Troubleshooting vertical turbine pumps in agriculture

Troubleshooting Vertical Turbine Pumps

Marketing Pumps

As a part of our ongoing commitment to providing informative irrigation related resources for growers, ranchers, and ranch/farm managers, we have compiled a summary of vertical turbine pump troubleshooting instructions for pumps commonly used in ag irrigation systems across California. 

This article is based on material published by Peerless Pump, a leading supplier of vertical turbine pumps. Although this is a practical guide for most vertical turbine pumps, it’s strongly recommended that you follow the manufacturer’s recommendations for your specific pump make/model.

It is also recommended that you carefully read and follow the Important Safety Precautions found at the end of this article before attempting to service or repair any pump related equipment.

Troubleshooting vertical turbine pumps in agriculture

TROUBLE SOURCE: Insufficient Pressure

Probable causes >> Remedy

  1. Speed too slow >> Check motor for correct voltage, speed, hp. Replace motor if necessary.
  2. Improper impeller trim >> Remove pump and replace Impeller.
  3. Impeller loose >> Pull pump and tighten Impeller.
  4. Cavitation >> Increase pump submergence, lower pumped liquid temperature, check sump for compliance with HI recommendations, redesign sump if necessary.
  5. Wear rings worn >> Pull pump and inspect for bent shaft, straighten bent shaft, replace wear ring, remove any abrasive material, adjust Impeller setting per Peerless recommendations.
  6. Leak in the discharge piping system >> Plug leaks or change pipe section.
  7. Leaking column joints or bowl castings >> Change column gasket or “O” ring, tighten all boltings and nuts to recommended torque ratings, replace or repaire leaky castings.
  8. Wrong rotation >> Check pump for CCW rotation when viewed from top of motor. If necessary reverse motor rotation by swapping two leads in the motor terminal box.

TROUBLE SOURCE: Insufficient Capacity

Probable causes >> Remedy

  1. Speed too slow >> Check motor for correct voltage, speed, hp. Replace motor if necessary.
  2. Improper impeller trim >> Remove pump and replace Impeller.
  3. Impeller loose >> Pull pump and tighten impeller.
  4. Impeller or bowl partially plugged >> Disassemble pump, inspect and remove foreign material, reassemble and set impeller with correct lateral settings.
  5. Leaking joints >> Change column gasket or “O” ring, tighten all boltings and nuts to recommended torque ratings, replace or repair leaky castings.
  6. Strainer partially clogged >> Remove strainer from pump, inspect and clean.
  7. Suction valve throttled >> Check for fully open position or partially closed position.
  8. Low water level in sump >> Increase min water level in sump.
  9. Wrong rotation >> Check pump for CCW rotation when viewed from top of motor. If necessary reverse motor rotation by swapping two leads in the motor terminal box.
  10. Total pump head is too high >> Check Discharge piping for friction losses. Larger piping may correct problem.

TROUBLE SOURCE: No Liquid Delivered

Probable causes >> Remedy

  1. Pump suction broken (water level below bell inlet) >> Increase min water level in sump, refer to min water level requirements of individual pump.
  2. Suction valve closed >> Open suction valve.
  3. Impeller plugged >> Disassemble pump, inspect and remove foreign material, reassemble and set impeller with correct lateral settings.
  4. Strainer clogged >> Remove strainer from pump, inspect and clean.
  5. Wrong rotation >> Check pump for CCW rotation when viewed from top of motor. If necessary reverse motor rotation by swapping two leads in the motor terminal box.
  6. Shaft broken or unscrewed >> Replace broken shaft, retighten couplings.
  7. Impeller loose >> Pull pump and tighten impeller.

TROUBLE SOURCE: Using Too Much Power

Probable causes >> Remedy

  1. Speed too high >> Check motor for correct speed, Replace motor if necessary.
  2. Improper impeller adjustment >> Adjust Impeller lateral setting per Peerless recommendations.
  3. Improper impeller trim >> Change Impeller or reduce Impeller diameter.
  4. Pump out of alignment or shaft bent >> Check for overall pump concentricity, remove and straighten the bent shaft, consider replacing the bent shaft.
  5. Mechanical binding >> Packing rings adjusted too tight Loosen packing rings to release gland pressure. Ensure adequate lubrication flow per Peerless Pump recommendations.
  6. Damaged impeller >> Pull pump, inspect and replace impeller if damaged.

