Chilling Out with Sealless Pumps (Process Cooling & Equipment : September-October 2005)

Sealless pumps are used in many industries, most commonly to avoid the leak potential of rotating mechanical shaft seals. The term "sealless" is actually somewhat of a misnomer - while sealless pumps do not have a rotating shaft seal, they usually have at least a gasket or O-ring, often located between the two halves of the volute casing. Engineers typically do not use sealless pumps unless they have to because their physical size is usually larger than the conventional sealed pump models used in chillers, and their initial cost has been much higher historically. However, the overall cost of ownership of sealless pumps can potentially be low compared to pumps with mechanical seals, especially if a facility's downtime and maintenance costs are significant. The potential for leaks in a chiller system using sealed pumps commonly increases when extreme (cold or hot) fluid temperatures are involved, or rapid changes in temperature occur.