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DO NOT over-tighten the packing. Slight leakage is a necessary requirement for proper packing operation.
Leakage of five to ten drops per minute when the pump is operating is desirable, as it will preserve the packing
and avoid scoring of the shaft. Over-tight packing may score shafts, increase torque requirements of the pump,
damage couplings and drivers, and generate excessive heat.
The pump should be stopped and the packing gland adjusted whenever leakage exceeds ten drops per minute.
The condition of the packing should be checked at regular intervals, the frequency depending on the type of
service. Experience will dictate how frequently the inspections should be made.
MECHANICAL SEALS
Various types of mechanical seals are available to fit most pumps. (See VARIOUS SEALING ARRANGEMENTS
shown in Figure 15.3.) Due to the various seal types and styles available, the seal manufacturer's instructions for
installation and setting should be followed when available.
NOTE: Not all seals will fit or function in all pumps. Modification to the pump backplate, drive shaft, and/or
retainer may be required. Consult with a Roper distributor or Roper Pump Company if you are considering a seal
change in your pump.
For removal or installation of mechanical seals, refer to disassembly and assembly procedures for pumps.
CONVERSION FROM PACKED BOX TO MECHANICAL SEAL OR MECHANICAL SEAL TO PACKED BOX
Conversion kits are available to convert from a packed box pump to a mechanical seal pump or visa versa.
Contact your Roper distributor or Roper Pump Company for availability of conversion kits.
INSTALLATION OF A POSITIVE DRIVE SEAL (JOHN CRANE TYPE 8-1 AND TYPE 9)
Refer to the exploded parts drawing shown in Figure 15.1 and to the appropriate seal chamber dimensional
drawing shown in Figure 15.2.
1. Machine a counterbore at entrance to seal chamber of backplate (6A, B) as shown in dimensional drawing
in Figure 15.2.
2. With drive shaft (32) out of pump, install retaining ring (12) on drive shaft to locate mechanical seal.
3. Carefully remove all burrs and sharp edges on the shaft over which rotating element of seal will slide.
4. Apply a lubricant to seal I.D. and to drive shaft O.D. that is compatible with product being pumped and
elastomers within pump. DO NOT use petroleum base products with seals with EPR elastomers. Clean
and lubricate parts with light oil unless EPR elastomers are used. Use a nonpetroleum base lubricant with
EPR elastomers.
5. Slide rotating element of mechanical seal onto drive shaft before removing three or four clips that are
taped to rotating element. Push it back to retaining ring (12), tighten setscrews in seal, and remove clips
that are taped to seal.
6. Slide faceplate end of drive shaft, with mechanical seal attached, into backplate (6A, B) through bore for
outboard ball bearing (2).
7. Use a compatible lubricant to lubricate o-ring on stationary seal face and seal chamber bore.
8. Slide stationary seal face over keyway end of drive shaft (32) and down to seal chamber. Be sure lapped
(polished) face is toward rotating member of seal.
9. Install outboard ball bearing (2) to position drive shaft (32) as shown in appropriate sectional drawing in
Figure 14.2.
10. Push stationary seal face into seal chamber.
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