TROUBLE SOURCE: Vibration

Probable causes >> Remedy

  1. Motor imbalance >> Field balance motor.
  2. Motor bearings not properly seated >> Inspect and replace as required.
  3. Motor drive coupling out of balance >> Field balance coupling.
  4. Misalignment of pump, casting, discharge head, column, or bowls >> Check for overall pump concentricity, remove and straighten the bent shaft, consider replacing the bent shaft.
  5. Discharge head misaligned by improper mounting or pipe strain >> Reduce pipe strain, ensure pipe strain does not exceed limits recommended by Peerless Pump.
  6. Bent shafting >> Remove and straighten the bent shaft, consider replacing the bent shaft.
  7. Worn pump bearings >> Pull pump and inspect for bent shaft, straighten bent shaft, replace wear ring, remove any abrasive material, adjust Impeller setting per Peerless recommendations.
  8. Clogged impeller or foreign material in pump >> Disassemble pump, inspect and remove foreign material, reassemble and set impeller with correct lateral settings.
  9. Improper impeller balance >> Remove Impellers and balance per Peerless Pump recommendations.
  10. Vortex problems in sump >> Adding of baffels or flow direction devices can reduce this.
  11. Resonance – system frequency at or near pump speed >> Stiffening or softening the system can be accomplished by many different methods.

TROUBLE SOURCE: Abnormal Noise

Probable causes >> Remedy

  1. Motor noise >> Pump bearings running dry. Check for minimum submergence, ensure min water level is above the centerline of first stage impeller.
  2. Broken column bearing retainers >> Remove and replace bearing retainers, consider replacing bearings.
  3. Broken shaft or shaft enclosing tube >> Disassemble pump and replace.
  4. Impeller dragging on bowl case >> Adjust Impeller setting per Peerless recommendations.
  5. Cavitation due to low submergence or operation beyond maximum capacity rating >> Increase submergence.
  6. Foreign material in pump >> Disassemble pump, inspect and remove foreign material, reassemble and set impeller with correct lateral settings.

Suggested Maintenance Schudules

Pumps

  • Check pump packing for adequate leakage – Daily
  • Check and lubricate pump packing as needed – Monthly
  • Check pump discharge flow and head to ensure operation within acceptable range – Annually
  • Replace packing when leakage cannot be controlled by tightening the packing gland – As Needed

Motors (see specific manufacturer instructions)

  • Check oil level and refill as needed – Weekly
  • Inspect oil in reservoirs for condensation; flush and refill if condensation is present – Monthly
  • Check vibration monitors to ensure operation within acceptable limits – Monthly
  • Lubricate bearings – Quarterly
  • Change oil – Annually
  • Test resistance of winding insulation per IEEE-43 instructions (DANGER – USE EXTREME CAUTION!) – As required by IEEE

IMPORTANT SAFETY PRECAUTIONS

Pump parts, tools, and rigging equipment used in installing pumps are heavy and may easily cause personal injury if dropped or carelessly handled. The normal precautions and safety rules associated with the erection of heavy machinery, the use of power equipment, manual lifting, and handling of tools must be observed in the installation of this pump.

Do not work under a heavy suspended object unless there is a positive support under it to stop its fall in event of sling or hoist failure. Disregard of this warning could result in grave personal injury.

Before opening the conduit box of an electric motor, be certain that the current to the motor is shut off and the breakers are locked out. An electrical shock from contact with live motor leads can be fatal.

The motor canopy (cover) must be in place when the pump is in operation. If exposed, rotating parts below this cover could cause grave personal injury.

Petroleum-based cleaning solvents are flammable. Smoking by personnel in the vicinity of these solvents is extremely hazardous and must not be permitted.

Also, in many areas, the use of these contaminating and hazardous solvents is illegal. Consult the local EPA/Air Quality officials for instructions.

The pumps described in this manual should not be installed in any manner except as specified herein, and must not be operated at speeds, capacities, pressures, or temperatures other than those specified on this the order.

These pumps must not be used to pump any fluid other than those specified for the order.

Violation of this warning will void the manufacturer’s warranty and may result in serious property damage or grave personal injury.

Sources

About Cal-West Rain

For over 30 years, CalWest Rain has provided leading growers and ranch managers a broad range of irrigation design services, installation/construction services, pump and well services, automation and control systems, as well as maintenance and repair services for all aspects of custom water delivery for agricultural applications. To learn more, contact Cal-West Rain in Kerman, Paso Robles or Hanford or call 559-846-5326.