Installation and Operation
The right kind of installation can make considerable difference to the service obtained from a centrifugal pump. A poor design of the suction will cause reduced capacity, and may result in cavitation in the fluid end of the pump. Cavitation can reduce the pump's service life considerably. For pumps handling salt water, a positive suction head is particularly desired, to prevent corrosive gases from coming out of the fluid at the impeller eve.
LOCATION: Locate the pump as close to the liquid supply as practical so that the suction lift will be low and as short and direct as possible the pump should be accessible for inspection and maintenance.
BASE: The base of the pumping unit must be adequately supported on a flat surface in order to maintain proper alignment of pump and motor and to guard against shifting support which could cause line strains.
SUCTION PIPING: The suction piping should never be less than the size of the suction flange. It is recommended that the suction piping be at least one inch larger than the suction flange whenever possible. The suction line should have a straight run going into the pump of a minimum length of two times its diameter. Air pockets in the suction piping should be eliminated by sloping the line downwards to the source of supply and using an eccentric reducer at the suction flange. Bends or elbows should have long radius to minimize friction lost. A flooded suction will require a butterfly valve installed in the line to permit closing of the line for inspection and maintenance. A lift suction will require a foot valve for priming where a vaccum pump is not used All piping should be independently supported and accurately aligned and. preferably, connected to the pump by non- collapsing flexible piping to eliminate Iine strains.
DISCHARGE PIPING: A pressure gauge and butterfly valve should be installed In the discharge line. The butterfly valve is required for regulating the flow capacity and discharge pressure and to isolate the pump from the discharge fluid for inspection and maintenance. All piping should be independently supported to eliminate line strain and misalignment.
COUPLING ALIGNMENT: Good service life of the pump, driver, and drive coupling depends upon good align. ment through the flexible drive coupling. Poor alignment may cause failure of the pump and motor bearings or of either shaft. After the piping has been connected, the pump unit must be rechecked for proper alignment of the pump shaft and motor shaft through the coupling. The recommended procedure for coupling alignment is by the use of a dial indicator. Information regarding the tolerance in alignment for couplings is usually supplied by the coupling manufacturer.
ROTATION: The direction of rotation of pump and driver should be checked. They should rotate In the same direction.
NOTE: Never adjust the pump's capacity by throttling the suction line.
Start-Up and Operation
BEARING LUBRICATION: See that the oil chamber is filled to the correct oil level as indicated by the oil dip stick. use any good brand sae 30 wt. non-detergent automotive type Oil. Do not overfill.
STUFFING BOX PACKING: At start-up with new packing in the stuffing bog, the gland bolts should be only finger tight. After fifteen to twenty minutes of operation, tighten the gland bolts slowly until the stuffing box drips about six to ten drops per minute. The packing should be greased about every four hours.
PRIMING: Vent air from suction line and pump housing to allow them to fill completely with fluid while priming. For pumps with a flooded suction, slightly open the discharge valve and fully open the suction valve. This will allow the pump and suction line to fill completely.
START-UP; Start the pump with the discharge valve about one third open. After the discharge pressure stabilizes, gradually open the discharge valve to the required position.