What is NOT a purpose for a true accumulator vessel?

A true accumulator vessel serves important functions in various systems, particularly in refrigeration and hydraulic applications. The primary purpose of an accumulator is to store energy or fluid, thereby aiding in managing system pressure and enhancing operational efficiency.

Maintaining a normal operating liquid level is not a primary function of a true accumulator vessel. Rather, accumulators are utilized to absorb fluctuations in pressure and flow that occur within the system. They can provide high-level protection by acting as a buffer during sudden changes, and they may also include relief valve protection to prevent overpressure scenarios. Additionally, they can be integral to the refrigeration process by helping to manage the coolant and ensuring it flows properly through the system.

Therefore, while the other options relate to essential safety and operational aspects of a true accumulator, maintaining a consistent liquid level is not a core purpose of these vessels, which is why it is the correct answer to identify as NOT a purpose of a true accumulator vessel.