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Maintaining Irrigation Pumps, Motors, and Engines


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Maintaining Irrigation Pumps, Motors, and Engines

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  • 1. Maintaining Irrigation ATTRA Pumps, Motors, and Engines A Publication of ATTRA - National Sustainable Agriculture Information Service • 1-800-346-9140 • www.attra.ncat.orgBy Mike Morris and This publication explains how to maintain irrigation pumps, motors, and engines for peak efficiency.Vicki Lynne The publication includes descriptions and diagrams of recommended installations, checklists for main-NCAT Energy tenance tasks, and a troubleshooting guide. Each system component is treated separately and main-Specialists tenance tasks are broken down by how frequently they need to be done. References and resource list-© 2006 NCAT ings follow the narrative.Contents IntroductionIntroduction ..................... 1 Efficient irrigation begins with properlyRecommended installed and maintained pumps, motors,Installations ...................... 1 Centrifugal Pump ....... 1 and engines. Turbine Pump .............. 2 Equipment problems and management Control Panel ............... 2 problems tend to go hand in hand. Equip-Pumping Plant ment that is badly designed or poorlyMaintenance .................... 3 Electric Motors ............ 3 maintained reduces the irrigator’s degree Control Panel ............... 5 of control over the way water is applied. Engines .......................... 6 Problems like patchy water distribution Centrifugal Pumps ..... 8 and inadequate pressure make it impos- Turbine Pumps .......... 12 sible to maintain correct soil moisture lev-Troubleshooting ........... 13 els, leading to crop stress, reduced yields,References ...................... 15 wasted water, runoff, soil erosion, and many other problems. NCAT photo Recommended Installations the pumping plant might look like Fig. 1, Centrifugal Pumping Plant Poor, on the discharge side. The next time Installation with Electric Motor you rebuild the pump, replace the fittings so The term “pumping plant” refers to the irri- that your system will look like Fig. 1, Ideal. gation pump and motor or engine, consid- An ideal installation should also have: ered together. If you have an older system, A discharge concentric expansion Figure 1. Ideal and Poor Installations instead of an abrupt change in pipe IDEAL Discharge pressure diameter, to minimize head loss, Concentric expansion Shut-off valve gauge with ball valve Discharge pipe turbulence, and air pockets. larger than pump discharge size A discharge valve the same diam-ATTRA—National Sustainable eter as the mainline.Agriculture Information Serviceis managed by the National Cen- Check Flexible joint permits some misalignment and axial Pipe support Fig. 2 shows what your pumping plantter for Appropriate Technology valve movement; resolves most thermal expansion problems should look like when pumping from a(NCAT) and is funded under agrant from the United States POOR Valve too small surface source such as a river or canal.Department of Agriculture’s The pumping plant should also have:Rural Business-Cooperative Ser-vice. Visit the NCAT Web site( Sudden On the Suction Side of Pump: expansionhtml) for more informa-tion on our sustainable (Adapted from Saving Energy on Montana Farms and Ranches, A well designed and screened sumpagriculture projects. Montana Department of Environmental Quality.) that keeps trash away.
  • 2. Suction line joints that are airtight On the Discharge Side of Pump: under a vacuum. A valve size that is the same diam- No high spots where air can collect. eter as the mainline.Related ATTRAPublications A suction line water velocity of five A non-slam check valve to pre- feet per second (fps) or less; two to vent back spin when shutting offEnergy Saving Tips forIrrigators three fps is best. the pump.The Montana A suction entrance at least two pipe An air relief device when a buried bell diameters from sump inlet.Irrigator’s Pocket mainline is used.Guide A suction lift (vertical distance from A discharge line water velocity ofDrought Resistant Soil water surface to pump impeller) less than 15 to 20 feet. less than seven fps. Five fps is best.Drought ResourceGuide An eccentric reducer to keep air An energy efficient 1800 rpm motorSoil Moisture from becoming trapped in the with a 15 percent safety factor.Monitoring: Low-Cost reducer fitting. A simple shade over the motor.Tools and Methods A vacuum gauge to indicate whetherMeasuring and the primer is pulling a vacuum or Turbine Pump InstallationConserving IrrigationWater just moving air through the pump. Refer to the left half of Fig. 3 for a prop- erly installed turbine pump in a well; many of these same principles apply to turbineFigure 2. Recommended Pump Installations, Top and Side Views pumps in sumps. The properly constructed well should also: Top View Be at least six inches in diameterSolid Gradually increasing larger than the outside diameter of tapered sectionfoundation the well casing when a gravel pack Sump volume at least twice maximum gpm is required. Inlet All joints Have horizontal well screen slotsCone increaser water tight Uniformly distributed flow that continue below the pumpingplaced at pump Pressureoutlet if required gauge o 45 maximum water level. The openings should Supports as hold back at least 85 percent of theStraight run of at least10 pipe diameters “D”or straightening vanes required surrounding material.for testing flow The poorly constructed well in the lower Check valve right half of Fig. 3 shows a well casing that Shut-off valve is not centered in the well. Vertical slotted pipe perforations are above the minimum Primer Straightening vanes or Side View water level, creating cascading water. straight run as short as possible but not less than Globe 6 pipe diameters “D” isolation valve Vacuum gauge 1/4” per foot minimum upward Grating, bar racks Control Panel for Electric Motors slope to pump and screens at beginning of The importance of a properly installed Smooth long-radius maximum width section control panel cannot be overemphasized elbows for personal safety and for protecting your investment in your pump and motor. Minimum water Your control panel should: Anchor Pipe supports “D” (as required) level Drainage bolts Eccentric 4 “D” Minimum inlet Inlet away from reducer minimum motor Suction bell turbulence Have a shade over it to keep As close as Inlet below minimum “D” = pipe thermal breakers cool. “D” minimum water level diameter possible Be mounted on secure poles (Adapted from Energy Efficient Pumping Standards, Utah Power & Light Company.) or foundation.Page 2 ATTRA Maintaining Irrigation Pumps, Motors, and Engines
  • 3. Figure 3. Deep Well Turbine Pump Pump motor RECOMMENDED Sounding tube Discharge pipe access Grout seal Casing centered in hole with 3 spacers @ 40’ intervals Pumping water level Static water levelDrawdown less NCAT photothan 60% of waterdepth Pump housing Pumping Plant Maintenance Air line Every irrigation system needs regular maintenance in order to run effi ciently and reliably. Poorly maintained systems waste energy and money, and are prone to breakdowns that cause crop losses and Excess pumping rate; drawdown more than yield reductions. 60% of water depth NOT RECOMMENDED Caution: The recommendations below are not comprehensive and(Adapted from Energy Efficient Pumping Standards, UtahPower & Light Company.) may not be correct for all systems. Consult your owner’s manual for rec- ommended maintenance procedures and always follow the manufactur- Have any missing knockout plugs er’s instructions if they differ from the and other holes in the starting switch ones in this guidebook. box replaced and screened or puttied against rodents, insects, and dirt. Electric Motor Maintenance Have a small hole (3/16-inch diam- eter) in the bottom of the panel to General allow moisture to drain. Make a habit of checking that the motor isYour control panel should include the securely bolted to its platform. Mountingfollowing controls at a minimum: bolts can vibrate loose. Check to see that rotating parts aren’t rubbing on station- Circuit breaker(s) for overload currents. ary parts of the motor, causing damage to Lightning arrester. the motor. Surge protector. Remember that an electric motor is an air-cooled piece of equipment and needs Phase failure relay, to protect the all the ventilation it can get. Excessive motor from phase reversal or failure heat is a main cause of reduced motor life. and from low voltage. Motors also like to be dry. Keep motor A pressure switch to shut off the windings dry by keeping pump packing motor if pumping pressure drops to in good condition. Even if windings are undesirable levels. protected from moisture, minerals in ATTRA Page 3
  • 4. pumped water can attach arcing at electrical terminals. The voltage to the windings and cause drop across loose connections will cause early failure. the motor to operate at less than its rated voltage, increasing internal motor tempera- Motors that operate at ture. Increased heat will break down motor 3600 rpm experience twice winding insulation, resulting in electrical as much wear as motors shorts and motor failures. A loose or bro- operating at 1800 rpm. ken connection can also unbalance the Regular maintenance is phases of three-phase power and damage especially critical for 3600 the motor windings. rpm motors and pumps.NCAT photo Caution: Before conducting these Maintenance Tasks tasks, be sure power is off at the util- At season startup: ity disconnect switch. It may be neces- sary to have the utility company shut Remove tape on all openings the power off. and clean out rodents, insects, or debris. Maintenance Tasks Locate the motor drain hole on At season startup: the base or support for the base, and clean it out so water won’t be Inspect insulation of motor wind- trapped and held directly under the ings. If the windings are excessively air intake. grease-covered, consult your motor repair shop for direction. Change oil in reduced voltage start- ers, using an oil recommended by Check all safety switches according the manufacturer. Be sure to clean to the manufacturer’s directions. the oil pan before refi lling. Twice a year: Use vacuum suction or air pressure Check electrical connections from to remove dust and debris from meter loop to motor for corrosion moving parts of the motor. (Don’t and clean if necessary. Coat the exceed 50 psi of air pressure.) wiring (especially aluminum) and Periodically: connectors with an antioxidant that Clean grass or debris from air ven- meets electrical code requirements. tilation openings on the motor and Check electrical connections from the from around the motor to allow a meter loop to the motor for tightness. full flow of cooling air. Tighten and re-tape if necessary. Check screens on motor ventilation Replace overheated