Opening each cock in turn and watching whether it discharges water or steam tells the operator roughly where the level is, independent of the gauge glass. They are a backup when the glass is broken or doubtful. Water comes out as a solid stream that flashes; steam comes out as a clear jet that turns white a few inches away.
Glass is cracked, so run the try cocks every half hour and log it until the new one's in.
Open a try cock slowly and stand to the side; the discharge is boiler water at full temperature.
Also heard as
- gauge cocks
- trycocks
Related terms
Water column
A vertical chamber piped to a steam boiler's steam and water spaces that carries the gauge glass and level controls.
Gauge glass
The glass tube or window on a steam boiler that shows the operator the actual water level.
Low-water cutoff
A safety control that shuts the burner off when the boiler water level drops below a safe point.