Vibration Detectors Transducers and Cables

A variety of monitoring, trending, and analysis techniques are available that can and should be used as part of a total plant vibration monitoring program. Initially, such a program depends on the use of historical trends to detect incipient problems. As the program matures, however, other techniques such as frequency-domain signature analysis, time-domain analysis, and operating dynamics analysis are typically added. An analysis is only as good as the data used, therefore, the equipment used...

Machinetrain Monitoring Parameters

This chapter discusses normal failure modes, monitoring techniques that can prevent premature failures, and the measurement points required for monitoring common machine-train components. Understanding the specific location and orientation of each measurement point is critical to diagnosing incipient problems. The frequency-domain, or fast Fourier transform (FFT), signature acquired at each measurement point is an actual representation of the individual machine-train component's motion at that...

Absolute Fault Alarm

Ird Vibration Chart

The third limit, the absolute-fault alarm, is the most critical of the alert alarm limits. When this limit is reached, the probability of catastrophic failure within 1000 operating hours is greater than 90 . Absolute-fault limits are typically based on industrial standards for specific classifications of machinery. Generally, these standards are based on a filtered broadband limit and are not adjusted for variables such as speed, load, or mounting configuration. However, vibration amplitude and...

Trending Analysis

Ird Vibration Chart

Long-term vibration trends are a useful diagnostic tool. Trending techniques involve graphically comparing the total energy, which is the sum of the frequency components' amplitude over some consistent, user-selected frequency range (i.e., FMIN to Fmax), over a long period of time to get a historical perspective of the vibration pattern. Plots of this sum against time (e.g., days) provide a means of quantifying the relative condition of the monitored machine (see Figure 14.1). Most predictive...