Scottish Water was recently faced with an interesting problem at the Alnwick Water Treatment works in Edinburgh. In a pipe system dating back to the 1880s a failed (and ancient) venturi-type system needed replacement with modern technology. One of the major considerations was potential intrusion damage to existing pipework. Conventional standard flowmeters would require permanent inline location, with civil engineering costs running into many thousands of pounds. Recent estimates from the industry suggest that in most permanent installations typical instrumentation costs are no more than 10% of the total project costs. At Alnwick it was felt that, because of the age of the pipeline concerned, civil engineering costs would be an even bigger factor. Happily, a solution requiring minimal invasion and installation time was provided by Flowline.
Multi-Mag is an insertion electromagnetic flowmeter which is introduced to the pipeline through a 2in valve usually installed using “hot tapping”. This allows the flowmeter unit to be inserted or removed without interruption to the flow. Furthermore the Multi-Mag technology provides accuracy at least comparable to conventional flowmeters. Following excavation down to the pipeline at Alnwick, the new valve and flowmeter were installed to the live main within two hours. The total project, including full commissioning, took less than a day.
Multi-Mag, which is manufactured by Marsh McBirney, is widely used in the UK water industry and has also been specified by Southern Water, South East Water, Northwest Water, Anglia Water and Severn Trent.