What device is used to prevent air from entering a pump due to insufficient packing tightness?

• A. Lantern ring
• B. Mechanical seal
• C. Throttle valve
• D. Check valve

Answer: (A)

The lantern ring is an important component in pump systems designed to prevent air from entering the pump when there is insufficient tightness in the packing material. Typically located around the shaft packing, the lantern ring provides a space for lubrication and helps maintain a seal. By allowing fluid to circulate through it, the lantern ring can help maintain proper pressure and prevent air from infiltrating, which could lead to issues such as cavitation and reduced operational efficiency.

This makes the lantern ring especially vital in processes where maintaining a fluid seal is essential for pump performance, as it enhances both sealing capability and longevity of the packing.