OPERATOR TROUBLESHOOTING

OPERATOR TROUBLESHOOTING O025

  • Some of the pump components are getting too hot. You can smell or feel excessive heat
  • Make sure piping reducers are not installed upside down.
  • If a storage or head tank is being filled from the bottom rather than the top, the pump head is changing and could cause seal problems as the pump operates off its best efficiency point.
  • Listen for unusual noise indicating cavitation or water hammer.
  • You can hear and feel vibration
  • You can detect leakage coming from the stuffing box or seal gland. Make sure the leakage is coming from the pump and not a leaking flange above.
  • The pump is giving off a bad odor. The product may become too hot or the bearing oil is overheating.
  • The pump is running dry, causing it to loose suction. A tank level gage could be stuck, giving a wrong reading
  • The pump is operating off of its best efficiency point to satisfy the system needs. This causes shaft deflection
  • The pump is being started with the discharge shut, or severely throttled to save electricity during the start up procedure. This will move the pump off its best efficiency point and could damage the mechanical seal. Starting with the discharge valve wide open will also move you off the best efficiency point and may also trip the motor circuit breaker because of high amperage.
  • The pump was not vented properly at start up. It is losing its suction head. You cannot vent a running pump because centrifugal force will throw the fluid out leaving the air trapped inside.
  • The pump is surging
  • If the pump is in an awkward or hazardous location, you will want to use a C or D frame adapter to insure good alignment. Be careful using wash down hoses around pumps and motors
  • Don’t let welders use the pump as a ground for their welding rig. You can damage the bearings
  • Has someone painted the pump while it was in place? Sometimes they also paint an outside mechanical seal, restricting the movement of the springs and sliding components.
  • If you change the temperature, concentration, viscosity or, pressure of your product it can shorten the mechanical seal life
  • A motorized discharge valve is changing the system curve
  • A suction valve is being used to control flow. It can cause cavitation problems.
  • If you are pumping a slurry, be aware there is a critical carrying velocity to prevent solids from settling out.
  • The gage readings and tank levels are changing, but they are being ignored.
  • Cleaners are being flushed through the lines that are not compatible with a pump component. The rubber parts (elastomers) in mechanical seals are very sensitive to cleaning chemicals.
  • Pumps are running intermittently without the lines being flushed properly.
  • Frequent starts and stops can cause the fluid to crystallize, solidify, become viscous etc. affecting the mechanical seal performance. This is one of the reasons that most seal failures occur at startup after the pump has cooled down.
  • A sudden power failure can damage the piping.
  • To be a better pump troubleshooter, you must be aware of pump installation recommendations.

Good operating practices will lower maintenance problems. As an example:

  • Do not pump a tank dry.
  • Be sure the tank vent is clear and will not freeze shut in cold weather.
  • Run as close as possible to the pump best efficiency point. You may have to reduce the impeller diameter or change the shaft speed to do this.
  • Be sure to keep any mechanical seal environmental controls functioning when the pump is stopped. These controls include:
    • Flushing the stuffing box with a clean liquid.
    • Heating or cooling the stuffing box with a jacketed pump.
    • Controlling stuffing box pressure with suction or discharge recirculation lines.
    • Quenching to control the seal temperature and to wash away solids outboard the mechanical seal.
    • Using dual mechanical seals and a barrier fluid to prevent a pressure drop across the inboard seal faces.
  • Remember that constant running is easier on bearings and seals. Most seal failures occur at start up because of breakaway friction.
  • Check that you are not running at a critical speed. This is possible if you are controlling pump speed with a variable frequency drive (VFD).
  • If you are pumping a slurry, remember that there is a critical carrying velocity for the pumpage
  • You should convert any packed pump that runs at a negative suction pressure (condensate pumps), to a balanced mechanical seal

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  • On February 16, 2018