Question 259General Subjects - Assistant Engineer

The correct answer is C. The spring force acting downward on the disc is a valve opening force, and the sensed pressure acting upward on the disc is a valve closing force. This is because the spring force works to push the disc open, while the sensed pressure works to push the disc closed, in order to maintain the desired pressure in the huddling-chamber safety valve. The other options are incorrect because they describe the forces in the opposite way. The spring force should act to open the valve, not close it, and the sensed pressure should act to close the valve, not open it.