connections or openings. Replace with machine wires with new material. Overheated cloth (¼-inch mesh) as necessary. connections will show heat damage such as burnt insulation on wires. At end of season shutdown: Cover the motor with a breathable Motor Bearings water-resistant tarp. Lubricate the motor according to the man- ufacturer’s instructions. Intervals between Motor Electrical System lubrication will vary with motor speed, Wide temperature fluctuations during the power draw, load, ambient temperatures, year can cause electrical connections (espe- exposure to moisture, and seasonal or con- cially in aluminum wire) to expand and tinuous operation. Electric motors should contract, loosening connectors. Loose elec- not be greased daily. Bearings can be trical connections cause heat buildup and ruined by either over- or under-greasing.Page 4 ATTRA Maintaining Irrigation Pumps, Motors, and Engines
  • 5. Fill a grease gun with electric motor bearinggrease and label it so it won’t be confusedwith other types of lubricating grease. Caution: Lubrication instructions in owner’s manuals should be followedif they differ from these. Newer motorsmay have sealed bearings that cannotbe lubricated.Recommended Re-greasing Periods for Motors Horsepower Range Type of Service 1-9 10-40 50-150 Normal Duty 8 mos. 6 mos. 4 mos. NCAT photo (8-hour day) Heavy Duty 4 mos. 3 mos. 2 mos. a small amount of grease from the (24-hour day) grease port to allow for grease expan- sion during full load operation.Maintenance Tasks Replace grease plug.Change the grease at recommended inter- Control Panel Maintenancevals to remove any accumulated moisture: Control Panel Safety Precautions Remove the bottom relief plug and clean hardened grease out of pas- Never use the main disconnect to start or sageway. stop your motor. It is not intended for this purpose. Using the main disconnect to start Using a grease gun, fi ll the hous- and stop the motor will cause excessive ing with approved high tempera- wear of the contacts and arcing can occur. ture electric motor bearing grease Use the start and stop button. (refer to the manufacturer’s manual for API number of grease) until old If the overhead lines to your control panel’s grease is expelled. service are obstructed by tree branches or other items, have the utility company clear Caution: If old grease is not expelled the lines. as the new grease is pumped in, stopadding grease and have your motor Have an electrician inspect your panel tochecked by a qualified repair person. ensure that:Adding new grease without old grease Control circuits are protected withbeing removed could blow the seals the correct size and type of fuse.and push grease into the motor wind- Lightning arresters are properlyings, causing the motor to overheat installed on the meter and motorand reducing its service life. Do not side of the buss and breaker. Theyover-grease your motor. should also be mounted in a secure Run motor until all surplus grease box to protect you if they blow up. is thrown out through the bottom The service panel is properly grease port (may require 5 to 10 grounded, independently of the minutes). pumping plant. Shut off the motor and use a screw- Service head grommets are in place driver or similar device to remove and in good ATTRA Page 5
  • 6. General Maintenance If easily accessible, check magnetic starter switch contact points. Have your electrician or pump maintenance person do a Megger check on the control Periodically clean out debris, rodent panel, motor, conduits, and other electri- droppings, and nests and insects. cal connections. The Megger device applies Make sure drain hole is open. a small amount of voltage to an electrical At end of season shutdown: component and measures the electrical resistance. A Megger test can also detect Ensure that switches are in the off potentially harmful moisture in windings. or open position. Lock the panel in the off position and remove the Any time the main disconnect switch has fuses to prevent accidental startup been left open or off, operate it several times and vandalism. Removing fuses will before leaving it closed or on. Copper oxide also prevent corrosion. can form in a few hours and result in poor contact and overheating. Any type of corro- Protect exposed control boxes sion can cause poor contact, poor ground- against moisture and dust with a ing, and direct or high-resistance shorts. waterproof tarp.E ngine power Caution: After opening the control is affected by panel but before touching the con- Engine Maintenance — Diesel, altitude and trols inside, use a voltmeter to be Gasoline, Liquid Propane Gasair temperature. sure that the incoming power is dis- (LPG), and Natural Gas connected or turned off. If neces- Make a habit of checking that the engine sary, have your utility disconnect the is securely bolted to its platform; mount- power. If you have any doubts about ing bolts can vibrate loose. Regularly check the safety of your control panel, coolant, oil levels, fuel, and fan belts. If WALK AWAY AND CALL A QUALI- coolant or oil is down, check lines for leak- FIED ELECTRICIAN. Even a current age. On diesel engines, check injectors and of 15 milliamps (one milliamp is one fuel lines for leaks. one-thousandth of an amp) can cause serious injury or death. Always play Engine power is affected by altitude and air it safe! temperature. Derate engine power output by 3.5 percent for every 1,000-foot increase Maintenance Tasks in altitude over 500 