ABB has now fully integrated manufacturing, development, sales and marketing of the former Torbar Flowmeters Ltd. business and has formally 
nload="javascript:if(>500)=500" align=right border=0>released a range of averaging pitot tubes. These products retain the Torbar name, which is known and respected worldwide, and incorporate all the versions previously marketed by Torbar Flowmeters. In-line, fixed and withdrawable designs are available for pipe sizes from 10 mm to 8 meters in diameter.
Key features of the Torbar range are its sensor design and the use of a "dual averaging" technique. The tube design features unique profiled flats around the downstream hole. These flats define the separation point of the flow lines from the tube and create a stable pressure area at the downstream pressure sensing hole. This design maintains a more constant flow co-efficient at high velocities, giving the Torbar pitot tubes a wide rangeability for measuring flows rates (turndown).
The dual averaging feature takes the pressures developed at each upstream hole (from the impact of the flowing medium) and initially averages them within the outer impact tube. It then averages to a second order (increasing accuracy) within the internal averaging tube. By ensuring that the upstream impact pressure signal is not biased by the pressure at a sensing port next to the output point, the meter is less susceptible to the effects of non-ideal upstream pipe work configurations.
The Torbar units are being manufactured as a one-piece outer tube. This gives the unit optimum strength by avoiding the need for welded joints, which could be points of failure under process stresses. ABB Torbar averaging pitot tubes are available in a wide variety of wetted materials to suit most liquid, gas and steam applications, whether flowing in circular or rectangular pipes or ductwork. For stack gas emission monitoring, an automatic air purging system is availble to keep the sensing ports clear of particulates.
ABB also supplies a comprehensive software package to facilitate Torbar tube sizing, selection and product configuration. Called Torwin, the software enables quick and simple Torbar calculations. In addition, it performs a resonance frequency check - vital for insertion devices - to avoid operation in the critical velocity range where resonance could damage the unit. Torwin also allows the generation of product coding most suited to the application. The calculation/coding data can be exported into several document formats.
ABB is a leader in power and automation technologies that enable utility and industry customers to improve their performance while lowering environmental impact. The ABB Group of companies operates in around 100 countries and employs about 107,000 people.
