Necessary Checklist for Preventive Maintenance of Centrifugal Pumps

All pump manufacturers will supply a manual by listing recommended maintenance procedures needed for their pumps.

However, all routine preventive maintenance practices for sanitary pumps must include checking and monitoring of following items –

  • Bearing and lubricant status

You must monitor the level of lubricant, bearing temperatures and vibration. Lubricant must be clear having no frothing signs. Increased bearing temperature and excessive vibration may indicate imminent problem.

  • Shaft seal condition

All the mechanical seals must show no visible leakage signs. Some amount of packing leaking may be normal, but this must not exceed 40 – 60 drops/minute.

  • Overall pump vibration

Possible bearing failure can always be preceded by change in vibration of bearing. Excessive vibration may result due to change in pump cavitation or alignment resonances between pump, its foundation, or valves located in suction or discharge lines.

  • Discharge pressure of pump

Slow decrease in pump’s developed head pressure may show that the clearance of impeller has widened. Necessary adjustment of impeller clearance may be needed to restore pump to its desired design performance.

Additional parts examination

Following are few additional parts examinations may be needed:

  • Bearing frame/foot

Check for cracks, rust, roughness or scale. All machined surfaces must be free of erosion or pitting.

  • Bearing frame

Check for dirt on all tapped connections. Clean/chase threads as needed. Remove all loose/foreign material. Inspect passages of lubrication to ensure that they may not be blocked.

  • Sleeve and shaft

Try to inspect for pitting or grooves. Check shaft runout and bearing fits and replace shaft and sleeve in case found worn or if shaft runout is more than 0.002”.

  • Casing

Check for wearing signs, corrosion/pitting. If wearing exceeds 1/8” depth, the casing must be replaced. Check all gasket surfaces for any signs of various irregularities.

  • Impeller

Inspect impeller for any wearing, erosion/corrosion damage. If vanes are found bent or show any wear more than 1/8” deep, then impeller must be changed.

  • Frame adapter

Check for any warpage, cracks/corrosion damage and if any of such conditions is present then replace.

  • Bearing housing

Check for signs of corrosion, wear, cracks or pits. If worn out then replace housings.

  • Seal chamber

Check for cracks, pitting, erosion or corrosion. Also inspect for any wearing, scoring or grooves which might be on chamber face. Change if more than 1/8” deep worn out.

  • Shaft

Inspect the shaft for corrosion or wear out and also straightness.

  • Severe service conditions

In case, pump is used under severe service conditions like highly corrosive liquid then maintenance/monitoring intervals must be shortened.

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