WK
Oil Quality : Machinery oil possessing good air release
properties and corrosion prevention characteristics; kinematic
viscosity 36 cSt approx. = 4.8
0
E at 50
0
C; flash point 150
0
C
minimum; pour point lower than -20
0
C.
Lubrication times : First oil change after the first 500 hours of
operation, subsequent oil changes after every 3000 hours of
operation approx., but at least once a year.
Fig. 11 Oil splash lubrication
Fig. 13 Constant level oiler viewed from X
Topping up of the oil fill at least once a month.
The bearing temperature may be allowed to rise up to 40
0
C
above room temperature, but should not exceed 80
0
C.
1.4.2 Grease Lubrication
(Cannot be provided on heavy duty bearing construction
pumps).
Portable (mobile) pumps, and pumps installed on board ship
have grease-lubricated bearings (See Fig. 14). Use a good
quality lithium soap ball and roller bearing grease, free of resin
and acid, and possessing rust preventive properties. The
grease should have a penetration number situated between 2
and 3, corresponding to a worked penetration situated between
2220 and 295 mm/10. Its drop point should be not less than
175
0
C.
The bearing temperature may be allowed to rise up to 40
0
C
above room temperature, but should not exceed 80
0
C. The
grease fill will last for 15000 hours of operation i.e., for 2 years
approx. If the operating conditions are arduous, the bearings
should be serviced once a year. A grease fill amounts to 10-20
grammes of grease, depending on the pump size. The pump
bearings are packed with grease at our Works before despatch.
1.5 Shaft Seal
The shaft is sealed at its exits through the casings by softpacked
stuffing boxes or by mechanical seals. If the pump is fitted with
special stuffing boxes, mechanical seals can be fitted in lieu of
soft packing (or vice versa) at any time during the service life
of the pump, with a minimum of machining of the cooling
compartment covers. On the other hand, the fitting of
mechanical seals to pumps equipped with standard or hot water
type soft-packed stuffing boxes necesitates the fitting of new
pump components. Particulars can be obtained from the pump
manufacturer.
1.5.1 Stuffing Boxes
Soft-packed stuffing boxes reduce the flow of leakage liquid at
the clearance gap between casing and shaft protection sleeve
when the pressure inside the pump is higher than atmospheric.
Conversely, on pumps which operate on suction lift, the soft-
packed stuffing box prevents the ingress of air into the pump.
Sealing is effected by means of soft packing (461.1) arranged
in a number of rings in the annular space between the stuffing
box housing (451) and the shaft protection sleeve (524.1/2)
and lightly compressed by the stuffing box gland (452).
Caution : On pumps which have a high discharge pressure,
the stuffing box at the discharge end is relieved of pressure,
via a balance liquid line, down to the suction pressure, provided
that the differential pressure across the pump exceeds 20 bar.
This ensures that the stuffing boxes at the suction and discharge
ends of the pump have the same admission pressure. This
arrangement applies to pump sizes 40 to 65 if the discharge
pressure exceeds 20 bar and to pump sizes 80 to 150 if the
discharge pressure exceeds 15 bar.
Single stage pumps require no special pressure relief even at
high discharge pressures. The pressure is relieved via the
balance holes in the impeller.
Overflow hole
Oil sump
Fig. 12 Construction with constant level oiler and sealing of
the bearing housing.
422.4
500.4
500.1 913 422.1
X
End side
(Heavy duty bring bracket)
Drive end
638
Fig. 14 Grease lubricated bearing construction
731.2 636
4
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