COLUMN
9.00E-03 8.00E-03 7.00E-03 6.00E-03 5.00E-03 4.00E-03 3.00E-03 2.00E-03 1.00E-03
Final meassurement mbar l / s vs seating torque
Y = 2E-05x 2 - 0.0012x + 0.0228 R 2 = 1
Pre-deformation : 20 Nm x 2 Working load : 30 Nm Measurement : 6.3 10 -3 mbar l / s
Pre-deformation : 40 Nm x 2 Working load : 30 Nm Measurement : 3.9 10 -3 mbar l / s
Pre-deformation : 50 Nm x 2 Working load : 30 Nm Measurement : 8.0 10 -3 mbar l / s
0.00E + 00
0 10 20 30 40 50 60
Figure 3 . Carbon packing test
with three different seating torque values is accurately represented by an equation that reaches an optimum sealing value with a particular seating torque value , providing the lowest emissions . With higher torque values , sealability starts to decrease . In all cases , sealability initially improves with an increase in seating torque value until the optimum value is reached . This is clearly represented in the carbon fibre packing which , due to its composition , has a lower ability to seal , and changes in this ability are clearer . If the optimum seating torque value is exceeded , the packing set loses some of its sealability . This must be due to over-compression , which lowers the packing set ’ s ability to adapt to the irregularities in the stuffing box due to increased stiffness . These tests show that , once we know the optimum torque value for the packing set at the working conditions , an initial deformation or an optimal seating torque value before operation could : ( a ) improve the packing set behaviour during operation and , ( b ) minimise some irregularities both in the packing and in the stuffing box , generating more homogeneity and better performance of the packing set . The author would like to thank Babcock Valves for performing the tests and providing photographs .
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