Hydraulics & Pneumatics November/December 2022

KNOWLEDGE BASE Process control infrastructures will predominantly use programmable logic controllers (PLCs) as the main hub for instructions, process monitoring and diagnostics. In many cases, these will be connected to human-machine interfaces (HMIs) to enable an easier way to interrogate the PLC without the need for a laptop computer. Decentralised simplicity However, all of this equipment is usually located away from the process itself as part of a decentralised control network. As such, it doesn’t help the plant technician as he makes regular inspections of the process to immediately see any issues with components such as the control valves. What is needed is a 20 HYDRAULICS & PNEUMATICS November/December 2022 www.hpmag.co.uk simple and easily assessed signal or display that highlights any issues locally. Local, at-a-glance diagnostics can take several forms. The most obvious is the use of coloured LEDs that are located in the control heads of each process valve. With normal operation indicated by a green display, it is very easy to spot any out-of-specification operation, which is clearly denoted by amber or red indicators. For a decentralised control architecture, local valve control islands predominantly offer very little in terms of diagnostic information. This is a typical situation where plant operators would need to interrogate the PLC before they could gain any insight into any faults in the system. However, there is an alternative that can improve this situation. Optimising operator performance The use of coloured indicators according to NAMUR NE107 is common practice in process control applications. Bürkert and many other manufacturers have used this standard across many product lines to improve the effectiveness and efficiency of plant operators. However, improving awareness of an issue is just the first step – rectifying the situation quickly is where the most significant savings can be made. For applications that use decentralised control, the pneumatic valve islands provide the local process management, but any diagnostics would need to be Process automation has delivered huge benefits for manufacturers in many industries. In everyday use, plant operators are far from being made redundant, they still need to make regular inspections of the process, among other things, looking for leaks and making sure the control valves remain in good operation condition. These activities are made easier by local diagnostics indicators, which are used on valves and local control distributions. Greg Wainhouse, industry account manager – water, Bürkert, looks at the ways in which manufacturers of process control equipment are making life easier for the plant operators and maintenance technicians. Local process diagnostics