Mixer Drive Troubleshooting
|Trouble||What To Inspect||Action|
|Overheating||1. Motor Overload||a) Determine if the density and viscosity of the process liquid is the same as originally specified
b) Is liquid level in tank above minimum operating levels, i.e. 2.5 times the propeller diameter above the axis of the mixer shafts? If not, cavitation may be taking place.
c) Are there any objects inside the tank impeding the propeller flow?
d) Check that shaft rotates freely by hand.
e) Check for mechanical or electrical problem. Correct supply/wiring. Check motor nameplate details are correct.
f) Ensure no jet mixers or pump inlets are creating flow over the mixer propeller. Ensure no large items impede the flow path of the propeller.
|2. Belt slip/tension||a) Inspect belt for damage and replace if needed. Reinstall and tension belt per Outline Installation Drawing (OID) in Section 14.|
|Noise||1. Excess Turbulence||a) See Overheating Reference 1b, 1c, 1f|
|2. Worn Bearings||a) On old units that have operated for long periods; check condition of bearings.
b) Check bearings for excessive grease loss; replace if required.
|Unit not rotating||1. Unit Jammed||a) Lock out, tag out, and disconnect power and stop internal tank flow if present. Inspect for damaged seal, worn/damaged bearings, belt slip/tension. Verify free rotation by hand prior to reconnecting power.|
|2. Belt slip / tension||a) See Overheating Reference 2a|
|Vibration||1. Check set screws||a) Check tightness of set screws on Bearing Sleeve. All set screws should be held with Loc-tite #246 and a jam nut.|
|2. Excess Turbulence||a) See Overheating Reference 1b, 1c, and 1f.|
|3. Belt slip/tension||a) Check belt tension chart on the Outline Installation Drawing (OID) in Section 14.|
|4. Worn Bearings||a) See Noise reference 2.|
|5. Bolt Tightness||a) Check the tightness of all fasteners (see torque value chart in the Recommended Torque Values in Table 1).|
|6. Mixer Support Structure||a) Is the tank nozzle/manhole and tank shell rigid enough to support mixers?
b) There could be a harmonic from the tank mounting exciting the Tank Mixer.
|7. Mixer Support Sling||a) Is the mixer support sling correctly tensioned? (Reference Common Parts drawing)|
|8. Damaged Shaft or Propeller||a) Has the shaft or propeller been damaged in transit, storage or installation? Is it possible for the propeller to have been damaged on any in-tank projectile? If propeller is site fitted, is it correctly fitted?|
|9. Swivel Locking Arrangement||a) Swivel-Angle Units Only – Is the swivel locking mechanism locked tight? Also check for wear on locking mechanism pins.|
|10. Autoswivel Brake||a) Ensure brake is set snuggly enough to prevent excess vibration but does not strain the actuator system.|
|11. General||a) If vibration problem cannot be corrected take frequency readings on displacement (in pk-pk) and velocity scale (in/sec peak) and report them to Philadelphia Mixing Solutions.|
|Trouble||What To Inspect||Action|
|Noise||1. Coupling Wear||a) Check input coupling for wear. Replace if worn|
|2. Bearings and gears properly lubricated||a) Shut off mixer and check the oil level.
b) Oil must be the grade specified in the lubrication instructions. If it is not, flush mixer drive and refill with the correct grade of oil
|3. Mounting & coupling hardware||a) Be certain that all mounting and coupling hardware is tightened to the correct wrench torque.|
|4. Mixer support structure||a) Does the mounting arrangement for the mixer provide sufficient support to prevent wobbling or vibration of the assembly? See Outline Installation Drawing for criteria.|
|Vibration||1. Agitator shaft||a) Agitator shaft should not be bent.|
|2. Critical speed||a) If the shaft and/or impellers are supplied by others, check for a critical speed condition. Vibrations can occur through a particular speed range.|
|3. Steady bearing (if applicable)||a) Has excessive wear occurred to the steady bearing?
b) Is the bearing securely bolted to the vessel and is it properly aligned?
|4. Inspect hardware||a) Is all blade hardware (and extension arm hardware, if applicable) properly torqued? Including agitator shaft couplings and mounting hardware?|
|Oil Leakage||1. Plug at drain and standard pipe fittings||a) Apply pipe joint sealant, or equal, and tighten fittings.|
|2. Housing and caps||a) Tighten cap screws or bolts to proper torque. If not entirely effective, remove housing cover and caps.
b) Clean mating surfaces and apply new sealing compound/gasket.
c) Ensure mounting surface is level and is not distorting mixer housing.
|3. Mixer output shaft||a) Has the recommended oil level been exceeded?
b) Check oil level. Drain oil to the correct level.
|4. Breather||a) Breather must be open and clean|
|Cannot read oil level||1. Oil Level Window Glass||a) Drain gear oil, remove sight glass, clean glass surfaces using solvent. Replace sight glass and refill mixer oil to correct level.|