Which of the following statements represents the main difference between a stuffing box gland and a mechanical seal for sealing the shaft of a centrifugal pump? |
A) Packed stuffing box glands are subject to wear, but mechanical seals are not. |
B) Packed stuffing box glands must be cooled by the liquid being pumped, but mechanical seals do not require cooling. |
C) If packing fails, the pump can be kept running temporarily by tightening the gland, but if a mechanical seal fails it must be totally renewed to stop the leakage. |
D) The sealing surface of a mechanical seal is parallel to the shaft, but the sealing surface of a packed gland is perpendicular to the shaft. |