feet above sea level. At season startup: Derate output by 1 percent for each 10- degree increase in air temperature above Replace fuses after checking to see that they aren’t blown. Never use 85 degrees F. oversized fuses. Engine Startup Operate disconnect switch slowly to check for alignment of blades (Beginning of Season) and clips. Maintenance Tasks Open and close the disconnect Remove tape on all engine open- switch several times to clean oxide ings and the distributor cap, and from contact points. tighten belts. Clean contacts of all dust and dirt. Charge batteries and connect them. Clean copper contacts with very fine Open fuel tank shutoff valve. sandpaper or a fi ne fi le. Replace badly pitted or burned contacts. Before starting the engine, override Never fi le silver or silver-plated con- safety switches that protect against tacts. Leave contacts clean and dry low water pressure, loss of oil pres- so dust won’t collect. sure, and overheating. After enginePage 6 ATTRA Maintaining Irrigation Pumps, Motors, and Engines
  • 7. has reached operating speed, Inspect breaker points for wear and activate the safety switches. replace if needed. Run the engine for 10 minutes, Set the gap or dwell angle and then turn it off and check oil and lubricate the rotor. coolant levels. Check timing and adjust if necessary. Check engine and pump for any Clean all connecting terminals; leaks caused by drying gaskets. cover with protectors.Engine Air System Spray silicone on electrically oper-Always replace disposable air fi lters with ated safety switches and ignitionnew ones. Cleaning can distort the fi lter and system to prevent corrosion.allow more dirt to enter. Twice a year:Maintenance Tasks In engines that have them, clean At season startup, clean and refi ll and re-gap spark plugs or replace the fi lter bath in oil-bath air clean- with plugs in the recommended heat ers and reassemble the air cleaner. range. Periodically brush blockage off the Check all terminals and electrical screen if the air induction system is connections for tightness and corro- equipped with a pre-screener. sion, and spray with corrosion inhibi- Change the air fi lter when the ser- tor (NOT grease). vice indicator signals that it’s time Remove the distributor cap and to change it: lubricate governor weights with sili- • Turn off engine before changing cone (NOT oil). air fi lter. • Wipe the outside of the cover and Engine Oil and Lubrication housing with a damp cloth and Have a sample of engine oil analyzed for remove the cover. contaminants, which signal abnormal wear. • If cover is dented or warped, Intervals between analyses will depend on replace it. the engine, and analysis may be cost-effec- tive only for larger engines. Equipment deal- • Use extreme care when remov- ers should know where the oil can be ana- ing the fi lter to prevent dirt from lyzed and how often this should be done. falling into the intake duct. Use a clean damp cloth to wipe inside of fi lter housing. • Install new air fi lter.Engine Electrical SystemIf you have a natural gas engine, be awarethat natural gas has a higher octane valuethan automotive gasoline. You can increaseengine efficiency and reduce fuel consump-tion by setting the ignition timing to takeadvantage of the higher octane. Consult theengine manufacturer for recommendationson how to do this.Maintenance TasksAt season startup: NCAT ATTRA Page 7
  • 8. Use only the oil recommended by the manufac- Remove spark plugs. Pour a table- turer. Tag each engine with a label identifying spoon of clean motor oil into each the proper oil. spark plug hole. Position spark plug wire away from cylinder opening Maintenance Tasks and rotate crankshaft by hand to Twice a year: lubricate piston and rings. Replace spark plug. If the engine was not protected during shutdown, or if the oil has Seal the distributor cap with duct not been changed within the last tape where the cap joins the dis- year, change the crankcase oil and tributor housing. oil fi lter. Seal all the openings in the engine Lubricate all engine accessories with duct tape, including air cleaner such as the driveshaft and U-joints. inlet, exhaust outlet, and crankcase breather tube. Engine Fuel and Coolant If the engine coolant is water, drain and refi ll the cooling systemD Maintenance Tasks o not store with water, a rust inhibitor, and Twice a year remove and clean or antifreeze. batteries replace the fuel fi lter. directly Remove tension from belts. Periodically check that fuel tank capon concrete. and oil fi lter cap are on tight and Remove and store batteries in a cool that gaskets aren’t cracked. but not freezing location. Do not store batteries directly on concrete. Periodically check that the fluid level and degree of coolant protec- If engine is outside, cover with a tion are adequate. Check that the water-resistant tarp. radiator cap is on tight and that gas- kets aren’t cracked. Centrifugal Pump Maintenance Centrifugal Pump Startup Engine Shutdown (End of Season) (Beginning of Season) Maintenance Tasks Maintenance Tasks Drain all fuel from the tank and lines and shut off the fuel valve. If Using new gaskets and pipe-dope, LP gas is used, drain vaporizer- reconnect to the pump any piping regulator. (Drain both fuel and removed during shutdown. water lines.) Re-install the primer and priming valve if they were removed during shutdown.Figure 4. Centrifugal Pump and Motor Check that the pump shaft turns freely and is free of foreign objects. Applying power could break the impeller if it’s rusted to the case. Check the pump for leaks caused by drying gaskets. Check intake and discharge pip- ing for proper support and make sure the pump is securely bolted to the platform. Clean the drain hole on the under- side of the pump.Page 8 ATTRA Maintaining Irrigation Pumps, Motors, and Engines
