Question 313General Subjects - QMED

The correct answer is B) Double mechanical seal. A double mechanical seal is the most effective type of seal for pumps handling toxic or highly flammable liquids that cannot be permitted to escape into the atmosphere. Double mechanical seals have two separate sealing faces, creating a sealed chamber between them that can be pressurized or connected to a buffer fluid system. This design prevents any leakage of the pumped liquid to the atmosphere. The other options are not as suitable for this application. A conventional stuffing box (A) is a less effective seal that can allow some leakage. Rubber bellows mechanical seals (C) and external mechanical seals (D) also do not provide the same level of containment as a double mechanical seal for handling hazardous liquids.