What are try cocks used for?

Try cocks serve as a secondary means to determine water level in a steam boiler. They are small valves located on the boiler that allow operators to manually check the water level visually. This is particularly important as it provides an additional safety measure alongside the primary water level gauge. Using try cocks can help confirm whether the reading on the gauge glass is accurate, allowing for immediate assessment of the water level within the boiler. This function is critical because maintaining the correct water level is essential for safe boiler operation, preventing conditions that could lead to overheating or boiler failure.

The other options do not align with the purpose of try cocks. Checking fuel flow relates to the fuel supply system, not the water level. Releasing excess steam is managed by the safety valve or blowoff valves, and monitoring pressure levels is typically done through pressure gauges, not through try cocks. Thus, the use of try cocks specifically for water level confirmation is a crucial aspect of steam boiler operation.