The make-up valve is described as which of the following?

• A. Spring-loaded, diaphragm-operated valve that closes with steam pressure
• B. Electrically actuated globe valve
• C. Manual globe valve
• D. Ball valve with pneumatic actuation

Answer: (A)

The make-up valve is a spring-loaded, diaphragm-operated valve that closes with steam pressure. In this design, the diaphragm senses steam pressure and, as pressure rises, it is pushed to shut the valve against the spring. When steam pressure drops, the spring pushes the diaphragm back, opening the valve to admit makeup water. This arrangement provides auto control: makeup flows when steam isn’t up, and is automatically stopped when the boiler is firing.

Other types (electrically actuated globe, manual globe, or ball valve with pneumatic actuation) wouldn’t inherently respond to steam pressure in this automatic way, so they aren’t described for this function.