Wireless transmission cuts condition monitoring costs

Industrial facilities are under increasing pressure to improve reliability while cutting the cost of maintenance manpower and materials. Studies show that leading facilities spend less, yet have higher scores on critical key performance indicators such as overall equipment effectiveness (OEE), mean time between failures (MTBF) and maintenance cost as a percent of production.

We know the key to spending less and getting more is to do the right thing at the right time, a nice way of saying, “only what’s needed, at the last minute.” But what, exactly, is needed? And how much time do we have? The science of condition monitoring (CM) was developed to answer those questions.

“Keeping a better eye on assets can mean the difference between success and failure”

- Paul Studebaker, CMRP, Editor in Chief

But CM technologies such as oil analysis, ultrasound, thermal imagery and vibration require their own investments in installation and labor. Where it’s appropriate, wireless data transmission empowers condition monitoring by reducing those costs. This increases paybacks and allows facilities to apply more effective condition monitoring to more equipment.

Keeping a better eye on assets can mean the difference between success and failure. “On a global scale, in North America we have some of the world’s oldest facilities competing with brand new plants in China,” says Bob Karschnia, vice president, wireless, Emerson Process Management (www.emersonprocess.com). “Products can be sourced all over the world. Older plants need to monitor and control their processes better, and they can do this with wireless.”

The Holy Grail

Wireless might be an option for any condition-monitoring technology that must transmit data, but most of our experts used vibration monitoring as their example. Vibration has traditionally been split into high-end protection systems used only for expensive, critical machinery like turbines, and portable equipment for route-based monitoring.

“Critical machinery gets $100,000 protection systems,” says Bart Winters, reliability solutions manager, Honeywell (www.theoptimizedplant.com). “Less critical machines might get $20,000 wired systems, and everything else is manually probed at intervals, typically weekly or monthly. That costs $600 to $11,000 per year, depending on its location and how often it’s done, and it’s not frequent enough to always protect the equipment.”

We would like to take measurements on more equipment, more often, but, “Wired systems cost too much to install — typically 10 times the transmitter cost to put one in,” says Todd Reeves, product manager, machinery health management, Emerson Process Management. “It becomes a big capital project that’s hard to justify. Maintenance guys fight the emotional battle and the economic battle, but it’s too hard so they just use routes and hope things don’t break between rounds.”

So, what the people need is a lower-cost, lower-labor approach, says Mark McGinn, managing director, SKF Condition Monitoring (www.skf.com). “The holy grail is a wireless system that competes with both portable and traditional wired systems by reducing the manpower costs of route-based monitoring, and the equipment and installation costs of traditional online systems.”

Define “wireless”

When you say wireless, most people think of wireless sensors. These are becoming commonly available for simple process variables such as temperature, but have cost and battery life issues when used for complex data collection. “There are a few out there, but low power equals low bandwidth, which is a problem with vibration,” says Jonathan Hakim, president, Azima DLI (www.azimadli.com). “You can get overall vibration levels and scalar values, but not spectra.”

Other experts say the cost of a reliable, capable sensor is still too high. “If a route-based system costs $125 per point, it’s hard to justify a wireless transducer,” says Tom Millis, manager, global reliability services, Timken (www.timken.com). “The application for a $100 sensor has to be simple and steady-state, like some pumps.”

The time will come. “Two years ago I said the killer app was going to be the low-cost, ubiquitous, wireless condition-monitoring sensor to monitor behavior with model-based predictive systems. Life would be good,” says Hesh Kagan, managing consultant, Invensys Process Systems (www.ips.invensys.com). “But the low-cost condition-monitoring sensor hasn’t occurred. So give it another two years.”

Meanwhile, we’re left with two viable configurations: battery-powered, wireless sensors that transmit limited information and alarms (see sidebar, “A paper case”), and conventional sensors wired to a device near the machine that transmits wirelessly around the facility. The latter offers the opportunity to gather data more often and more accurately than route-based monitoring, as well as access to equipment in remote or unsafe locations.

The walkaround without the walking

Wireless can connect wired systems into a wireless network so you can do the walkaround without the walking. “Assets that did not justify wired systems but have a history of failures that affect production and happen between walkarounds offer an ROI on closer monitoring,” says McGinn. “Wireless has a lower installation cost that can let you address pumps, fans and gearboxes in this category.”