The best packing for medium pressures and temperatures is ______

The best packing for medium pressures and temperatures is ______

• A. Aluminum
• B. Asbestos
• C. Plant Fiber
• D. Teflon

Answer: (B)

Packing material for a pump gland is chosen based on how hot and how much pressure the seal must handle. For medium pressures and temperatures, asbestos packing has historically been favored because its mineral fibers resist heat and maintain a stable, tight seal under compression. It doesn't soften or creep as readily as organic plant fiber at those temperatures, and it can withstand higher heat than plant fiber alone, making it reliable for moderate service. Aluminum isn’t used as packing since metal cannot form the necessary compressible seal in a gland and would wear quickly. Plant fiber packing, while useful at lower temperatures, loses strength and degrades under higher heat, reducing sealing effectiveness. Teflon offers excellent chemical resistance and low friction, but it can creep under medium pressures at higher temperatures, potentially compromising the seal over time. Modern practice avoids asbestos due to health concerns, but in this context its durability at medium temperatures and pressures explains why it’s chosen.

Packing material for a pump gland is chosen based on how hot and how much pressure the seal must handle. For medium pressures and temperatures, asbestos packing has historically been favored because its mineral fibers resist heat and maintain a stable, tight seal under compression. It doesn't soften or creep as readily as organic plant fiber at those temperatures, and it can withstand higher heat than plant fiber alone, making it reliable for moderate service. Aluminum isn’t used as packing since metal cannot form the necessary compressible seal in a gland and would wear quickly. Plant fiber packing, while useful at lower temperatures, loses strength and degrades under higher heat, reducing sealing effectiveness. Teflon offers excellent chemical resistance and low friction, but it can creep under medium pressures at higher temperatures, potentially compromising the seal over time. Modern practice avoids asbestos due to health concerns, but in this context its durability at medium temperatures and pressures explains why it’s chosen.