Stopper for closing filling hole in battery - has curved slots in top of head to cooperate with tool which screws stopper into hole

摘要

The stopper consists of a bush (1) that screws into the filling hole of the battery and has a small outlet hole (3) to allow evolved gas to leave the battery. The head of the bush has a recess connected via the small outlet hole to its hollow threaded shank (2). Curved slots (5) are located in the top of the head to co-operate with a tool that screws the bush into the filling hole. A porous substance with numerous caoilliary channels is located in the recess. A plug fits into the recess and holds the substance in place. The substance traps acid droplets carried by the evolved gas and prevents them leaving the battery and corroding the outside of the casing. The substance also removes water vapour. The substance may be filter paper, polyethylene granules or porous plastics.