Vibration spectrums collected from motors, blowers, and pumps, are pictures of the amplitude     of a vibration compared to a range of frequencies(speeds). There are probably an infinite number of parameters to program the meter to measure the vibration, and everyone who looks at(analyzes) the data will do so differently. Oftentimes with completely different diagnosis, and recommendations. The ability to analyze the data will depend on experience with that type of equipment. Don't have an engineer who specializes in analyzing data collected from high speed fans, or helicopters, to figure out what is wrong with the drive motor on your sludge pump.

Vibration analysis is probably the best tool you can use to identify and monitor conditions with your rotating equipment. Collecting baseline vibration data when the equipment is new goes a long way to insuring a quick identification of abnormalities with your equipment as it ages. When the unit starts making more noise and vibrating, you call for a vibration analysis. The analyst will identify probable causes, such as shaft misalignment, which has a spectrum that shows the peak vibration at 2x the rotational speed(rpm), measured in the axial direction.

Spectrums for rotor imbalance will show the peak vibration at operating speed, and will be higher in the horizontal plane. But peak vibration at once per rev can also have other causes, such as bent shaft, or worn sleeve bearings. Peak vibration levels at 2x operating speed can also be caused by simple looseness(motor bolts), or soft foot(shaft misalignment), as well as a host of other causes. That is why the type of vibration measurements(spectrums) collected is very important in accurate analysis.

We here at STS collect four different types of measurements that all help to identify the cause, or more effectively rule out a possible cause. One of the key measurements is the bearing condition envelope spectrum which is used to monitor the bearing wear. The higher the value, and the increase in 'noise' in the spectrum, the more the bearing is worn. If properly trended quarterly, or better yet, monthly, the failure of the bearing can be predicted. Is it going to fail in 6 months, or 6 years?

Vibration analysis is a very important tool in your preventative maintenance program. Invest in PM, it will save you money!