February 07, 2011

Dear Control Engineering: I was reading the article Device Diagnostics and Asset Management. Please explain Storey's final statement in a little more detail.

At the end of the article, Storey is offering a practical way to know if your program is successful. His comment assumes that you are using diagnostics, at least to some extent. His point is that if you sift through the diagnostic data after something has failed, your program is not working as it should. That situation is like a driver who has just hit another car in an intersection going back to see if there was a stop sign that he should have seen.

Storey's indicator of a successful program is when you can show that you avoided a problem thanks to diagnostic information. Here's an example: You have a pump in your plant and your maintenance procedure for that device says that you should replace the bearings every 2,000 hours of operation. That procedure works, but in reality bearings can often last longer than that, but at the same time, if the installer is careless, they may fail after only 1,500 hours. If you have a sensor that can diagnose the bearings' condition, you will know exactly when they are beginning to fail early enough to take appropriate measures. That way you always get the maximum life while avoiding failures under load. You will replace the bearings when they need it, not according to the calendar.

Take the survey that goes with the article and let us know where your company's maintenance program is.

Peter Welander, pwelander(at)cfemedia.com