Why we use low expansion foam on deck and high expansion foam in the engine room?

Low expansion foam is having a more weight to volume ratio as compared to high expansion foam.
If we use high expansion on deck, then wind effect will blow away the foam.
The low expansion foam having sufficient weight to counter the wind force effect. So, it is easier for low expansion foam to form a blanket over fire properly.
In the engine room, wind effect is not present only we need to suppress the flammable gases and to give a cooling effect in the large volume of the engine room. So high expansion foam is good to cover more space in a short time

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