For the electro-hydraulic slide valve, is it better to display the percentage on the DCS or the actual opening degree?
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Recently, the catalytic unit was taken out of service for maintenance. While adjusting the electro-hydraulic slide valves, the operators requested that the DCS display the actual opening degree of these valves (i.e., the actual travel distance; previously, the DCS showed the valve position as a percentage). After discussing this with the operators, we changed the display to show the actual valve position for all electro-hydraulic slide valves. However, this has created difficulties for our future maintenance and troubleshooting tasks. If components such as valve stems or valve plates are replaced, the travel distance may change, and it is still necessary to ensure that the actual opening degree at the site corresponds to the range indicated by the DCS, otherwise there will be display errors. Dear sea friends, please share your opinions and views.
This post was last edited by yuexf01 on 2012-6-12 08:03. I think showing percentages is more straightforward; it can be understood regardless of whether one knows the internal structure of the valve or not. Why do operators need to display the actual travel distance?
The instruments here all display percentages, as required by the manufacturing process
First of all, it’s important to clarify one thing: no factory should allow operators to decide whatever changes need to be made. Even if changes are necessary, there must be established procedures and processes for carrying them out, such as getting approval from the leaders of the relevant departments or company executives. Things cannot be handled haphazardly. Second is the issue of percentages and stroke lengths – percentages represent the degree of opening of the valve, while stroke length refers to the distance it moves. If they don’t even have this basic knowledge, they aren’t fit to be operators at all, and there’s no need to explain anything to them. Stick to the fundamental principles and don’t let operators dictate your actions!
I have a foolish question. . . Aren’t the percentage and the actual opening the same?
I think percentage and opening degree mean the same thing. But what the original poster is referring to is the actual distance of the journey. There are instructions on the 1st floor. .
Under normal circumstances, what operators need to know are the process operation parameters; the specific position or travel distance to which a valve should be opened is not something that concerns them, unless special operating conditions require knowledge of that travel distance. Besides, they have always used percentages for such purposes – so why change that? It’s just a matter of sticking to what’s familiar!
Mm-hmm. The projects we worked on before also displayed percentages, which we also referred to as opening degree. As for the itinerary, I think it is something that professionals or designers need to refer to
It’s different; the opening degree of each valve varies. Some range from 0-10, while others range from 0-12, etc. It’s not expressed as a percentage! Personal opinion
The best approach is to have two types of displays on the DCS, so that everyone can understand it.
First of all, for such issues, it is necessary for the process and design teams to conduct research and make decisions, rather than having the instrumentation technicians handle them. Second, if changes are indeed to be made, there must be strict procedures; otherwise, if problems arise, you will have to bear the consequences. Third, in most cases, it is required that the values be expressed as percentages, so that the process operators can observe the valve opening in person and gradually understand the relationship between the degree of opening and the control parameters. *It will get better with practice. Fourth, if interlocks are in place, modifying the valve opening also requires corresponding adjustments to the interlocks.