OPERATION & MAINTENANCE

INSTRUCTIONS - Top

The information contained herein is of a general character and will be supplemented upon requested by specific instructions applying to the particular type of rotary pump being operated. It is requested that these instructions be placed in the hands of those directly charged with the installation and operation of the equipment. Satisfactory service can be realized only upon strict adherence of these instructions

CHECKING EQUIPMENT - Top

Inspect and check shipping manifest immediately on receipt of shipment and report any damage or shortage to the company. 

LOCATION - Top

The pumps should be installed in alight, clean, dry location and so place that it is easily accessible for inspection. Suction piping should be full size, short and direct. Motor driven units should not be located in damp or moist places unless provision has been made for this condition.

FOUNDATION - Top

The foundation should afford permanent rigid supported for the entire unit.
Concrete foundation built up from solid ground will prove most satisfactory. Ample allowance should be provided for grout in building the foundation.
Foundation bolts of the specified size should be accurately located according to drawings when the concrete is poured.
When a unit is mounted on steel work or other structure, it should be set directly over, or as close as possible to the supporting beams or walls, and should  be so supported that the base plate cannot be distorted by yielding or springing of the structure.

ERECTION  - Top

Alignment - Top

Correct alignment is absolutely essential for successful operation. A flexible coupling will not compensate for slight changes in alignments which may occur during normal operation.

Factory alignment - Top

Every unit assembled at work is accurately aligned by placing the base plate on surface plate and then leveling the machined pads. Shims are inserted under the feet of the pump and driver when necessary to obtain perfect alignment. However, all base plates are elastics and for this reason we cannot assume responsibility for the proper mechanical operation of a unity unless the shop alignment is reproduced when the unit is erected on its foundation.

Field alignment  - Top

Pumps are usually shipped on their base plates and it is seldom necessary to remove the pump and driver from the base plate while leveling. The pumping unit should be placed on the foundation supported by wedges place near the foundation  bolts. Remove the paint from the projections of the base plate pads upon which the pump feet are supported. Place a spirit level on these pads and adjust the wedges under the base plate to boring the pump to the shaft level.

The alignment is then to be checked and corrected so as to bring the driver half coupling in perfect alignment with the pump half coupling. The checking of alignment can be accomplished by the use of a straight-edge across the top and sides of the coupling.

If the coupling’s flanges are not perfectly true or not of the same diameter, check the alignment by revolving coupling and checking at each quarter turn. If any variation is found, proper allowance must be made in alignment the unit. The clearances between the coupling halves should be set so that they cannot strike, rub or exert end thrust on either pump or driver.

Important - Top

Alignment must be checked after the pump has been completely piped up because pumps are frequently sprung and pulled out of position by drawing up flange bolts when the flanges are not squired up before tightening .Particular care must be taken that the suction and discharge piping is properly supported to prevent a strain or pull on the pump. Pipe strain are a common cause of misalignment, hot bearings, wear and vibration.

Grouting - Top

The base plate should be grouted in before the piping connections are made. The usual mixture for grout is : one part cement and two parts sand with sufficient water cause the mixture to flow freely. The grout should be worked in under the base plate so as to support it fully throughout its whole area.

SUCTION PIPING - Top

Experience has proved that a faulty suction line is responsible for trouble with rotary pumps. Suction piping should never be less diameter than the full size of the pumps suction opening. It should be as short and direct as possible and thoroughly clean. It should be uniformly graded up form the source of the supply to the pump. When drawing liquid over long distances or on high suction lifts or when handling thick, viscous liquids, the diameter of the suction pipe should be greater then the opening in the pump to convey the liquid with minimum pipe friction loss.

Rotary pumps have excellent suction qualities but cannot be expected to do the impossible. Remember that atmospheric pressure (14.71 1bs.Per sq .inch absolute) is shall that forces liquid into a pump. If the static suction lift plus suction pipe friction is equal to or greater than the equivalent of atmospheric pressure, the pump will not fill, resulting or entire loss of capacity.
When pumping highly volatile liquid such as butane, propane, hot oils, etc. there must be sufficient static head on the suction in addition to the vapour pressure to prevent vaporization of the liquid within the pump. Rapid wear or Brazing will result if these pumps are allowed to run dry.

