What is the primary purpose of a coalescer sample?

The primary purpose of a coalescer sample is to verify water separation. A coalescer is a specialized filter designed to remove water and other impurities from fuels, particularly in the context of gas turbine systems. By capturing water droplets and allowing them to merge or "coalesce," the coalescer enhances the effectiveness of water separation from fuel.

When sampling a coalescer, the focus is on determining how well it is performing its function of separating water from the fuel. This is crucial because water contamination can lead to serious operational issues such as corrosion, reduced combustion efficiency, and potential damage to engines. Regularly verifying that the water has been effectively separated ensures that the fuel quality remains high and that the gas turbine operates smoothly.

The other options, while relevant to fuel quality, do not directly address the specific function of the coalescer sample. Checking for sediment is typically done through different filtration methods, detecting fuel contaminants may involve broader sampling techniques, and ensuring water purity focuses on the overall quality of water without placing emphasis on fuel separation processes. Thus, the correct option emphasizes the coalescer's designed purpose of promoting and confirming the separation of water from fuel.