Question 248General Subjects - Assistant Engineer

The correct answer is B) The valve would fail in the fully open position, resulting in a high fuel oil temperature alarm. This is because when a pneumatic temperature control valve with a remote bulb-to-control diaphragm power element loses its charge, the valve will fail in the fully open position. This is due to the design of the valve, which uses the pneumatic pressure from the power element to close the valve against the force of the spring. When the power element loses its charge, the spring force takes over, causing the valve to fail open and allow maximum flow, resulting in a high fuel oil temperature. The other options are incorrect because A) the valve would not fail closed, C) it is possible to predict the failure mode, and D) the valve would not remain in its previous position.