What is the purpose of a diaphragm in a compressor?

• A. It increases surface area so that gas slows down and pressure goes up
• B. It seals the system against leaks
• C. It cools the gas during compression
• D. It reduces the mass flow rate

Answer: (A)

In a diaphragm compressor, the diaphragm acts as the moving boundary that pushes on the gas to produce compression. By presenting a large, flexible surface for the gas to act against, the gas flow is spread out and slowed as it moves past the diaphragm. That deceleration converts some of the gas’s kinetic energy into pressure energy, raising the static pressure and achieving the compression needed for charging the downstream system. This surface-area interaction is the main reason the diaphragm is effective in increasing pressure during compression. Cooling the gas, sealing the system, or reducing mass flow rate are not the primary roles of the diaphragm itself.