The suction line should be perfectly air-tight. A leak will result in reduced or entire loss of capacity. A strainer is recommended if the liquid contains foreign material. Abrasives in the liquid will cause rapid wear. The strainer should have a net area of from three to four times the suction pipe area and should permit easy cleaning. Always carry the discharge up through a riser approximately five times the diameter. This prevents gas or air pockets in the pump and will act as a seal high vacuum service. A valve on the top of the riser may be used as a vent when starting the pump. To protect the pump against excessive pressures caused by increased pipe friction in cold weather or accidental closing of valve should be set slightly higher than maximum pump discharge pressure but not more then 10%

STUFFING BOXES - Top

Normally pumps are provided with neoprene rubber oil seals.
When gland packing is provided, do not tighten the glands too tightly as a slight leakage will help to lubricate the packing.

PRIMINGG - Top

Before starting up for first time, prime up the wet gears for effective suction.
These pumps are run and tested on oil. Unless specified on the order, the oil is left pump to protect the internal mechanism against corrosion. if this oil is detrimental to the system, it will be necessary to detrimental to the pump, clean all parts thoroughly and fill the pump with the liquid to be pumped.
Never start or run the pump dry. This will invariable cause galling, seizing or destructive wear between the rotors, end plates and casing.

DIRECTION OF ROTATION - Top

Direction of rotation is marked with an arrow on the pump.
When the direction of rotation is to be reversed, fix the back cover after rotating the same 180 angle. The bolts should be secured tight in the original position so that there is no leakage.

STARTING AND OPERATING  THE PUMP - Top

Before starting prime the pump and then check the prime mover for correct rotation. Check pressure or vacuum on the inlet and outlet  side to be sure that the pump will deliver full capacity without overloading the driver.
It is advisable to start operation at a reduced load gradually increasing to maximum service condition.
External bearing pumps require occasional lubrication of soft grease in the bearing. If no grease fittings are furnished on internal bearing pump, no attention for lubrication is necessary.

MAINTENANCE - Top

PERIODICALLY - Top

1. Alignment of the pump and motor should be checked.
2. Suction line should be checked for no air leakage and jamming of the dirt in filter.
3. If there is a pressure drop, the relief valve should be further screwed in till desired pressure is achieved. If  this does not give any result,  then there should be a considerate wear in the plates, which should be   replaced.
4. Leakage, if any, on end covers should be eliminated by tightening bolts.
   

YEARLY - Top

1. If a pressure drop is too much, the gears or the wear plates should be changed as the case may be due to excess wear on them.
2. Oil seal should be replaced if there is leakage from the drive end.
3. On dismantling, if the body shows wear, then it should be sent back to us for placement. This will be a very long run only.
4. Bearings, if found worn out, should be replaced.
   

IMPORTANT - Top

1. If the pump gets jammed in running position, then loosen all the bolts by half a turn (this will also be in the case of pumps with bush bearings) and try to rotate the pump shaft with pipe spanner. if it rotate then start pump and allow it to run smoothly and lighten the bolts slowly till there is no jamming.
2. if the rotor does not rotate, then dismantling is necessary.
3. Where the pump is excessively heated in the initial running, and jamming is caused, allow it to cool down to the temperature till the jamming is eliminated.
4. At the time of commissioning, under no circumstance the pump should be dismantled due to any fault whatsoever without consulting the manufacturers.
5. At the commissioning stage, if the shaft is found tight, try to rotate the shaft with the help of pipe wrench. if it rotates with the pipe wrench, then tightness should be considered as normal and the pump can be started without any trouble.
   

