SCADA/HMI Color coding standards (any?)


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Does anybody know about any standard (IEC, IEEE...) for color coding of measurements status (e.g. red=Open/Closed Valve, Red=High-High Alarm...) and fluids (e.g.: yellow=oil) in SCADA/HMI applications?

I have searched all through some standards/guides and I have found no guidance about this...

Thanks a lot.

Bruce Durdle

In the petrochem industry there is a standard colour coding system for real pipes - e.g. mustard brown for natural gas - and it would make sense to follow this for fluid lines on HMIs if the target plant is using it.

Be careful with red/green for status - there is one convention where red is any abnormality, green is normal, and another (mainly used by electricians) where red is live and therefore dangerous and green is dead and therefore safe. These are diametrically opposed and each is defended very passionately by their advocates.

The best guidance is to get inside the heads of the people who will be using the HMI system and do what is most in line with their expectations.

EEMUA in the UK have a basic standard on HMIs but there's that not much in detail about colours particularly.

The ASM consortium have more detailed guidance.

Both these are not free.

There are more general resources on the web. Try looking up human factors with engineering. There'll be a lot of info as it's a broad heading but its worth a go.
On a number of new projects I am seeing an increasing number of 'grey-style' graphics on HMI's, whereby everything (pipes, vessels, pumps, valves, etc.) appears grey or white until attention is required. Depending on the severity of the issue the relevant object may change colour to yellow, red or some other pre-defined alarm colour.

Generally the colour standards are as follows; Graphic background = light grey
Vessels and pipework = darker grey
de-energised state of equipment = darkest grey
energised equipment = white
low-leval alarm or info only = pink
medium-level alarm = yellow
critical/high-level alarm = red
equipment oeverride = blue

The main emphasis with this apporach is to keep the amount of colour to a minimum as you only want problems to draw your attention, as a result of this the pipe colouring, vessel content colouring and other dynamic notifications will generally be grey so as not to stand out too much.

Hope this helps.


SP 101 of ISA is currently working on HMI standards. I am on that committee (but have not been able to participate the last few months due to project deadlines) but we are just getting into being bogged down by such topics.

Nothing initiates a long debate like green or red : )