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