  • 9. GeneralTo avoid water leaks, make sure that all gas-kets are the correct ones for the coupling orflange. Eliminate air leaks in your pump’ssuction line by coating threaded connectionswith pipe cement or white lead and drawingthem tight. Also examine suction line weldsfor cracks, which will allow air leaks. Choosing Gaskets Using a gasket in a coupling that it was not made for is a common cause of leaky gaskets. Get the right gasket and the right kind of gas- ket for the fitting. Flat gaskets: Most are made of neoprene and are used on flanged, bolt-together fittings. They are usually not expensive. They normally NCAT photo fail by “creeping” out of their fitting. Look for connections between pump and primer. On new neoprene gaskets that contain a cotton backing sandwiched in the gasket to reduce a hand primer, if grass or other debris is the creeping action. lodged in the check valve, air is pulled back into the pump at every stroke and the pump Shaped gaskets: The three most common won’t prime. After proper priming, fi ll the materials are styrene-butadiene (SBR), eth- system slowly. ylene-propylene (EPDM), and polyethylene (poly). SBR and EPDM have much better resis- Maintenance Tasks tance to cracking, abrasion, ozone, and weath- Twice a year: ering resistance than poly gaskets. They are more expensive than poly but will last longer. Thoroughly clean suction and dis- When buying shaped gaskets, look for gaskets charge piping and connections, that are dull; this indicates that little or no plas- removing moss and debris. ticizer has been added to the gasket. Plasticiz- ers significantly reduce gasket life. Tighten all drain and fi ll plugs in the pump volute case to avoid air and water leaks. Use a pipe threadIf your pump isn’t delivering water, verify compound on all pipe threads. Figure 5. Impeller Eyethat the pump shaft is turning in the direction Check for cracks or holes in the and Wear Ringof the arrow on the pump casing. As viewed pump case.from the motor end, the rotation is usuallyclockwise, but check the startup instructions Clean trash screening device andthat came with the pump. On three-phase screens on the suction pipe.motors, swap any two power leads to change Impellerrotation. It is recommended that a qualified Servicing Impeller and Wear Ringselectrician perform this task. If you suspect that your pump impeller is clogged or damaged, or that the wear ringsIf the pump doesn’t prime, check for air are worn, you can dismantle the pump. This 1/32” clearanceleaks on discharge valves. Many all-metal will take some work and is best done in thegate-type valves won’t seal properly to cre- shop. Or have a qualified pump repair shopate a vacuum. Sand or other debris lodged undertake this procedure. Always followbetween the rubber flap and the valve seat the directions in the manufacturer’s man-will prevent check valves from sealing andforming a tight joint. See if the rubber face ual, if available, instead of the followingis cracked or chipped and not seating. simplified directions.Replace the gate valve or check valve. Check Remove suction cover or volute ATTRA Page 9
  • 10. dirt, silt, or sand in the water can also score Net Positive Suction Head (NPSH) and Cavitation the sleeve. Many people are surprised to learn that centrifugal pumps don’t pull Check for an improperly greased or worn water through a suction pipe; they can only pump water that is delivered rotary shaft seal by running the pump and to them. When air is removed from the suction pipe by a primer pump, the weight of the earth’s atmosphere forces water to rise into the pipe, squirting oil on the shaft just outside the seal. delivering water to the pump. Oil drawn into the seal indicates a leak. Even in the best of circumstances (including a near-perfect vacuum), If the pump has been out of service, the the maximum water column that can be forced by atmospheric pressure packing may be dried and hardened. Air never exceeds about 33 feet in height. As elevation, water temperature, can leak into the pump through the packing and pipe friction increase, the height of the water column that can be box and the pump can lose prime. forced drops. The maximum column of water that can be created in a pipe under a given set of conditions is known as Net Positive Suction Head or NPSH. Maintenance Tasks Insufficient NPSH often occurs at startup. Since the pump is working Grease the packing box annually with a against low pressure, it pumps a larger volume than in normal opera- proper pump packing grease. Less frequent tion. This larger volume creates friction losses in the suction line, reduc- maintenance causes grease to harden, mak- ing NPSH. Too little available NPSH can result in vaporization of water ing this task very difficult. in the eye of the impeller, causing cavitation, a noisy condition where vapor bubbles collapse violently in the pump. If the packing box is equipped with a grease cup or a grease zerk, To stop cavitation, close the discharge valve. If cavitation is allowed to continue, the impeller and pump casing can become pitted and apply a couple pumps of pack- damaged, reducing pump capacity. To