Closure device for lead-acid batteries

A closure device for a storage battery comprising the combination of:

• a housing connected to the storage battery, said housing defining a chamber for containing a liquid level;
• filter means for removing toxic discharge gases from said battery in gas flow communication with said housing chamber, said filter means including liquid conducting means for returning condensed water vapor to said housing chamber;
• and
• liquid-gas contact means for preventing explosion within said housing, said liquid-gas contact means including the combination of an inverted closed-end tube communicating with an outlet for discharge gases from said battery and a generally vertical open-end tube within said housing chamber, said closed-end tube having a side-wall opening at its lower end portion for permitting gas flow into said housing chamber, said open-end tube having a lower end portion with means for forming a liquid seal blocking gas flow positioned in liquid flow communication with said storage battery and an upper end portion positioned within said housing chamber above the level of said side-wall openings in said closed-end tube whereby a liquid level is maintained through which gas discharge from said battery must pass and whereby excess condensed liquid is returned to said battery through said open-end tube.