Energy conservation starts with reliable measurements
14 September 2012
Energy efficiency has become an increasingly important focus for industry in recent years, as engineers seek reductions in the power demands of process equipment through better use of higher level control systems.
But don’t ignore those basic measurements – particularly flow measurements - which are the very foundation of a successful energy conservation campaign says Mike Powers.
Concentrating on the operation of higher level control systems is important, but it risks neglecting some of the fundamental components that must be properly specified and operated if these systems are to provide long term energy consumption reductions. Mechanical and electronic flow sensors and switches may be simple devices but if they do not provide reasonably accurate, reliable and consistent performance, then higher level systems will not deliver.
By ignoring the function of basic components engineers risk energy efficiency programmes missing their targets. Fortunately, advances in the design and construction of flow sensors have given manufacturers greater faith in the performance of these devices, and the confidence to apply their measurement data to the optimisation of industrial operations. Compact size, durability and low cost are features of a new generation of flow sensors that are ideal for a variety of duties in many industrial applications.
But with the huge range of flow measurement options available, comes the difficulty of selecting the product most suited to the application. For example, will it have to contend with high temperatures; is the response time critical? What challenges do the measured media pose?
Robust, solid-state flow switches manufactured from stainless steel are available for use with both conductive and non-conductive fluids, fluids of variable viscosity, as well as slurries and fluids with large entrained particulates. Meeting a variety of pipe sizes for flow rates from 0.45 to 45 litre/min, these switches can be mounted in any orientation and offer an alternative to traditional flow switches with moving parts that may be susceptible to premature wear, jamming or even breakage.
Set point switching or flow rate?
Devices are also available for both set point switching and/or flow rate measurement. An example is RotorFlow, a series of products from the author’s company, which provides both these options. This is a paddlewheel device that offers a visual indication of flow. It delivers a pulsed dc output of between 4.5 and 24V (proportional to flow rate), or an adjustable 1A switched output, compatible with most digital rate meters, totalisers, and other electronic controllers. Flow rates ranging from 0.4 to 227 litre/min are covered, and the devices offer accuracy to within ±7% of range.
Mike Powers is with Gems Sensors and Controls
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