(8) improper packing or over service life, causing aging, cracking or loss of elasticity.If the packing rope itself loses its elasticity, it is difficult to undergo radial deformation when it is being squeezed by the packing gland and cannot fill the gap between the pump shaft (stem) and the inner wall of the packing cylinder.
(9) the radial fit gap between the packing cylinder and the gland cylinder is too large.When the packing gland is not matched with the packing cylinder and the thickness of the gland cylinder is smaller than the width of the packing chamber, the packing is limited by the squeeze action of the gland and cannot produce sufficient radial deformation.This condition is commonly seen in packing seals at some older valve stems, but is often not easy to spot.
(10) damaged surface (corrosion, wear, surface scratch or broken thread of stem, etc.) of packing cylinder inner wall or pump shaft (stem).
(11) the pump shaft (valve stem) is bent.Pump shaft (stem) wear, bending or eccentricity is a major cause of leakage.
(12) if the filler is too hard or contains granular impurities, long-term operation will cause wear and tear of the shaft.Tests have shown that the asbestos packing has the worst wear on the shaft (stem).
(13) the actual pump head is too high.Generally, for the same centrifugal pump, if the speed is fixed, when the flow rate decreases, it increases
Cheng.Once the pressure of the internal media increases, it may break the original packing seal and form leakage.
(14) packing wear is serious.The packing wear of normal loading is more uniform, larger near the gland and smaller inward.If the packing is not good enough, there will be great wear near the gland in a short time, but no wear at the depth of the packing.
(15) the filler takes too long to use.During the operation of packing, it is susceptible to wear, erosion, aging, dryness, temperature and other factors, and gradually loses its compactness and leads to leakage. This phenomenon is relatively common in packing sealing device.