Pepper Maintenance Canada
Interpreting the Risk
Explanation of Risk and Vibration Levels in Data
1. Warnings are not necessarily problems that need attention. They are used as signals to the analyst that a problem may exist. This machine point needs a closer look at the spectral data. It may or may not require action by the customer.
2. When “raised floor” is indicated, it is a precursor to bearing failure as it indicates looseness within the bearing and races and is one of the last stages of bearing failure. The signal does not return to the x axis and lifts all the way along to high level frequencies.
3. Haystacking is an earlier indicator of impending bearing problems and appears as a pyramid shaped signature at very high frequency ranges (above the 180,000 cycle range minimum). As the bearing nears failure, the haystack moves closer and closer to the rotation frequency of the bearing. The floor is thus kept raised and the bearing moves closer and closer to failure. Race (inner and outer) and rolling element defects are also distinguishable in these signals.
Defenitions
• MONITOR: Abnormalities May be Present
Pay special attention on routine scheduled inspections, (visual and audible) until satisfied unit is stable.
• MONITOR CLOSELY: Abnormalities are Present
Increase routine scheduled inspections (visual and audible) at least double, until satisfied unit is stable. Consult with Pepper Maintenance on next scheduled visit. We do not want to fix a problem that may not exist.
The following risk levels have been established by Pepper Maintenance Systems, Inc.:
RISK LEVELS IN VOLTAGE SYSTEMS 120V- 480V RUNNING ABOVE 75% AMP LOAD
• Low Risk: Corrective maintenance required at next scheduled visit or as time allows.
1◦ – 85◦F or 1◦ – 20 ◦C
• Moderate Risk: Corrective maintenance required as priority scheduling dictates. This should be done within 30 days.
85◦ - 105◦F or 30◦ - 40◦C
• High Risk: Corrective maintenance required as soon as possible. The unit is experiencing vibration levels that are destructive and immediate response is needed. Damage may occur shortly.
105◦ - 125◦ F or 40◦- - 50◦C
• EXTREME RISK: Do Not Delay!! – Immediate response is absolutely necessary. This unit must be shut down immediately. Danger of major failure is imminent.
+ 125◦F or +50◦C
ELECTRICAL LOAD PERCENTAGE VARIATION
Loads less than 75% fla must be understood to be operating at a lower temperature than they would be at a higher amperage load. for this reason, the thermographer may call a phase-to-phase difference of 50◦ an extreme risk rather than a low risk as the above chart indicates, depending upon the amperage load of the operating equipment.
Loads less than 75% fla must be understood to be operating at a lower temperature than they would be at a higher amperage load. for this reason, the thermographer may call a phase-to-phase difference of 50◦ an extreme risk rather than a low risk as the above chart indicates, depending upon the amperage load of the operating equipment.
Bearing, sheave, motor, drive and mechanical risks are determined using one or more of the following factors: environment, comparison to similar application machine history, amount of heat being produced and how far it flows, and experience.
Consult “nuts and bolts of monitor” on resource section of this website in white papers for further information or call pepper maintenance, inc. at 866-359-4016.
RISK LEVELS IN VIBRATION ASSESSMENTS
• Low Risk: .10-.25 in/sec./ g’s are 1 and under in acceleration
• Moderate Risk: .25-.35 in/sec./g’s are 2 and under in acceleration
• High Risk: .35-.6 in/sec./g’s are 3 and under in acceleration
• EXTREME RISK! .6 in/sec and above./g’s are 5 and under in acceleration
• No level assigned: Nothing in the data appears to be abnormal; service unit as usual
Be aware that risk assessment is more complicated than the above would indicate. These are only guidelines and the levels are subject to the ability of the machine to tolerate the forces being seen. However, there are very few applications where these levels do not apply.
Source: https://www.peppermaintenance.com/inspection-process/risk