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between the rings of packing at the shaft. This void enables Anti-Keystone II Packing to consume up to 80% less power when compared to conventionally braided packings, according to the makers.
Originally, this modification to the trapezoidal cross section was intended to add mass to the outer half of the packing. This helps to prevent spinning of rings that are not seated fully during installation.
However, a significant side effect was discovered after the patent filing, in that the modified packing acted like a braided labyrinth seal. The voids remaining between the rings at the shaft sleeve provide a space for the fluid film to reside with added dwell time. Slowing the fluid's passage between shaft and packing has two advantages: l Pressure drops proportionally at each void, lowering the leakage rate. l Increased non-contact packing surface area raises the heat transfer rate through the packing, lowering the shaft sleeve temperature. Independent tests by a licensee indicate that: l At moderate pressures -approx 45 psi -an 80% reduction in power consumption is possible compared to conventionally braided packings of the same iibre and under the same conditions. l At high pressures -approx 264 psipower consumption is still reduced by 20% over conventionally braided packings.
The company says that as well as enhanced performance on rotating equipment such as pumps and agitators, the packing performs well in reciprocating services.
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