What is the use of steam cock & drain cock on water level indicator ?

The water level indicator shows the level of water in the drum. The steam cock valve connects to the top portion of the drum (where the steam accumulates) to the water level indicator, this steam cock valve provides a path thru which steam can travel (into the water level indicator) as well as a point isolation if maintenance is required. The drain cock valve is provided so that the water level indicator can be drained for maintenance if required.