Feature sponsored by Flow, level & control Selecting for flow control, for example,
specifies a valve with an extremely wide range, making it suitable for almost any purpose. In the case of a water application and a 1 inch / 25mm line, the specified device can operate effectively from a minimum flow of 900 litres per hour (l/h) up to as much as 16,070 l/h. Alternatively, to ensure compatibility of specified valves for temperature control and pressure control applications, the sizing tool provides minimum and maximum ratings for these attributes, as well as the Kv value.
CONTROL ACCURACY Sizing components on an individually tailored basis achieves the highest performance. However, for the vast majority of applications, using the Valve Sizing Calculator will not only prove much faster and easier to specify a replacement control valve, but the performance difference would be negligible compared to tailored calculation. Taking the case of flow control, 20 years ago, control valve technology demanded that the accurate valve range was between 60 and 80 per cent open. While these values still serve as a guide, valve accuracy has improved to the extent that individual sizing is no longer required in most cases. Bürkert’s pneumatic valves are accurate to within 0.5 per cent across nearly the entire range of motion, and if required, electromotive valves are accurate to within 0.1 per cent. Providing that the pressure drop across the
valve is an absolute maximum of 50 per cent of the incoming pressure, and that the temperature and pressure do not exceed or fall below the given values, the control valves specified by the Simple Sizing Tool will fit the requirements. Ultimately, this approach covers nearly all applications, except for those with extreme limits and fluctuations, such as steam control in a power station, where a tailored specification would be needed.
COMPLETE CONTROL VALVE SPECIFICATION
For ease of procurement across the system, the Valve Sizing Calculator also specifies control technology type, ranging from angle seat valves for standard liquid flow control, to globe control for pressure modulation. Valve seal design materials are also specified, such as EPDM for aggressive liquids. For hygienic applications, PTFE seals are provided, as well as crevice-free valve clamp ends instead of threaded variants. Control valve specification does not have to be challenging. Using the basic steps provided by the Valve Sizing Calculator, it is fast and simple to confidently specify a control valve that ensures not only the right fit and performance but includes all the components required for a fast and straightforward replacement. Try the Valve Sizing Calculator here:
www.burkert.co.uk/en/more-about/Valve- configuration-and-valve-sizing-of-process-valves
Bürkert Fluid Control Systems
www.burkert.co.uk
Instrumentation Monthly October 2022 17
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