🔍 Key Concepts
• Function of tri-cocks on a boiler water column (high, normal, and low indicators)
• Relationship between NOWL (Normal Operating Water Level) and the safe steaming range in the drum
• How opening each tri-cock tells you if the boiler level is above, at, or below that point
💭 Think About
• When you crack open the upper, middle, and lower tri-cocks one at a time, what should come out (steam, water, or a mix) when the boiler is at its proper operating level?
• Which tri-cock position best represents the center of the safe water level range, rather than the absolute high or low limit?
✅ Before You Answer
• Identify which tri-cock is intended to indicate high level, which indicates low level, and which indicates the normal level.
• Think about boiler damage: would you want the NOWL to be right at the high limit, right at the low limit, or somewhere between them?
• Visualize the water line in the drum and water column when the gauge glass shows a normal level—is that line aligned with the top, middle, or bottom tri-cock?