An Alert Operator Is a Safe Operator

April 24, 2008
Maintaining a good work environment can contribute to a safer plant

I had left the control room at a plant in the Philippines for only a few minutes, going into an adjoining lab to review calibration standard tests, when I heard an anxious voice on the radio — I dashed back to find that the operator had fallen asleep. Discussions with operators the next day revealed that they were working 12-hour shifts with a day off every two weeks. On that day off, some of my crew had been traveling halfway across Luzon to visit family, going without sleep the following day. This had been happening for two months.

So, how did I improve this situation? I changed the rules: first, by allowing operators to sleep in shifts in the nearby electrical room and second, by installing card games on the spare computer. I wanted to improve the operators’ computer motive skills and keep them mentally alert. When we did the commissioning work again several months later, my crew was up to the challenge.

Granted, this situation was a bit drastic. How can you, a process engineer, improve the performance of your operators? Take a look at your control room. Is it too hot, too cold, dry, damp or dusty, noisy, too bright or dimly lit? Are there too many alarms? Is there enough workspace? Are the screens easy to follow with a minimum of extraneous bells and whistles? Is there an area where people can congregate that doesn’t interfere with the control board operators? Carefully weigh all of these factors.

The best layout I’ve ever seen was at Millennium Chemicals in Ashtabula, Ohio, a plant originally built by DuPont back in the 1960s. The control monitors filled a broad semicircle around the operators. There was plenty of space between the keyboards for operators to work. Natural light streamed in from windows; a few small lamps lighted the desk space without taking away from the computer screens.
There was a sizable open space in the back. A large table there held equipment and supplies operators would need when they geared-up before braving the cold. A separate table contained two view-only screens. Operators, engineers and visitors could congregate in the back, calling up faceplate information on those screens without interfering with the board operators. None of this would have worked without strict discipline; talking at a whisper was allowed but nothing louder.

The engineer’s station, or doghouse, which permits normal operations to continue while engineers upgrade software undisturbed, was located behind the control room with the motor control center (MCC) in between. The MCC had a desk and chairs for the electricians. Each area was isolated with solid doors.

The worst layout I’ve ever seen was at a bio-products facility: operators were crowded together, bumping shoulders with each other and people at the room exits — control screens clogged the center of the room. Overheating of electronics was a constant problem. Unlike Millennium, the room was dirty, dank, dark, sticky and unpleasant; the frequency of operator error was much higher. The MCC was located 100 yards away and there wasn’t a doghouse.

Improving physical conditions, such as by putting in dehumidifiers and more comfortable chairs, can help, but isn’t enough.

Attacking nuisance alarms will reduce the level of stress on operators. Some industry experts recommend installing an expensive monitoring program to track nuisance alarms. A more economical and perhaps more effective approach might be to hold regular meetings with the operators to identify where faceplates fall short. Avoid cluttering displays with status alarms — e.g., a full tank or stopped pump — and instrument malfunction alarms. Relegating status alarms and malfunction alarms to beep-once-log-then-silent mode will reduce stress. Reassess the status summary and alarm summary faceplates, the familiar replacement for the old “light box.” Ideally, these “billboard” displays should provide a view of the health of a process at a glance. Instead, too much data are added or alarms are mixed in. Develop a separate alarm summary; it should include a color scheme and, if possible, should segregate alarms from alerts and define alarms according to categories, e.g., instrument failures, temperature, pressure, flow and so forth.

The Alarm Management Handbook” by Bill Hollifield and Eddie Habibi provides additional information on nuisance alarms. Ian Nimmo has also been a standard bearer in the crusade to improve the operator environment; see, for instance, Distributed control systems: Rescue your plant from alarm overload and Accurately determine console operator workload.

While coffee can assure physical readiness it won’t keep people mentally keen. When I was tuning burner controls, which can take several hours, I brought along a book. Ironically, I was reprimanded for reading. Since that time, I have seen radios and books allowed in control rooms to break the monotony. If knitting helps keep an operator keenly focused and able to respond to an alarm, I’d recommend knitting classes for interested operators.

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