Emergency Vents (pressure relief only) are used on above ground tanks as a code requirement and helps prevent tanks from becoming over-pressurized and rupturing if exposed to fire, UL listed.
3” Emergency Vent, 8 oz/sq in. opening pressure, with 59,900 CFH @ 2.5 PSI Venting Capacity, UL Listed.
4” Emergency Vent, 8 oz./sq. in. opening pressure, with 119,750 CFH @ 2.5 PSI venting capacity. UL Listed.