eliminate cavitation as well ing grease to the packing box to as water hammer, and to prevent high amperage draw on demand force out the remaining water and meters, open the discharge valve slowly to fill the mainline whenever protect the packing. you start up the pump. For a packing box without a grease Caution: Don’t let the pump run more than two minutes with the discharge cup or zerk, remove the last two valve closed. packing rings (see below for replac- ing packing) and discard. Pack Remove debris from impeller and packing grease into the packing box volute. Remove pebbles lodged until full. Add two new rings and between vanes. gently tighten the packing gland slightly to force the grease into the Check wear at the impeller eye and subsequent packing rings. Then vanes. If worn, repair or replace the loosen the gland. impeller. Re-machine or replace wear ring if clearance is greater Figure 6. Pump Packing than 1/32 inch per side. Replace suction cover or volute. Use a new gasket. Servicing the Pump Packing A pump with shaft sleeve and pack- ing in good condition and properly adjusted shouldn’t require con- stant re-adjustment, but should be checked daily. Unless proper leak- age (about 8 to 10 drops per minute) is running through the packing box, the packing will become overheated and dry out, eventually burning and scoring the shaft sleeve. ExcessivePage 10 ATTRA Maintaining Irrigation Pumps, Motors, and Engines
  • 11. Replacing the Packing Successive rings of packing should be installed so the joints are 120Old packing should be replaced completely degrees apart.if leakage cannot be reduced by addinga new packing ring to the old packing, or Install lantern ring (if required) inif the packing is burned (dried up and proper position to the packing rings asscorched) or has leaked excessively during shown on your manual’s parts page.the season. Install packing gland so that it just Caution: This task is difficult. Have begins to enter the stuffing box a qualified pump repair shop do it if straight, making sure that the full you are in doubt. If you are attempt- packing is under uniform pressure. ing the procedure yourself, do it in Seal the gland with clip, stud, the shop rather than in the field. and nut. Remove packing box gland nut If the packing is equipped with a with a wrench. Remove the gland grease fitting, add a shot of grease. and packing. Before inserting the last two packing O To remove packing, twist two pack- rings on boxes without a grease cup nce the ing pullers 180 degrees apart into or zerk, pack grease into the pack- packing is the exposed packing ring. Pull each ing box until full. Add the last two ring out of the packing box cav- burned and rings and tighten the packing gland ity until all are removed. The lan- slightly to force the grease into the the shaft sleeve is tern ring has two holes 180 degrees subsequent rings of packing. Then scored, no amount apart and can be removed with the loosen the gland. of adjustment will packing pullers. Start the pump with the packing maintain proper Replace the shaft sleeve if it is worn gland loose so there will be initial leakage for any or grooved. This usually requires leakage. Tighten the packing gland length of time. pump disassembly. Once the pack- only enough to draw the necessary ing is burned and the shaft sleeve vacuum for priming. is scored, no amount of adjustment Tighten the gland nuts slightly and will maintain proper leakage for any evenly every 15 to 20 minutes, until length of time. leakage is reduced to about 8 to Before replacing new packing, 10 drops per minute and the water insert the packing gland to make leaking from the box is cool. sure it enters freely to the gland’s Caution: Don’t stop leakage entirely. full depth. If it doesn’t, clean out the fragments of old packing and other debris that may be obstructing it. Centrifugal Pump Shutdown Install new packing rings as far for- (End of Season) ward as can be reached. Install only In cold climates, it is critical that all the type and size of packing recom- water be drained from pumps prior to mended by the manufacturer. freezing weather. Insert each ring separately. Push Maintenance Tasks it securely into the box and seat it fi rmly. A small amount of packing Remove suction and discharge piping grease applied to the packing will in areas where ice is a problem. Make make this job a little easier. Don’t sure drain valves are not plugged, use sharp points to push the pack- and drain water from the pump. ing into the box. (Use the packing Cover any exposed metal, such as gland, a wooden dowel, pliers han- the shaft, with protective lubricant dle, fi ngers, or other blunt object.) to prevent ATTRA Page 11
