Question 255Steam Plants - Assistant Engineer

The correct answer is C) high steam pressure. The solenoid valves in the fuel oil supply line to an automatically fired auxiliary boiler are automatically closed by high steam pressure. This is a safety mechanism to prevent overpressurization of the boiler system. When the steam pressure rises above a certain threshold, the solenoid valves will automatically shut off the fuel supply to the boiler, stopping the combustion process and preventing potential damage or explosion. The other options are incorrect because they do not directly trigger the automatic closure of the fuel oil supply solenoid valves. A decrease in feed temperature (A), high furnace air pressure (B), or low steam pressure (D) may have other effects on the boiler system, but they do not directly cause the fuel oil supply to be shut off in the same way that high steam pressure does.