of pressure drop is defined as the induction period.
This method may be utilized to predict the storage stability, that is, the potency to form gum in storage of gasoline.
In this paper, the effect of factors, light irradiation, detergents, and bath temperature, on the induction period, and the limit of the precision of this method have been investigated. The conclusions drawn from these experiments are as follows.
1) The effect of light irradiation: The history of light irradiation by the fluorescent lamp reduces the induction period of the sample. It is expected that the induction period will be reduced by 10% provided the gasoline in a colorless container is kept for 48 hours on a testing bench. Therefore, the sample should be storaged in a colored container or in a cool and dark place.
2) The effect of detergent: The alkaline detergent shows insufficient detergency, and the use of the detergent gradually reduces the induction period as experiments are repeated.
3) The effect of bath temperature: A consideration should be paid on the position of heater to be mounted and the flow rate of water to be supplied in the design of the water bath to heat the bomb.
4) Precision: The limit of the precision of this method, which is easily attainable, is about 0.3% as coefficient of variation (1006/x).
