Gravity Scale Value

The gravity scale value is designed as an indication of the (potential) severity of an accident. Figure 69 shows a schematic of how the Gravity Scale Value is calculated. The sum of the hazard aspect score is multiplied by the location Weight Factor. The resulting number is then converted to a number in a scale from 0 to 12.

LW Location Weight Factor

To calculate the final score, the location weight factor has to be multiplied with the total hazard aspect score. The location weight factors for different locations are shown below. These are based on

Open sea 1,0

Vulnerable area 3,0

Populated area 3,7

Final Score to Gravity Scale Value

The resulting final Score (SF) can be converted into a gravity scale value between 0 and 12 with the following formula:

Calculation of Gravity Scale Value for spills with multiple substances It is not uncommon for a spill to comprise multiple substances. In such a case, the hazard aspect scores of these substances should be compared: For each hazard aspect, the highest resulting Hazard Aspect Score will be taken into account.

Examples Table 35 shows some examples of the use of the gravity scale for accidental spills: on the left side of the scale one finds crude oil spills of different quantities spilled in or close to a vulnerable area and on the right side of the scale some examples of 20 tonnes (e.g. one container) of other hazardous substances are shown.

The top 25 substances from the top 100 substances with the highest risk can be determined with the gravity scale values see Figure 70.