Devices track vibration issues, smooth machine operations
Determining early when motor components are out of alignment is crucial to preventing unexpected machine shutdowns. Just the normal vibration of machinery during operation can cause bearings or other parts to work themselves loose. By catching these problems early, technicians can make repairs on the plant’s maintenance schedule before a problem becomes critical and leads to machine failure.
Fluke, Balmac and IMI Sensors are among the companies offering devices to enable machine operators and plant managers to measure machine vibrations and diagnose problems themselves. Plant managers can choose from route-based testing, which involves technicians taking semi-monthly, monthly or quarterly readings on different machines throughout the plant, or continuous monitoring with sensors permanently attached to the most sensitive equipment for ongoing analytics. The meters are suitable for use with chillers, fans, pumps, compressors, blowers and gearboxes.
FLUKE METERS DIAGNOSE MULTIPLE ISSUES
John Bernet, mechanical application specialist for Fluke, likens using the company’s 805 vibration meter to seeing a nurse before visiting the doctor. The 805 can diagnose many problems with motors and bearings that line operators or technicians can fix themselves. “If you test monthly, you’re not likely to miss anything. If you test only once or twice a year, you’re likely to be blindsided.”
The meter measures overall vibration, providing a four-level scale in the low frequency range from 10 hertz (Hz) to 1,000 Hz for acceleration, velocity and displacement, and in the high-frequency range (4,000 Hz to 20,000 Hz) to identify bearing faults.
“We designed it based on the need that we saw in the industry to provide the operator with more than just a number,” Bernet said. “In the past, the operator had only two devices — a low-level analyzer and a vibration pen that the user would press into the machine and get a number. But the operator would have no information on what that number would mean. A certain number on a hydraulic pump would be good, but the same number on a screw compressor would be bad.”
While vibration pens might show different readings depending on the amount of force the operator used in applying the device to the machine, the 805 meter corrects for differences in the angle and force applied, Bernet said. The device includes additional hardware, such as cables, for hard-to-reach locations.
Users can export results to Microsoft Excel through a USB connection, then track trends through built-in templates and plot graphs and compare the readings to industry standards.
Most operators can learn to use the device with little or no training, Bernet said.
In the past year, Fluke has added the capability to share the metered information over the Internet via the Fluke Connect app. Using a smart phone, an operator can connect directly with the AutoRecord feature to automatically capture all relevant data, and see the vibration data history of each machine recorded with the Fluke EquipmentLog.
For vibration anomalies that need more research, the Fluke 810 is a more comprehensive diagnostic device that provides on-board identification and location of the most common mechanical faults, such as misalignment, imbalance or loose bearings, with repair recommendations as well as real-time tips and guidance for new users.
The 810 features a triaxial accelerometer to reduce measurement time by two-thirds compared to a single-axis device, as well as databases of similar machines of similar sizes to enable the user to determine if the reading represents a slight, moderate or extreme problem.
The machine is likely OK if vibrations are slight. If moderate vibrations are detected, technicians should check the machine more regularly. If, on the other hand, the vibrations are extreme, the machine should be shut down as soon as possible for repair, Bernet said. The diagnostic tool also includes recommended fixes for most imbalance, misalignment and wear issues, which account for 80 to 90 percent of machine problems, according to Fluke.
The 810 can diagnose most problems; when the issue is too complex for the device, it’s time to call in a specialist, Bernet said.
BALMAC DELIVERS VELOCITY DISPLACEMENT MEASUREMENTS
Balmac’s 200 series of hand-held vibration meters measures vibration trends in terms of velocity, displacement and acceleration. The higher the measurement, the more likely the machine is in need of repair, Balmac VP Steve Crawford said. The meters can be used to take measurements at one or multiple points of a machine, with the user recording readings.
The velocity, measured in inches per second, shows the rate of change of displacement. Velocity is more closely correlated to the destructive forces generated in a machine than either displacement or acceleration, according to Balmac. Velocity readings reveal more about vibration at machinery speeds ranging from 180 to 20,000 revolutions per minute (rpm).
Displacement is the distance the part moves in mils. The operator must know the normal rpm of the equipment to establish a vibration limit for displacement. Acceleration is the rate of change of velocity read in G-forces. According to Balmac, G-forces are useful when measuring very high frequency vibrations, such as signals generated in rolling-element bearings or gear trains.
The 200-series meters come with a manual and calibration certificate, a guide to vibration management and an information wallet card so that even an inexperienced user can quickly identify the problems that most commonly cause high vibration readings. While users can carry the hand-held meters from machine to machine, for some of the most critical machines, a company may want to have a vibration transmitter mounted permanently for continuous readings. Most plant operators, though, opt for the portable devices because they can be used for several machines, not just one.
“Companies are looking to shed costs wherever they can,” Crawford said.
With Balmac’s 140 and 191 series of vibration transmitters, companies have access to continuous vibration readings on their most critical fans, motors, pumps, compressors and other general- purpose machinery.
Companies can use the transmitters in conjunction with vibration switches to provide automated alarms or shutdowns when vibration reaches certain levels. Balmac offers a range of switch sizes to fit different plant and machine configurations.
With a vast array of accelerometers designed for different sizes and types of machines, IMI Sensors can provide plenty of data. That has an upside and a downside, product manager Meredith Christman said. An experienced operator who has plenty of data can accurately diagnose a machinery problem, but someone with little experience can be overwhelmed. This can be a challenge, Christman said, because many industries are facing skills shortages as older workers retire.
To meet these needs, IMI offers low-cost accelerometers and precision accelerometers that can be used with data collectors to measure the vibration of different devices. The accelerometers, which provide measurements about AC voltage and amplitudes at a specific frequency, can connect through a switch or junction box for route-based collection.
The precision accelerometers have tighter tolerances on some specifications such as sensitivity and frequency ranges.
IMI’s vibration transmitters are loop-powered 4-20 mA output sensors, most commonly used for vibration monitoring with a control system.
IMI offers a pair of vibration switches that can be programmed to set off an alarm to notify a technician of a problem or to automatically shut down a machine.
Phillip Britt, contributor
Plain City, Ohio, 614-873-8222,
Everett, Wash., 425-347-6100,
Depew, N.Y., 716-684-0003,