Question 248General Subjects - Assistant Engineer70% to pass
How would the illustrated valve respond to a complete loss of charge from the remote bulb-to-control diaphragm power element if the valve is used as a temperature control valve for a steam-heated heavy fuel oil service heater? Illustration GS-0045
AI Explanation
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.
Related Questions
#246 When the oily-water separator, shown in the illustration, is in operation and processing clear bilge water, what should be the internal water level? Illustration GS-0153 #247 How would the pressure setting of the illustrated self-contained, internal-pilot, piston- operated steam pressure-reducer be raised to a higher set point? Illustration GS-0044 #249 In the illustrated self-contained, internal-pilot, piston-operated steam pressure- reducing valve, what statement is true concerning the pilot and main valves? Illustration GS-0044 #250 Suppose the illustrated self-contained, internal-pilot, piston-operated temperature control valve is part of the temperature control system for a steam-heated heavy fuel oil service heater for a steam boiler. If there was a decrease in demand for fuel by the boiler, what statement correctly represents how the valve would initially respond? Illustration GS-0045 #251 Suppose the illustrated self-contained, internal-pilot, piston-operated temperature control valve is part of the temperature control system for a steam-heated heavy fuel oil service heater for a steam boiler. If there was an increase in demand for fuel by the boiler, what statement correctly represents how the valve would initially respond? Illustration GS-0045