Question 132Steam Plants - QMED

The correct answer is D) exhaust to pressures above atmospheric pressure. Auxiliary turbine feed pumps typically do not require an external source of gland sealing steam because they exhaust to pressures above atmospheric pressure. This means the pressure differential between the pump's internals and the atmosphere is sufficient to prevent air from entering the pump, eliminating the need for an external steam supply to create a positive pressure at the shaft seals. The other answer choices are incorrect because: A) operating at relatively low pressures does not inherently eliminate the need for gland sealing steam, B) the use of carbon packing rings is not the reason auxiliary turbine feed pumps do not require external gland sealing steam, and C) the amount of axial thrust is also not the determining factor.