Stuffing Box Seals

Gage glasses including gage cocks Liquid sealed stuffing box for shaft of agitators, pumps, etc. (per in. shaft diameter)... 

Stuffing Box. Stuffing box shall he suitable for packing, single (inside or outside) or double-inside mechanical seal without modifications. Stuffing box shall he accurately centered by machined rabbit fits on case and frame adapter. 

Stuffing Box with Mechanical Seal. Mechanical seal shall he of the (single inside) (single outside) (double inside) (cartridge) type and (balanced) (unbalanced). 

Luhtication—Stuffing Box with Mechanical Seals. Suitable tapped connections shall he provided to effectively lubricate, cool, flush, quench, etc., as required by the application or recommendations of the mechanical seal manufacturer. 

Pre.s.sure. Pressure affects the choice of material and whether balanced or unbalanced seal design can be used. Most unbalanced seals are good up to 100 psig stuffing box pressure. Over 100 psig, balanced seals should be used. 

External seals (Fig. 10-115) are installed with all seal components protected from the process fluid. The advantages of this arrangement are that (1) fewer critical materials of construction are required, (2) installation and setting are somewhat simpler because of the exposed position of the parts, and (3) stuffing-box size is not a hmiting factor. Hydraulic balancing is accomphshed by proper proportioning of the seal face and secondary seal diameters. 

Throttle bushings (Fig. 10-117) are commonly used with single internal or external seals when sohds are present in the fluid and the inflow of a flushing fluid is not objectionable. These close-clearance bushings are intended to serve as flow restric tions through which the maintenance of a small inward flow of flushing fluid prevents the entrance of a process fluid into the stuffing box. 

This is the pressure measured in the stuffing box or seal chamber. This is the pressure to be sealed by the mechanical seal or packing. The seal chamber pressure must be within the limits of the mechanical seal. This... 

The shaft under the restriction bushing at the bottom of the stuffing box or seal chamber. 

If the serviee happens to be below atmospherie pressure, then speeial eonsiderations are required to seal the material effeetively. Most unbalaneed seal designs are applieable up to 100 psig (7 Bar) stuffing-box pressure. At more than 100 psig (7 Bar), balaneed seals should be used. 

Part Purpose Shaft sleeve Protects the shaft where it passes through the stuffing box. Usually used in pumps with packing but often eliminated if mechanical seals are employed. 

MODIFIED STUFFING BOX. .. available with Jahn Crane Type I mechanical tealt. These mechanical seals are easy ta install in the field and are carried in stack. 

Figure 3-18 illustrates a seal installed in a conventional stuffing box with cooling liquid flow path. Figures 3-18, 3-19A, 3-19B, 3-20 and 3-21 identify the fundamentals of mechanical seals, even though there are many specific designs and details. These various designs are attempts to correct operational problems or seal weaknesses when... 

Figure 3-18. Typical single mechanical seal inside pump stuffing box. (Courtesy Borg-Warner Co.)...

Suction Pressure Dead-ended in Stuffing Box.No Circulation From Discharge or Internal Seal Passage. 

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