Is the need for local plant indication a thing of the past?



Alec Robshaw, sales director at Beka Associates argues against the removal of local indication suggesting that there's no replacement for the 'old-school practice of walking the plant'.
 

With the now almost de rigueur adoption of centralised control systems (be they DCS or SCADA, Fieldbus or conventional) it would be logical to assume that the use of large local control panels full of Visiwinks, controllers and gauges is becoming truly extinct. And you would most probably be correct, with 'Ex' HMI's filling the gap where demand still remains. Furthermore, the strategic - and indeed now mandatory - objective of risk avoidance suggests that operational staff should, wherever possible, be displaced from working within hazardous environments, thus further devaluing the benefit of any local plant indication. So how can an established local display specialist such as BEKA possibly survive?

The answer is both simple and diverse.

As a long-established manufacturer it is certainly true that BEKA has thrived whilst other worthy competitors have deserted the field, perhaps leaving us increasingly dominant in the rarefied market of hazardous area plant indication. Increasing legislation and high certification costs have more recently accelerated this process, although perversely we would prefer to see a global standard emerge even if this results in more competition - it would be naïve to believe that truly open markets favour the bottom line. This is why we continue to refine our products in pursuit of the best possible specifications coupled with an efficient control over manufacturing costs, thus keeping our prices competitive.

Secondly, having developed the first 4/20mA loop- powered I.S indicators we have kept apace with market trends and have recently launched a successful range of fieldbus indicators and displays to complement their more traditional analogue brethren. Early entry into these markets have lent us an implicit understanding of their application and such knowledge translates into our design specifications, the benefits of which may not be immediately apparent except to the cognoscenti. Where much bigger and better companies have found themselves casualties of their untofore success we have continued to purposefully adopt a much riskier pioneering role, rather than simply being a market follower. Of equal import, however, is that these more recent innovations have raised our profile amongst an international audience that may have previously neglected or overlooked our erstwhile benefits.

Another threat comes via displays mounted within the field transmitters, which is a perfectly viable solution provided that it is a calibration aid that is needed instead of a large, easily accessible, designed-for-purpose display. Unlike a transmitter, this latter can be located exactly where the operator needs it and is therefore not subject to design or positional constraints imposed via another primary function.

Finally, the wide range of accessories that BEKA can offer can finesse more innovative process solutions, which in turn can save money and also increase overall plant availability.

 

This latter is harvested via their primary benefit - the display of plant variables that in turn can inform a process operator of real-time occurrences. Alarms and flashing displays bring obvious benefits whilst backlights offer the opportunity to locate the display almost anywhere - a flexibility that is enhanced by the robust and durable housings that we supply as standard.

BA324E Loop powered indicator
 

But none of this helps if demand is in decline, I hear you say.

In response, I would argue that it is difficult to justify the removal of local indication on a safety basis, although cost reduction is of course a primary objective. So whilst large local panels may indeed be a thing of the past, the need to easily access critical or dynamic plant information remains essential. Good engineering practice also suggests the adoption of a fallback position in case others fail and even the old-school practice of 'walking the plant' lends a pair of eyes and ears to the process that no end of sensors and transmitters can replace. The benefit gained from the judicious and occasional adoption of local displays is therefore obvious, and even if the MTBF or SIL rating of a loop is considered to be undermined by the insertion of a loop-powered indicator (despite our designs having inbuilt fail-safe continuity) this can be overcome by generating a dedicated 4/20mA output specifically for such a local display. In any event, many operations such as tanker loading, manual valve interventions and tank inventory checks remain dependent on a human interface to some degree and therefore remain popular areas for display adoption.

To conclude, BEKA has successfully embraced the advent of both centralised control philosophies and an increasing migration towards truly digital solutions, and as a result has continued to enjoy strong demand for local displays motivated by various needs. As a result BEKA remain pre-eminent in this market and our continuing innovation in supplying well-engineered, cost effective and reliable display solutions should see us celebrating successful growth well into the coming century.

First publised on http://www.controlengeurope.com, September 2009