Duisburg, February 2, 2009: After 30 years of validity, the definition regarding the accuracy of variable area flowmeters in the VDI/VDE 3513-2 guideline was revised in the August 2008 edition. Instead of the accuracy classes, requiring a formula to calculate the permissible deviation for each measuring point, all that is now required is the simplified indication of the error limit which states the maximum permissible percent of deviation from the current measured value. For example, if the error limit is stated as 1%, that refers to a constant, permissible measuring error of one percent of the current measured value. It is only for the beginning of the measuring range that additional error influences, depending on the design, will be taken into special consideration.
This translates into considerable change for the manufacturers applying this guideline: From determining and verifying the new error limits to amending documentation, calibration protocols and procedure instructions right down to user information. In the end, however, the simplified definition meets one of NAMUR's demands as a lobbyist for measurement and automation technology in the chemistry industry.
The guideline reflects the current state of the art. In this regard, manufacturers are well advised to make reference to the guideline in their specifications. KROHNE tackled this task early on and has been supplying devices in accordance with the currently valid version of the VDI/VDE 3513 guideline since 1 November 2008.
Part 1 of the VDI/VDE 3513 guideline deals with calculation, part 2 with accuracy and part 3 with recommendations for installing variable area flowmeters. As one of the first flow measurement principles, the method is still one of the most cost-efficient and sturdy when it comes to measuring liquids and gases. In addition, it needs no auxiliary power. KROHNE is the world market leader for variable area flowmeters and offers a complete range of float technology with glass or metal cones, from measuring extremely small volumes using dosing equipment to process monitoring of DN150 pipelines.
About KROHNE: Established in 1921, KROHNE is a family-owned business employing 2,510 people around the world with representatives on all continents. The company headquarters are based in Duisburg, Germany. KROHNE is a market leader in the development and manufacture of innovative measurement technology and prides itself on exceeding customer expectiations in terms of quality, performance capability, service and design.
GNN VIETNAM
Email : contact@gnnvietnam.com
Website : www.gnnvietnam.com or www.gnn.com.sg