DISMANTLING AND REASSEMBLY OF  "ALFA" ROTARY GEAR PUMPS - Top

(a) PUMPS FITTED WITH BUSH BEARINGS: - Top

1. Unbolt side covers and push out assembly of rotors and bushes making note of packing on either side.
2. Slide out the bushes form shafts and check for face wear. If excessive wear is there, replace them and If minor wear is there, have a fine machine cut on the face such that both bushes on either side are exactly of same width.
3. Number of packing should be reduced corresponding to the reduction in bush width but minimum one packing should be there on either side.
4. Remove all the burrs in body bore, on body faces as well as on rotors. Insert the rotors first in the body and then fit the bushes on either end and check for free rotation.
5. If seal is damaged, take out circlip and seal, replace with new seal and fit back in the cover.
6. Put appropriate packing with grease taking care that there is no overlapping on bush faces and then fit the covers with bolts.
7. Free rotating  of the shaft should be checked with a small pipe wrench. if shaft is found tight, loosen cover bolts by quarter turn and start the pump. When it runs smoothly tighten the bolts equally and slowly. if seizure occurs, add one more packing.
8. In case of any ovality found in bush bore, it should be replaced.
9. If excessive wear is found on gear teeth, complete set is to be replaced.
10. Pumps are fitted with 'O' rings. In case of any wear on bush face in pumps, it should be replace
11. Minor scoring in body bore will not affect pumps' performance to great extent but if heavy scoring is found, body should be replaced.
    

(b) PUMPS FITTED WITH ANTIFRICTION BEARINGS: - Top

1. Unbolt both side covers making note of packing on either side.
2. Heavier pumps are provided with jacking arrangement to take out covers. Threaded holes are provided on covers. Insert suitable bolts and jack up the cover.
3. Push out the assembly of rotors, wear plates and bearings such that wear plates  of opposite side come out of the body, By means of pullers, take out the bearings and wear plates and push the remaining assembly out in the opposite direction. Take out the bearing and  wear plates from the other side also by means of pullers.
4. Check the wear on wear plates. if excessive wear is there, replace the complete set of wear plates. In case of minor wear ,  take a fine machine cut on the face such  that the width of top and bottom wear plates is equal.
5. Check the wear on gears and shaft. If minor wear is observed on face of gears grind the faces (in case of hardened of hardened  gears) or take a fine machine on the face of soft gears such that driver and driver gears match perfectly well with the same face width. Remove all burrs from body bore, body face as well as on rotors and wear plates.
6. Insert the rotors first in the body and then wear plates on both sides. Now fit the bearings in each wear plate. Keep a watch on free rotation of shaft with the help of a pipes wrench.
7. Reduce the packing corresponding to the reduction in width of wear plates and gears. Place the packing on body face with grease such that there is no overlapping on wear plates.
8. If seals are damaged, take out circlip and seals and fit new seals in the cover.
9. Now fit front and back covers and bolt them. if dowel pins are provided covers should be first located with dowel pins and then they should be bolted.
10. In case of excessive scoring in pump body, it should be replaced.
11. If pump is not rotating freely, loosen cover bolts slightly. Now start the pump and let it run for some time, then tighten all bolts equally. In case of seizure and one more packing.
12. If the pumps is having steam jacket, then before taking out cover remove jacket coupling and plugs from both covers.

"ALFA" ROTARY GEARS PUMPS SPARE PARTS LIST - Top

(A) RECOMMENDED SPARE PARTS FOR NORMAL OPERATION OF GEAR PUMPS - Top

(B) RECOMMENDED ADDITIONAL SPARE PARTS - Top

(C) SPECIAL INSTRUCTIONS - Top

1. In case of pumps provided with Mech/seal instead of oil seals, procure 1 no. Mech/seal
   

(D) IMPORTANT- Top

1. While floating your enquiries for spares of "ALFA" Rotary Gear Pumps, please furnish the following details:
2. Nameplate details / Pumps Serial Number.
3. Purchase order number and data

GEAR PUMP FAULT FINDING CHART - Top

PUMP FITTED WITH ANTIFRICTION BEARINGS  - Top

PUMP FITTED WITH ANTIFRICTION BEARINGS  - Top