A dual air vent assembly for wet pipe fire protection sprinkler systems allows air or gas to vent from system pipes as they fill, without spilling any water into the fire-protected environment, even if an air vent valve, operative to discharge air or gas but not fluid, fails. A shut-off valve is upstream of the first air vent valve, and a reservoir is downstream of it. Small amounts of water that escape the first air vent valve are collected in the downstream reservoir, and evaporate. The reservoir also collects fluid if the first air vent valve fails. In response to fluid in the reservoir at or above a predetermined level, the shut-off valve is actuated to arrest the flow of fluid into the first air vent valve. No water escapes the assembly, even if the first air vent valve fails. The shut-off valve may be electronically or mechanically actuated.