How does a mechanical seal function?

• A. The spring pushes the seat against the seal and lubrication is maintained between the seal faces.
• B. It relies on a loose seal with no lubrication
• C. It uses a magnetic field to hold faces apart
• D. It uses a disposable cartridge

Answer: (A)

The key idea is that a mechanical seal uses two very smooth faces pressed together so fluid can’t leak between them, while a thin lubricating film forms between those faces. A spring or other biasing element pushes one face toward the other, maintaining contact and sealing even as the shaft moves and process pressure changes. The liquid being pumped between the faces provides lubrication and carries away heat, keeping friction low and the gap stable. This combination—faces pressed together by a spring and a lubricating film between them—is what makes the seal effective.

That’s why this description fits best: the spring ensures consistent contact and pressure, and lubrication is maintained between the faces. The idea of a loose seal with no lubrication wouldn’t endure wear or leak; a magnetic field isn’t how mechanical seals create a seal, and a disposable cartridge speaks to replacement design rather than the sealing mechanism itself.