The vent’s first stage is designed to equalize pressure while preventing the ingress of water and contaminants, while the second stage is built to activate in response to rapid pressure and heat buildup by opening the vent and allowing expanding gases to escape, which helps deter damage.
Donaldson says the dual-stage vent design also avoids the use of a one-way valve, a rubber flap or other mechanical devices by attaching directly to the housing via a quarter-turn bayonet installation and using the company’s proprietary Tetratex ePTFE membrane to help keep debris and water out of the battery pack.