What is the purpose of a blow-off valve in steam systems?

The blow-off valve in steam systems plays a crucial role in maintaining system safety and operational efficiency by releasing excess water from the boiler. When water accumulates beyond the desired level, it can create unwanted pressure conditions, leading to potential hazards. The blow-off valve is specifically designed to expel this excess water, which helps prevent pressure from building up to dangerous levels. This process not only ensures the safety of the system but also contributes to the proper functioning of the boiler by maintaining the necessary water level for optimal steam production.

Other options provided refer to different functions within a steam system: controlling steam pressure involves pressure relief valves, regulating fuel supply pertains to burners and fuel systems, and managing steam quality relates to superheating and drying processes. Each of these roles is vital, but the blow-off valve's primary function is indeed to release excess water and safeguard against pressure buildup.