  • 12. Cover all oil- or grease- Maintenance Tasks lubricated bearings At season startup: with lubricant so mois- ture won’t rust and Change the oil in the oil bath or pit them. reservoir for the pump upper bear- ings. Fill with approved turbine oil Remove tension from almost to the top of the sight glass any belts. so bearings are covered, taking Open petcock and care that excess oil doesn’t get on drain diaphragm-type or in the motor.NCAT photo hand primer. Periodically: If the discharge primer valve is equipped with a rubber seat, coat it Grease lower bearings. Refer to with rubber preservative. electric motor bearing greasing Any rubber parts in a flexible cou- instructions above, on page 5. pling connecting the pump to the Maintain the pump packing on water- driver should also receive a coating lubricated turbine pumps as directed of preservative. above on pages 10 to 11 for centrifu- Make sure the ball valve on the gal pump packing. pressure gauge riser is closed. Annually: Remove the pressure gauge and store inside. Change the bearing oil in vertical hollow shaft motors. When replacing Seal all openings, including suc- tion, discharge, and primer, with the oil, follow motor manufacturer’s duct tape, to keep out rodents and recommendations or use ISO-VG32 foreign material. turbine oil, such as: Cover the pump with a water- Mobil DTE 797 proof tarp. Lubriplate HO-0 Turbine Pump Maintenance Chevron Turbine Oil GST32 Shell Turbo T Oil 32 GeneralFigure 7. Oil-Lubricated Turbine Pump Some of the instructions Maintain bearing oil at the proper level. below also apply to sub- Overfi lling the oil reservoir can cause oil mersible pumps. to overflow when the motor heats up during operation. The excess oil will adhere to the Make a habit of periodi- motor and to ventilation screens, collecting cally checking that dis- dirt and debris and reducing the motor’s charge piping is firmly ability to dispel heat. supported in the area near the pump. Make sure the pump is securely Short-Coupled Turbine Pump bolted to the platform. Maintenance Tasks If your turbine pump At season startup for oil-lubricated pumps: is installed over a well and you’ve experienced Fill the oil reservoir and start the oil water supply problems, flowing to the pump one hour before check the static level and starting the pump. Check to see that drawdown in the well. the oil tube is fi lled before running A deeper pump setting the pump. The pump needs about might be required. 10 drops per minute.Page 12 ATTRA Maintaining Irrigation Pumps, Motors, and Engines
  • 13. At season startup for water-lubricated Maintenance Tasksturbine pumps: At season startup for oil-lubricated pumps: Pre-lubricate line shaft bearings Start lubricating the shaft up to a with light oil. week before starting the pump,Periodically: or until the line shaft and column are full of oil and the oil begins to Adjust and maintain the pack- run out at the top near the stretch ing on water-lubricated, short-cou- assembly. During this fi rst week, pled turbines as directed for the allow four to five drops of oil per packing on a centrifugal pump. minute. After starting, increase to (See pages 10 to 11 above.) 10 to 15 drops of oil per minute.Annually (or according to manufacturer’s Check the manufacturer’s instruc-recommended interval) adjust the head tions to be sure of the requirement.shaft nut on short-coupled turbine pumps: (Oil will drip slower at night when it Remove the top motor cover and cools down.) The viscosity rating of take out the set screw. the oil should be 9 or 10. Remove, clean, oil, and replace the Periodically: key stock. adjust and maintain the packing on water-lubricated deep well turbines, Loosen the head shaft adjusting nut following the same procedures as for (it has a left-hand thread) so the shaft the packing on a centrifugal pump. and bowls are resting on the bottom. (See pages 10 to 11 above.) Tighten the head shaft adjusting nut two turns, which will raise the shaft and bowl assembly enough to allow Submersible Pumps A submersible pump is a turbine pump that is close-coupled to a submers- for proper clearance. ible electric motor. Since both pump and motor are suspended in the water, You should be able to turn the shaft the drive shaft and bearings required for a deep well turbine pump are elimi- by hand once it’s raised. If you nated. The pump is located above the motor and water enters the pump through a screen located between the pump and motor. can’t, tighten the head shaft adjust- Submersible pumps use enclosed impellers. The motors are smaller in diam- ing nut one-half turn and try to turn eter and longer than turbine pump motors. Inadequate circulation of water it by hand again. past the motor may cause it to overheat and burn out. The riser pipe must Replace t he set screw a nd be of sufficient length to keep the bowl assembly and motor completely submerged at all times and the well casing must be large for water to easily motor cover. flow past the motor. Electrical wiring from the pump to the surface must be watertight with sealed connections. Caution: If you are unable to turn the shaft by hand, and you haveraised the shaft by five or more turns Troubleshootingof the nut, remove the pump, disas- This section identifies symptoms and pos-semble, and inspect for damage or sible causes under Suction, System, anddebris. If you have any questions Pump. (See Troubleshooting Tables on theabout this procedure, consult your following page.) Find the Symptoms andpump dealer. then look across to the left to see possible causes. Most often, suction problems areDeep Well Turbine Pump the cause. Contact your pump repair shop for additional help.Shaft adjustment needs to be more precisefor deep well turbines. Shaft stretch needs Caution: This troubleshooting guideto be considered. Refer to the manufac- is general and does not cover allturer’s instructions or consult a qualified the possible system configurations orpump dealer. problems that might be ATTRA Page 13
