Question 442Steam Plants - Assistant Engineer

The correct answer is D) steam pressure acting on the enlarged area of projecting lip or ring. In a huddling chamber safety valve, once the initial lift of the valve disc occurs due to excessive static boiler pressure, the continuing lift of the valve is driven by the steam pressure acting on the enlarged area of the projecting lip or ring around the valve seat. This enlarged area creates a reactive force that pushes the valve further open as the steam pressure increases, allowing the valve to continuously release pressure and prevent a dangerous buildup. The other options are incorrect because they do not accurately describe the mechanism behind the continuing lift of a huddling chamber safety valve. Options A, B, and C do not directly relate to the design and function of this type of safety valve.