The purpose of the steam control valves installed in the auxiliary exhaust line is to __________.

Correct Answer: Option C — control steam admission and maintain the proper steam spray pattern in the DC heater

Deaerating feed heaters require precise steam admission to maintain thermal equilibrium and effective deaeration. Control valves in the auxiliary exhaust line regulate the steam flow to ensure the proper spray pattern and temperature, facilitating the removal of non-condensable gases from the feedwater as required by 46 CFR Subchapter F.