Fan Bearing Lubrication Issue Identified Through the Integration Of Multiple Technologies

Diagnosing Issues With Multiple Technologies

We investigate how using multiple technologies in a predictive maintenance program increases the prevalence of accurately diagnosing issues.

Background and Problem

During an Electrical Infrared (IR) scan at a health treatment facility, the breaker for a fan assembly was noted as having a much higher difference in temperature (Delta-T). This led to Allied Reliability initiating an investigation to determine the following:

  • Why is the breaker so hot?
  • Is it an electrical problem or a mechanical problem?

This particular fan is used to circulate exhaust air throughout the “B-Wing” of the facility, thus creating a constant intake of fresh air to the facility via draft vents. Fresh air CFM requirements are critical in maintaining compliance with regulatory code. If this machine suffers a functional failure, it is unlikely to cause immediate diversion of any departments; however, regulatory compliance will cease.

Figure-1-Fan-AssemblyFigure 1 Fan Assembly

The Investigation

The first thing we decided to do during our investigation was to perform additional vibration readings on the bearings of the fan. This is a very large fan and, unfortunately, the only accessible bearing was the inboard fan bearing (a sleeve bearing). The outboard fan bearing was inaccessible and inside a confined space.

However, there was a small hole, 3/4 inch diameter, in the housing of the fan towards the outboard end of the fan assembly that allowed us to see the outboard bearing. Figure 2 shows a thermal image of the outboard bearing taken through the hole in the fan housing. This was a great help in determining the cause of the issue because we were able to see the type of bearing. It was a large DODGE Double-Interlock Tapered Roller Bearing, which we noted also looked dry around the seal area. This led us to believe it was a lubrication issue.

The inboard fan bearing (Figure 3) is a different type of bearing. It is a sleeve bearing and is the only location where we could obtain vibration readings for the entire fan unit. Vibration readings were taken from the inboard fan bearing before any corrective actions were performed (Figure 4). The infrared image in Figure 5 is of the EX-19 breaker inside panel 9200-DP-RPC before any corrective actions were performed.

Figure 2 Outboard Bearing.png
figure-bearingFigure 3 Inboard Bearing Location
figure-graphFigure 5 Breaker Panel
Figure 4 Inboard Bearing Vibration Readings

The Solution

The fan was locked out, confined space permits were issued, and the lubrication technician entered the area of the fan outboard roller bearing. He purged the bearing using the supplied procedure and filled it using white lithium grease. The bearing required almost a full tube of grease; the bearing was completely empty of lubrication and needed it severely. The unit was then unlocked and the quality check process begun.

Vibration readings were taken again after corrective actions (Figure 6). The vibration amplitude was reduced in half and a major reduction in “noise floor” energy was also noticed.

Next it was time to see if the associated electrical breaker was reading less of a current draw from the fan. Figure 7 shows the infrared findings of the breaker after running for at least an hour; less than a 1 degree Delta-T currently exists.

Figure 6 Inboard Bearing Vibration Readings
Figure 7 Breaker Panel

Using multiple technologies in any Predictive Maintenance Program allows the user to find more faults with more certainty. Had we not noticed the electrical high amp draw using infrared, we might have assumed everything was fine with the fan bearings due to no alarms being exceeded. However, it turns out there was an obvious lubrication problem.

Figure 8 shows an overall vibration amplitude trend from the fan assembly’s inboard fan bearing vibration data. The lowest points in the trend graph show were the vibration amplitudes bottom out as a result of lubrication activities over the last year. This vibration data could also be used to demonstrate evidence of correct lubrication frequencies – or to set optimal lubrication frequencies if the data indicated that an improper frequency was being used.

Figure 8 Fan Inboard Bearing DataFigure 8 Fan Inboard Bearing Data

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