As this overview of technologies points out, today’s maintenance technicians and operators have access to capabilities that were previously limited to monitoring specialists.
Featuring streamlined designs and improved factory-floor functionality, next-generation condition-monitoring instruments and devices stem from advances in digital technology and electronics. Typically lightweight and portable, they require no special technical skills to operate. Personnel can, thus, become proficient in their use with little training and after only an hour or two of practice.
These innovations include durable vibration analyzers, portable lube-analysis kits, versatile stroboscope/tachometers, non-contact thermometers and many more. Leveraging such tools, users can perform a range of basic monitoring activities and obtain valuable data on operating conditions with regard to the following issues:
Maintenance technicians and machine operators can now take vibration readings during routine inspections using powerful handheld analyzers. One type, for example, takes both overall velocity and enveloped acceleration readings at each point on targeted machines. The velocity vibration measurements are automatically compared with pre-programmed ISO standards, triggering an alarm when the measurements exceed the guidelines. The enveloped acceleration measurements are compared with established bearing vibration guidelines.
This analyzer is extremely durable and rated for use in industrial environments. Weighing less than a half-pound, the device fits in a pocket or on a tool belt and can be easily carried on inspection rounds.
Monitoring oil samples in the field has long been standard practice, but grease analysis has usually proved difficult. The introduction of modern grease-analysis kits, however, makes quick evaluation more feasible and affordable than in the past.
In a recent case, a pulp and paper mill in Brazil implemented on-site grease analysis to speed up decision-making and reduce costs. The facility already had a fully functioning lube-analysis program in place. Grease samples were collected and forwarded to an independent laboratory at a cost of almost $60 per sample. Testing was completed in about a week. But the turnaround time caused delays and affected plant operations.
Looking for a solution, the mill’s lubrication manager acquired two portable grease-test kits to let in-house personnel analyze fresh grease on the spot. The kits contained three different tests of grease quality: consistency, oil bleeding and contamination. No special expertise was needed to perform the tests—and they each required only 0.5 grams of grease for sampling. The testing was able to clear some samples immediately and identify others that required lab analysis.
This on-site analysis program helped reduce the number of samples sent out for testing by 25%, which, in turn, helped cut overall costs. It has also given the mill greater control over lubrication decision-making.
Motion and speed
Technicians monitoring the motion of operating machines can turn to portable stroboscopes that “freeze” the movement of rotating or reciprocating machinery like fan blades, couplings, gear wheels and belt drives. Doing so allows machines to be safely inspected while they are running.
The latest offerings include a new instrument that functions as a dual stroboscope and tachometer (see Fig. 1). The device has a stroboscopic flash rate of nearly 300,000 pulses per minute, enabling it to monitor most high-speed applications. Its ergonomic design allows users to set the flash rate in seconds. The versatility of this device is enhanced by a remote optical sensor that allows the tool to operate as a tachometer. In this mode, the instrument measures rotational speeds up to 300,000 rev/min with an accuracy of +.01%.
Fig. 1. This versatile stroboscope monitors the motion of rotating machines and, with the help of its optical sensor, can operate as a tachometer. (Source: SKF USA Inc.)
There are a number of new-generation devices for remotely sensing heat and thermal energy. These include noncontact infrared thermometers that provide accurate measurements from a distance. They incorporate an infrared detector to sense thermal energy radiating from operating machinery. The detector produces a signal that is translated into a reading on the device’s display screen.
One such thermometer has dual-laser sighting to precisely define the area being measured. It senses temperatures ranging from -60 to 1000 C (Fig. 2). Users can program this instrument to emit audible alarms at specified high or low temperatures.
Fig. 2. A non-contact infrared thermometer makes accurate measurements by sensing thermal energy radiating from machines. (Source: SKF USA Inc.)
Another heat-sensing technology, thermography, has also been improved—and become more affordable—over the last decade. Thermal cameras with imaging capabilities allow technicians to visualize machine hot spots from a safe distance. Some cameras can even operate unattended with images taken and saved at regular intervals.
Air leaks in HVAC systems and other applications produce high-frequency sounds due to turbulence near the leak site—sounds that can be pinpointed by ultrasonic detectors. One such instrument has a sensor mounted on a long flexible tube, allowing access to hard-to-reach areas. It helps guide the operator to the loudest point, revealing the leak’s location. This detector is compact enough to use with one hand and requires no special training.
There are also handheld instruments for measuring noise levels in industrial facilities. The instruments, usually battery-operated, pick up sound using built-in microphones and indicate the sound level in decibels. MT
Based in Ontario, Canada, Paul Michalicka is a North American Area Manager for maintenance products, SKF USA Inc.