Most often the major usability problem is that there are too many alarms annunciated in a plant upset, commonly referred to as alarm flood (similar to an interrupt storm), since it is so similar to a flood caused by excessive rainfall input with a basically fixed drainage output capacity.
Poor alarm management is one of the leading causes of unplanned downtime, contributing to over $20B[citation needed] in lost production every year, and of major industrial incidents.
Developing good alarm management practices is not a discrete activity, but more of a continuous process (i.e., it is more of a journey than a destination).
The sensors relayed their information to the control instruments via analogue signals, such as a 4-20 mA current loop in the form of twisted pair wiring.
At first these systems merely yielded information, and a well-trained operator was required to make adjustments either by changing flow rates, or altering energy inputs to keep the process within its designed limits.
So instrumentation indicating operating units with the plant was grouped together for recognition sake and ease of problem solution.
It was a simple matter to look at the entire panel board, and discern whether any section of the plant was running poorly.
To do this they employed behavioural psychology practices which revealed how much information a human being could collect in a quick glance.
In essence, they were limited by the amount of available board space, and the cost of running wiring, and hooking up an annunciator (horn), indicator (light) and switches to flip to acknowledge, and clear a resolved alarm.
Also, global competition pushed manufacturing operations to increase production while using less energy, and producing less waste.
Panel boards were no longer required, because all of the information that once came across analogue instruments could be digitised, stuffed into a computer and manipulated to achieve the same control actions once performed with amplifiers and potentiometers.
[2] One other unfortunate part of the digital revolution was that what once covered several square yards of panel space, now had to be fit into a 17-inch computer monitor.
The ASM Consortium developed a research proposal and was granted funding from the National Institute of Standards and Technology (NIST) in 1994.
The focus of this work was addressing the complex human-system interaction and factors that influence successful performance for process operators.
[3] The ASM consortium also participated in development of an alarm management guideline published by the Engineering Equipment & Materials Users' Association (EEMUA) in the UK.
Several companies also offer software packages to assist users in dealing with alarm management issues.
The ultimate objective is to prevent, or at least minimise, physical and economic loss through operator intervention in response to the condition that was alarmed.
When a major piece of process equipment like a charge pump, compressor, or fired heater shuts down, many alarms become unnecessary.
This is often the case because the static alarm conditions conflict with the required operating criteria for start-up and shutdown.
To ensure a continuous production, a seamless service, a perfect quality at any time of day or night, there must be an organisation which implies several teams of people handling, one after the other, the occurring events.
To avoid having a full-time person to monitor a single process or a level, information and / or events transmission is mandatory.
In the above case for instance, it can be argued that the low flow alarm does add value as it confirms to the operator that the pump has indeed stopped.
Numerous disasters such as Three Mile Island, Chernobyl accident and the Deepwater Horizon have established a clear need for alarm management.
The methods for making them work properly are documented, and can be applied with minimum effort and maximum performance improvement.