Uptime Magazine - October/November 2008 - (Page 68)

Examining the operating shapes gives the analyst additional insight into the root cause of many vibration related faults. Combining this analysis with an Experimental Modal Analysis is very effective in ruling-out suspected machinery problems associated with resonance. along with the seemingly adequate resonant margin, was another indication that this system was unusual. The whirling orbital motion in Figures 5 and 6 suggested that the excessive vibratory response was NOT due to resonant amplification. ODS animations near a resonance will typically correspond to the linear mode shape. The animations suggest that the pump rotor (extended below deck) was driving the response in the motor. A possible reason for this is excessive clearances in the seals and “spider” bearings that support the rotor. Significant leakage from a problematic seal in this pump tends to support the theory that radial clearances are larger than desired. Additional animations without the motor (Figure 6) more clearly show the whirling motion in the motor standoff support structures. The final animation in Figure 7 shows an isolated view of the support base plate structures. The foundation amplitudes suggest that vibration levels are higher than normal; however, the dense measurement mapping confirms that Analysis & Conclusions In this analysis, the P4119 pump indicated some unexpected characteristics. Typical resonance amplification will induce a linear response in the direction of, and similar to the mode shape defined in the EMA. The closer the driving force is to the natural frequency, the more mode shape resemblance in each animation. This characteristic was not found in the ODS animations. In the P4119 pump operating shapes, a “whirling” or “orbital” ODS animation motion was noted. This visual response, Figure 4 – Animation Model in ME’scope Software SERIES 686B SMART VIBRATION SWITCH Now Get the Reliable Protection of an Electronic Vibration Switch for the Low Price of a Mechanical Switch! New Series 686B smart vibration switch is now more cost-effective than ever and fully USB programmable from any PC. The user can easily set delays, thresholds, normally open or closed, latching or non-latching, and other operational parameters. With two-wire operation, it is simple to install, and a drop-in replacement for troublesome mechanical switches. With Remote Reset AnywhereTM, you no longer need to climb your cooling tower to reset a tripped switch. Simply install the reset button at any convenient location in the existing two-wire loop for easy and safe access. This unique, low cost, switch replaces most mechanical or electronic switches. Precision measurement of vibration velocity Power on, startup, & operational, delays ■ Universal 24 to 240 VAC/DC power ■ SPST 0.5 A contact with easy extension to DPDT@10A ■ Hermetically sealed for harsh environments ■ Optional MAVTTM automatically sets alarm level ■ ■ Anothe IMI Sen r sor Industry s Exclusiv e! © 2008 PCB Group, Inc. PCB ® and IMI® are registered trademarks of PCB Group, Inc. SensorLine is a service mark of PCB Group, Inc. Remote Reset Anywhere and MAVT are trademarks of PCB Group, Inc. Class 1, Div. 2, Groups A,B,C and D and Ex nL IIC T3 & AEx na IIC T3 CSA certified for use in hazardous areas Call us today to learn more about the Smart alternative to mechanical vibration switches! Toll Free in USA 800-959-4464 ■ 24-hour SensorLineSM 716-684-0003 E-mail imi@pcb.com ■ www.imi-sensors.com/UPT4 ISO 9001:2000 Certified ■ AS9100:2004 Certified 68 october/november 2008 http://www.imi-sensors.com/UPT4 http://www.imi-sensors.com/UPT4

Table of Contents Feed for the Digital Edition of Uptime Magazine - October/November 2008

Uptime Magazine - October/November 2008 Contents Upfront Upclose: An Asset Management Oasis in the Desert Information Technology: Streamlining Through Simplicity Lubrication: Phases for Framing a Solid Foundation Infrared: Do Your Homework Before You Buy Maintenance Management: Get It Together by Getting Together Motor Testing: Key Elements in Motor Decision Making Precision Maintenance: Shedding Some Light on Tolerances Reliability: RCM & the Mortgage Meltdown Ultrasound: A Multidimensional Tool Vibration: The Whirling Pump Mystery, Solved with ODS Upgrade: Are You Looking in the Right Place for Your Wear Debris?

Uptime Magazine - October/November 2008

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