What purpose does a siphon serve in a boiler system?

A siphon in a boiler system primarily serves to prevent live steam from directly reaching pressure controls. This function is crucial because pressure controls need to operate with water or a non-steam medium to ensure accurate pressure readings and prevent erratic operation that could occur if steam were to directly affect these controls. By using a siphon, steam is effectively kept separate from sensitive instruments, thus maintaining the integrity of the pressure control system.

In the context of the choices, enhancing steam quality specifically pertains to the treatment and management of steam to ensure it meets certain standards, which is not the primary function of a siphon. Regulating water inlet pressure is typically managed by dedicated valves and pumps rather than a siphon, and ensuring efficient fuel combustion relates more to combustion system components rather than the water or steam handling aspects that a siphon addresses.