  • 14. Troubleshooting Tables Symptoms Symptoms Pump has insufficient capacity (gpm) Pump has insufficient capacity (gpm) Packing box leaks water excessively Packing box leaks water excessively Pump loses prime after starting Pump loses prime after starting Pump requires excessive power Pump requires excessive power Pump has insufficient pressure Pump has insufficient pressure Pump does not deliver water Pump does not deliver water Pump overheats and seizes Pump overheats and seizes Packing box has short life Packing box has short life Pump vibrates or is noisy Pump vibrates or is noisy Bearings have short life Bearings have short lifeCauses of Causes ofSuction Problems Pump Problems Rotary shaft seals (packing) leak air Pump not primed Foreign matter in impeller Insufficiently submerged Wear rings worn suction pipe inlet Impeller damaged Pump or suction pipe not Defective pump casing gasket completely filled with water permitting internal leakage Insufficient Net Positive Suction Misalignment of pump and Head (NPSH – See pg. 20) driving unitSuction line, strainer, or centrifugal Bent shaft between pump and pump balance line plugged motor or engine Air leaks into suction line Rotating part rubbing on stationary part of motor Air leaks into pump through Packing gland too tight resulting in packing box no water flow to lubricate Excessive amount of air or packing and shaft gas in the water Packing worn, improperly installed, Foot valve too small, insufficiently or incorrect for operating conditions submerged, or partially clogged Cooling water not getting to water- cooled packing boxes Packing forced into pump interior Shaft or shaft sleeves worn or scored at the packing Shaft running off center Symptoms Impeller or rotor (electric motors) out of balance Pump has insufficient capacity (gpm) Packing box leaks water excessively Bearings worn Pump loses prime after starting Pump requires excessive power Pump has insufficient pressure Foundation or platform not rigid or Pump does not deliver water Pump overheats and seizes mounting is loose Packing box has short life Pump vibrates or is noisy Bearings have short life Pipe not supported Under- or over-greasing of bearings or greasing sealed motor bearingsCauses of Condensation of atmospheric moisture in the bearing housingSystem Problems Lack of lubrication or improper lubrication Speed (rpm) too low Scoring or rusting of bearings in Parallel operation of pumps turbine pump unsuitable Improper installation of bearing, Total system head higher than incorrect assembly of stacked pump design head bearings, and use of unmatched bearings as a pair (turbine pump) Wrong direction of pump rotation Excessive thrust (seen as shaft Speed (rpm) too high movement from mechanical Total system head lower than failure or failure of hydraulic pump design head balancing device)Page 14 ATTRA Maintaining Irrigation Pumps, Motors, and Engines
  • 15. References Maintaining Electric Motors Used for Irrigation. 2000. By Richard F. Beard and Robert W. Hill. Utah StateBlack, Richard D., and Danny H. Rogers. 1993. Eval- University Extension Service, Logan, UT. 5 p.uating Pumping Plant Efficiency Using On-Farm Fuel Describes factors that affect electric motor performanceBills. Kansas State University Cooperative Extension and service life and describes procedures for controllingService, Manhattan, Kansas. 4 p. internal motor heat. Can be downloaded from, J.C., and D.L. Miles. 2004. Irrigation Pumping fi les/engrpubs/biewm06.pdf.Plant Efficiency. Colorado State University CooperativeExtension Service, Fort Collins, CO. 4 p. Irrigation Engineering University of Nebraska Institute of Agriculture and Natural Resources. Resources Dozens of publications on irrigation management andNCAT Publications hardware.The Montana Irrigator’s Pocket Guide. 2003. By MikeMorris, Vicki Lynne, Nancy Matheson, and Al Kurki. WaterightNational Center for Appropriate Technology, Butte, Center for Irrigation Technology at California StateMT. 161 p. University, Fresno. A take-to-the-field reference to help irrigators save A “multi-function, educational resource for irrigation energy, water, and money; includes guidelines for water management.” Includes an energy use/cost cal- water management, equipment maintenance, and culator, guidelines for estimating fuel requirements, handy conversions and formulas. Get a free printed options for reducing energy use and costs, and discus- copy by calling 800-346-9140 (toll-free). sions of various other energy-related topics.Other Publications and Web sitesExtending Electric Motor Life. Hansen, Hugh J. andWalt L. Trimmer. PNW 292. Oregon State University,Corvallis, OR. 4 p. Available from Oregon State University Extension Service. Cost $0.25. Order from 541-737-2513, 800-561-6719, or puborders@oregonstate.eduIrrigation Energy Saving Ideas. 2000. By RichardF. Beard and Robert W. Hill. Utah State UniversityExtension Service, Logan, UT. 5 p. Describes factors that affect electric motor performance and service life and describes procedures for controlling internal motor heat. Can be downloaded from http:// les/engrpubs/biewm06.pdf.Irrigation Water Pumps. 1993. By Thomas F. Scherer.Publication AE1057. North Dakota State UniversityExtension Service, Fargo, ND. 12 p. Covers basic operating characteristics of centrifugal, deep well turbine, submersible, and propeller pumps, as well as pump power requirements and selection criteria. Can be downloaded from www.ext.nodak. edu/ ATTRA Page 15
  • 16. Maintaining Irrigation Pumps, Motors, and Engines By Mike Morris and Vicki Lynne NCAT Energy Specialists © 2006 NCAT Paul Driscoll, Editor Amy Smith, Production This publication is available on the Web at: or IP299 Slot 294 Version 091306Page 16 ATTRA