What is the primary purpose of a boiler's tri-cock?

The primary purpose of a boiler's tri-cock is to indicate the water level within the boiler system. The tri-cock, which consists of three valves, provides a means for operators to check the water level in the boiler visually. This is crucial for safe boiler operation, as maintaining the proper water level is essential to prevent overheating and damage to the boiler components.

The design of the tri-cock allows for a more reliable and immediate understanding of the water level, as it can show whether the water level is adequate or if it is too low, which could pose a risk of damage. Additionally, it allows for the detection of water carryover, which could lead to operational issues. Understanding the water level is vital for the boiler's safety and efficiency.

In contrast, while measuring pressure, draining the boiler, and purging air are important functions associated with boiler operation, these are not the primary functions of the tri-cock. Each of these functions is managed by other specialized valves or instrumentation within the boiler system.