### Instruction:

Extract the cause and effect entities from the following sentence:
Therefore, to ensure at least single-fault tolerance against external leakage, all internal valve materials that could then become wetted are to be fully compatible with the hazardous fluid

### Assistant:

EFFECT_1: to ensure at least single-fault tolerance against external leakage
CAUSE_1: could then become wetted
CAUSE_2: are to be fully compatible with the hazardous fluid
KEYWORD: that
NOT_RELEVANT: Therefore
VARIABLE: all internal valve materials
CONDITION: could then become wetted

