- Whole diameter:20″
- Blinding Hole Design:
In the main plate of the manhole cover , There are three blinding holes can be installed with Vapor Vent Valve , Optic Sensor , Dip Tube or External Vacuum Valve according to user`s demand.
- Benefit and Features :Aluminum alloy surface is treated by oxidation to improve the anti-corrosion.
Can be installed double P/V vent valve according to requirement to increase the flow rate of air