Is the need for local plant indication a thing of the past?
16 September 2009
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 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 plant display specialist possibly survive?
Beka developed the first 4/20mA loop-powered I.S indicator in the early seventies and has kept apace with market trends, recently launching a range of fieldbus indicators and displays.
But, another threat comes via displays mounted within field transmitters – a viable solution if a calibration aid is required instead of a large, easily accessible, designed-for-purpose display. However, unlike a transmitter, our units can be located exactly where the operator needs them and are not subject to design or positional constraints imposed via another primary function.
Additionally, the range of accessories offered by Beka can finesse innovative process solutions that in turn can save money and increase overall plant availability. Alarms and flashing displays bring obvious benefits whilst backlights confer the option of locating the display almost anywhere – a flexibility that is enhanced by the robust and durable housings that we supply as standard.
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 suggests the adoption of a fallback position in case others fail and 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 in any event many operations such as tanker loading, manual valve interventions and inventory checks remain dependent on a human interface to some degree and therefore remain popular areas for display adoption.
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