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A Pacific Northwest Extension Publication Oregon State University, Washington State University, University of Idaho Irrigation System Walk-through Inspection Analysis PNW 293 Reprinted October 1997 H. Hansen and W. Trimmer Do you want to print a copy? We recommend downloading the print version (31 K). First download the free Adobe Reader, if you don't already have it. Suction system Pump and fittings Electric motor Electric service Mainline system Stationary and moving laterals Risers and sprinklers This "walk-through" worksheet provides a method for making an organized inspection of an entire irrigation system, both hydraulics and hardware. This inspection will help identify components that need maintenance, repair, replacement, or other attention-so that the system will provide the most satisfactory, safe, and efficient performance. OK  Needs attention Suction system Inspect system from water supply to pump intake. Generally, suction line should provide smooth water flow with a minimum of fittings that cause obstructions, water turbulence, or head losses. From surface supplies and shallow wells Note: On shallow wells with aboveground pump mounting, consider pulling suction line to make starred (*) checks.      1. Trash screening device (if used) clean and properly placed.  _____  _____   *2. Intake screen clean, good condition, properly placed.  _____ _____   *3. Foot or check valve operating smoothly.  _____ _____   *4. Suction line does not collapse when pumping.  _____ _____   *5. Suction pipe size/pump capacity properly matched to maintain flow velocity at 5 feet per second (fps) or less (preferably 2-3 fps).  _____ _____ *6. Maximum elevation rise from water surface to pump impeller eye does not exceed 10 feet. Required net positive suction head (NPSH) must not exceed NPSH available; see pump performance curve.   _____ _____   *7. Suction pipe inlet submerged adequately to prevent entrance of air and eddying of water. _____ _____   *8. Suction line free of air leaks. _____ _____   9. No unnecessary or undersized plumbing fittings in suction line to increase friction losses. _____ _____   10. Elbows, bends of flanged type. _____  _____  11. Couplings flanged or smooth interior bore. _____   _____   12. Eccentric adapter to pump with 12o taper (not over 28o). _____   _____   13. Eccentric adapter installed with slope on bottom side. _____   _____   14. Straight pipe at least 4 diameters in length before pump inlet to reduce water turbulence, cavitation.  _____   _____   15. Horizontal suction line to pump sloped upward at least 1/4 inch per foot. _____   _____   16. High point of suction line at pump entrance to eliminate air entrapment. _____   _____   17. Vacuum gauge or port installed on suction line. _____   _____   18. No part of suction piping smaller in diameter than pump suction inlet.           _____   _____ From deep wells      1. Well casings properly located and perforated to allow water intake without cascading or introducing air into impellers.  _____  _____  2. Bowls set below water drawdown level.  _____  _____  3. Bowl settings properly adjusted.  _____  _____  Pump and fittings Inspect pump assembly with its associated inlet and discharge fittings. Consider motor separately.      Above-ground centrifugal pumps      1. Sturdy pump base with pump firmly attached.  _____  _____  2. Intake pipe firmly supported within 3 feet of pump. _____ _____ 3. Discharge pipe firmly supported within 3 feet of pump.  _____ _____ 4. Impeller rotates freely in casing.   _____ _____ 5. Pump operates with no excess vibration.  _____ _____ 6. Bearings in good condition.  _____ _____ 7. Shaft properly aligned with motor.  _____ _____ 8. Impeller firmly attached to shaft.   _____ _____ 9. Stuffing, seals, shaft packing adjusted for proper water drip lubrication. _____ _____ 10. Wear ring in good condition with no deposition, cavitation, or abnormal configuration.  _____ _____ 11. Water velocity in pipeline at 5 fps or less.  _____ _____ 12. Pressure gauge or port at pump discharge.  _____ _____ 13. Discharge increaser has 12o taper (maximum 28o).  _____ _____ 14. Increaser near as possible to pump.  _____ _____ 15. Straight pipe run out of pump discharge to minimize turbulence (for flow measurement).  _____ _____ 16. No unnecessary or undersized fittings in discharge line that increase friction losses: _____ _____ Size, location of trees _____ _____ Size, location of elbows, bends _____ _____ Size, location of valves _____ _____ Size, location of couplings, unions _____ _____ Size, location, taper of enlargers _____ _____ 17. Flow meter with low flow restriction.  _____ _____ 18. Air relief valve at high point in system to release trapped air.   _____ _____ 19. Isolation valve on primer pump.  _____ _____ Deep well turbines      1. Sturdy motor base; motor firmly supported.  _____  _____ 2. Discharge pipe firmly supported.   _____ _____ 3. Pump operates with no excess vibration.  _____ _____ 4. Pump lubricated with turbine-type oil.  _____ _____ 5. Oilers working properly.   _____ _____ 6. Working airline in well to measure drawdown.  _____ _____ 7. Water velocity in pipeline at 5 fps or less.  _____ _____ 8. Pressure gauge or port in discharge line.  _____ _____ 9. Concentric discharge fitting, if appropriate.  _____ _____ 10. Straight pipe run out of pump discharge to minimize turbulence (for flow measurement).  _____ _____ 11. No unnecessary or undersized plumbing fittings in discharge line that increase friction losses: Size, location of tees Size, location of elbows, bends _____  _____ Size, location of valves  _____ _____ Size, location of couplings, unions  _____ _____ Size, location, taper of enlargers   _____ _____ 12. Flow meter with low-flow restriction.  _____ _____ 13. Air relief valve at high point in system to release trapped air.  _____ _____ Electric motor Inspect motor for mechanical and electrical soundness.     1. Sturdy base mounting.   _____ _____ 2. Proper shaft alignment with pump.  _____ _____ 3. Proper belt alignment and tension between motor and pump.  _____ _____ 4. Motor bearings in good condition, properly lubricated.  _____ _____ 5. Motor frame free of debris, vegetation, straw, caked-on dirt and oil, rodent or insect nests.  _____ _____ 6. Motor ventilation vents open, unobstructed, and protected with 1/4- to l/2-inch mesh screen. _____ _____ 7. Cover over motor for shade and rain protection.  _____ _____ 8. Unobstructed ventilation around motor-if in motor house, ample-sized openings on opposite walls for ventilation.  _____ _____ 9. Good drainage away from motor base.  _____ _____ 10. Wiring to motor in good, safe condition.  _____ _____ 11. Safety shields attached and functioning.  _____ _____ 12. Access plates and cover dome in place and secure.  _____ _____  13. Motor free of evidence of excess heat due to electrical overloading.   _____ _____ 14. Motor runs quietly, free of excess vibration or noise.  _____ _____ Electric service Inspect electric service for safety and serviceability.      1. Overhead lines free of tree branches, other physical obstructions.  _____ _____ 2. Conductors properly secured to prevent flexing, shorting hazards.   _____ _____ 3. Conductors free of frayed, cracked, or worn insulation.  _____ _____ 4. Service panel properly grounded independently of pumping plant.   _____ _____ 5. Service head grommets in place, in good condition.  _____ _____ 6. All conduit or shielded cable in good condition.  _____ _____ 7. Service panel properly, securely installed.  _____ _____ 8. Service panel has functioning interlocking door latches, padlock.   _____ _____ 9. Service panel door has adequate seals and/or drip traps.  _____ _____ 10. Service panel free of open holes, missing knockout plugs.  _____ _____ 11. Electrical connections within service panel secure, free of signs of arcing.   _____ _____ 12. Service panel interior free of moisture, corrosion, insects, rodents, snakes.  _____ _____ 13. Lightning arrestors properly installed on meter and motor side of buss and breaker.  _____ _____ 14. Overload protection properly sized.   _____ _____ 15. Circuit breakers operable; no slugs or copper bars used in place of fuses.   _____ _____ 16. Shade over service panel to cool thermal breakers.  _____ _____ Mainline system Inspect entire mainline from pump to terminal end.      1. Pipe condition:      Bent or flattened piping  _____ _____ Split seams  _____ _____ Bullet holes or other punctures  _____ _____ Leaky joints, connections, valves  _____ _____ Gaskets worn, sand or dirt behind  _____ _____ Leaky end plugs  _____ _____ 2. If buried, mainline protected and covered.  _____ _____ 3. Evidence of sink holes indicating unsupported piping.  _____ _____ 4. Line designed and sized for minimum hydraulic turbulence or friction.  _____ _____ 5. Pipe size adequate to handle water discharge at flow rate of 5 fps or less.  _____ _____ 6. No unnecessary or undersized plumbing fittings in line to increase friction losses:     Elbows, bends  _____ _____ Tees  _____ _____ Valves  _____ _____ Reducers, enlargers  _____ _____ Couplings, unions  _____ _____ 7. Flow meter with low flow restriction.   _____ _____ 8. Air release valves and vacuum relief installed as needed on high points of line.  _____ _____ 9. Provision made to drain and flush line if subject to freezing.  _____ _____ 10. Line equipped with check valve, if needed.  _____ _____ 11. Pressure relief valve set at 10 psi above normal operating pressure.  _____ _____ Stationary and moving laterals     1. System layout compatible with topography; if not, appropriate pressure control devices used.   _____ _____ 2. Lateral spacing on mainline satisfactory.  _____ _____ 3. Adequate water flow rate and pressure.  _____ _____ 4. System free of leaks from breaks, couplers, drain valves, risers, end plugs.  _____ _____ 5. System free of excessive corrosion or wear.  _____ _____ 6. Chains, bearings, drive gears of all wheelmove systems in good operating condition.  _____ _____ 7. Electric motors covered and protected.  _____ _____ 8. Pipe condition:  Bent or flattened piping  _____  _____ Split seams  _____ _____ Bullet holes or other punctures  _____ _____ Leaky joints, connections, valves   _____ _____ Gaskets worn, sand or dirt behind  _____ _____ Risers and sprinklers  Walk the entire sprinkler line to inspect the following:     1. Mainline valves and gaskets in good condition.  _____ _____ 2. Risers all in place, no broken units.   _____ _____ 3. Self-leveler risers operating freely, properly aligned.  _____ _____ 4. Sprinkler heads operating properly, no plugged nozzles.  _____ _____ 5. Sprinkler nozzles properly sized, not worn (check orifice by using shank of high-speed drill bit as a gauge).  _____ _____ 6. Sprinkler heads rotate smoothly and freely at 1 to 2 revolutions per minute.  _____ _____ 7. Sprinkler head base gaskets in good condition.  _____ _____ 8. Visual inspection of each sprinkler indicates uniform application pattern.   _____ _____ 9. Pressure at sprinkler appropriate.   _____ _____ 10. Sprinklers match operating pressure.  _____ _____ top Prepared by Hugh J. Hansen, Extension agricultural engineer emeritus; and Walter L. Trimmer, former Extension irrigation specialist; Oregon State University. Reprinted October 1997.

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