New York Low Pressure Boiler Certificate of Fitness (COF) Practice Test 2025 - Free COF Practice Questions and Study Guide

The fuel oil is atomized in the spinner or atomizer cup. This component of the burner plays a crucial role in transforming the liquid fuel oil into a fine mist or spray, which is necessary for efficient combustion. The atomization process ensures that the fuel is properly mixed with air, allowing for a more complete and efficient burn, which helps to maximize energy output and minimize emissions.

In contrast, the storage tank is where the fuel is held before it is used, and there is no atomization happening at this stage. The compressor unit, while important for delivering air to the burner, does not directly participate in the atomization of fuel oil. The return line is part of the fuel oil circulation system but also does not facilitate the atomization process. Thus, the spinner or atomizer cup is essential for achieving the desired spray characteristics, making it the correct answer.