access panel markings

[bdoug10]

Not sure what they are called but like a manhole in the ground but not as big usually has pipes in them

Have a blue one with AV on top any one no what it is?

[BrettM]

Probably an air valve. Air compresses at a higher pressure in pipes compared to water, so air valves are normally installed at the highest points of a system to relieve the pressure.

[bdoug10]

Thanks