Which accumulator is described as consisting of a cylindrical body with an internal piston and usually nitrogen as the gas load?

• A. Piston-type
• B. Bladder-type
• C. Direct contact-type
• D. Diaphragm type

Answer: (A)

Storing hydraulic energy by compressing a gas with a movable element inside a cylinder is the key idea. In a piston-type accumulator, a cylindrical body houses a piston that divides fluid on one side from gas on the other. The gas side is precharged with nitrogen. When hydraulic fluid enters, it pushes the piston, compressing the nitrogen and storing energy. The nitrogen load provides the needed compressibility and an inert, stable gas source, giving predictable energy storage and a quick pressure boost when demand returns. The piston’s movement and the gas precharge determine how much energy is stored and how the system responds to fluctuations. Other designs use a bladder or diaphragm to separate gas from fluid, or aren’t defined by a piston in a rigid cylinder, so they don’t match the description as closely.