Power Engineering 4th Class - A12 Questions and Answers Rated A+

Power Engineering 4th Class - A12 Questions and Answers Rated A+ Natural draft is produced in a boiler furnace when: a. Hot flue gases condense b. Gases in the stack have more mass than an equal column of outside air c. Gases in the stack have less mass than an equal column of outside air d. Hot flue gases contract so that each cubic meter has more mass c If the power is cut off to an automatic gas valve, the valve will: a. Open widely b. De-pressurize the gas train c. Close immediately d. Close slowly c When draft is produced by natural means: a. Cooler air surrounding the boiler increases draft b. The diameter of the stack will improve the draft c. A short stack is preferred over a tall one d. Fans control the flue gas flow a The Hartford loop will: a. Replace the feedwater check valve b. Prevent boiler water level from going below the lowest safe water level c. Ensure continuous circulation of a hot water system d. Only be installed on multiple-boiler systems b In a float type low water fuel cutoff, the main purpose of the mercury switch is to: a. Open the burner circuit when the level is low b. Activate a low water alarm c. Close the burner circuit when the level is low d. Open the burner circuit when the level is high a When an oil burner is not in use, it should be removed from the furnace; otherwise the heat may cause: a. Carbon to accumulate in the burner b. The rotary cup to slow down c. The burner to corrode d. The fuel to evaporate a Gas burners for heating boilers can be divided into two general classes: a. Pre and after mix b. In-shot and up-shot c. Refractory and ribbon-type d. Mixing and non-mixing a Blowoff valves are used to: a. Reduce the steam pressure on the boiler b. Drain or remove sediment from the continuous blowdown c. Drain or remove sediment from the bottom of the boiler d. Drain or remove sediment from the bottom of the steam drum c On a boiler blowoff system, a valve that requires at least five 360° turns of the operating mechanism to change from fully open to fully closed is known as: a. an isolating valve b. a slow opening valve c. a non-return valve d. a quick opening valve b A solenoid type fuel valve;