Mechanical seal mounting assembly for a centrifugal
A stationary seal ring adapter is secured to a first end of a seal carrier which extends through the pump's back plate. A split gland ring is attached to a second end of the seal carrier and is supported by gland nuts threadedly carried on gland bolts. The gland bolts are attached to a bearing assembly for the pump shaft. Axial movement of the pump shaft to effect impeller clearance seal adjustment is possible without disturbing the mechanical seal adjustment. An O-ring is interposed between the pump back plate and the seal carrier and is held in place by an O-ring retainer secured to the back plate of the pump.
More particularly, the present invention is directed to a mechanical seal mounting assembly for a slurry pump. Most specifically, the present invention isdirected to a mechanical face type seal mounting assembly for use with high solids concentration slurry pumps. A mechanical seal assembly is installed in a pump whose impeller seal clearance is adjusted by axial displacement of the pump shaft.
The mechanical seal's stationary assembly is carried by a seal carrier which passes through the back plate of the pump. An O-ring is held by a retainer about the seal carrier to prevent static leakage while still allowing axial movement of the seal carrierand stationary seal assembly. A split gland assembly supports the seal carrier and facilitates its attachment to the pump shaft bearing assembly through an adjusting gland bolt. Seal adjustment is possible during pump operation and seal replacement issimplified.
As will be set forth in greater detail in the description of the preferred embodiment, the seal mounting assembly in accordance with the present invention is intended for use in securing a seal such as a rubber in shear seal, a type of which isdisclosed in the previously noted Wentworth patent, to a centrifugal slurry pump. The rotating seal ring adapter is secured to the impeller shaft and the stationary seal ring adapter is secured to a seal carrier which passes rearwardly through thepump's back plate. A split gland ring attaches to the seal carrier and is, in turn, secured to the pump's bearing assembly. The split gland ring can be moved axially by gland bolts to effect mechanical face seal adjustment. An O-ring assemblysurrounds the seal carrier and prevents leakage of any of the pumped fluid.
The axially adjustable pump shaft can be moved to adjust pump impeller seal clearance without affecting the setting of the mechanical seal assembly. The seal carrier is attached to the bearing housing and the rotating seal ring to the impellershaft. The shaft is connected to the bearing housing through bearings which require axial clearance. Therefore, relative motion exists between the shaft and bearing housing which will affect seal setting as required by bearing clearances.
Adjustment of the face seal assembly can be made during pump operation. As an abrasive slurry is being pumped and causes seal face wear, the seal faces can be moved toward each other by adjustment of the split gland ring through the gland bolt. Precise seal adjustment can be made for each pumping application, thereby eliminating the detrimental effects of added preload forces which will previously have been used to compensate for unknown operating conditions.
Complete pump overhaul is thus necessary only when the pump shaft bearings fail and notwhen the mechanical seal assembly wears out. If a bearing assembly does fail, it can be removed and replaced by a spare assembly that has been assembled in a clean shop environment and includes the mechanical face seal and mounting assembly of thepresent invention. The cartridge-type bearing assembly, together with the mechanical rotary seal carried by the mounting assembly of the present invention, can be installed by a mechanic in a single operation. This is a particularly beneficial featureespecially when bearings fail at times or in locations where experienced mechanics are not readily available. The failed bearing and seal can be removed as a unit and replaced with a new bearing and seal unit which does not need extensive fieldadjustment.
Should there be leakage of the pumped fluid between the seal carrier and stationary pump back plate, a stationary O-ring assembly is carried by the seal carrier intermediate its ends. This O-ring can be removed, cleaned, and replaced withoutremoving the seal. The seal carrier can slide with respect to the O-ring during mechanical seal or impeller seal adjustment.
The slurry pump mechanical seal mounting assembly in accordance with the present invention is useable with numerous pump assemblies and facilitates the mounting and usage of a mechanical seal.