Question 111Motor Plants - QMED

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 in response to high steam pressure. This is a safety mechanism to shut off the fuel supply when the steam pressure gets too high, which could indicate a problem with the boiler operation. The high steam pressure triggers the solenoid valves to close, cutting off the fuel supply and preventing a potentially dangerous situation. The other answer choices are incorrect because they do not correctly identify the parameter that triggers the automatic closing of the solenoid valves. A decrease in feed temperature, high furnace air pressure, or low steam pressure would not cause the solenoid valves to close in this case.