Which two pieces of information are necessary to determine an equivalent replacement for a defective control valve that is no longer manufactured or available?

• A. Size and type
• B. Material and finish
• C. Brand and model
• D. Operating temperature and pressure

Answer: (A)

Matching an equivalent replacement hinges on two things: the valve’s size and its type. The size ensures the new valve will physically fit the piping and end connections, so you can install it without adapters or leaks and maintain the expected flow path. The type determines how the valve regulates flow and how it behaves in throttling service; different types (for example, globe-style versus ball-style) have distinct flow characteristics and control actions, so using the correct type preserves the intended control performance and pressure drop.

Material or finish might matter for corrosion resistance, but it doesn’t guarantee the valve will fit or control properly. Brand and model aren’t necessary for interchangeability—what matters is that the physical connections match and the control mechanism is appropriate. Operating temperature and pressure are important design limits, but they don’t alone establish a suitable replacement if the size and type aren’t correct.