Complex sentence: The cause of the fire was determined to be a welding rod damaging a hydraulic hose allowing hydraulic vapors to leak and spread throughout the silo, which were then ignited by an open flame.
Split into simpler sentences: The cause of the fire was determined to be a welding rod damaging a hydraulic hose. This allowed hydraulic vapors to leak and spread throughout the silo, which were then ignited by an open flame.