The PAV is an automatic float type air vent used to reduce the amount of air trapped in a pressurized fire sprinkler system. Reducing the amount of air in a fire sprinkler system is essential to help protect the system piping from the effects of corrosion that is often found at the air/water interface in the fire sprinkler system piping. Removing as much air as possible will also have a positive effect on the performance of vane type waterflow detectors. The operation of vane type waterflow detectors can be delayed or prevented if too much air is trapped in the system piping. The intent of the product is to vent as much air from the fire sprinkler system as possible. The PAV provides automatic venting of air as the system is being filled. Furthermore, trapped air can also be vented as the air in the system migrates to the vent location over time. The air vent will automatically close when water reaches the vent. The PAV provides a 1/2" NPT-male connection which will allow installers to safely pipe to a drain, any inadvertent discharge of water that is inherent in the operation of the automatic air vent.