C801-560/580 Aluminum Manhole Cover C801-560/580 Aluminum Manhole CoverInstalled on the top of the tank, it has builtin respiration system and emergency vent.1. Light and strong2. Emergency vent relieving pressure is from 21 to 32 KPa. The Max.free air is 7000m3/h.3. It have one or two breathing valve inside, the pressure in the tank can be adjustedautomatically. 

C801-560/580 Aluminum Manhole Cover