means that if you have an equipment to be protected you need at least two branches with equal or less than 50% of the total number of sprinklers needed for that equipment. Example: if you need 3 sprinklers, you will need 3 branches with 1 sprinklers each, because if you have two branches, one will have 2 sprinklers which is more than 50%. The reason is if one branch fail at least 50% of capacity should still remain functional

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