| | 
Magnetic flowmeters are one of the oldest methods for electrically measuring water flow, but nevertheless, the instruments are still beingused as they offer reliable operation under a wide range of flow conditions. Modern electronics has reduced their power consumption to suchan extent that some models can be powered for years with batteries.
Thai water authorities
In Bangkok, Thailand water authoritiesthere wanted to reduce the volume of water they deliver that it doesn’t get paid for. This so-called non-revenue water is mainly lost thoughleaks, although theft, metering inaccuracies and authorised unbilledconsumption, for example, by the fire services, all play a role. Theyasked ABB to supply them with flowmeters that would help them trace the leaks.
MWA supplies potable water to customers throughout Bangkok and the surrounding district, which is home to a growing population currently estimated to be around 9 million people.
The desire to trace water leaks led the Metropolitan Water Authority (MWA) to sign a $4.06 million contract with ABB to deliver 390 MagMaster electronic water meters. The project also includes ABB Italy supplying CTU800 -CPE remote terminal units to transmit the flow data from the water meters to ABB’s Water Leakage Management System (WLMS), which allows MWAto access all the information from a central location.
MagMaster meters are suited for this type of district metering application. District metering accurately measures the flow of water into different areas as a way of monitoring patterns of water consumption and checking for leaks. Detailed analyses are made at night, when domestic consumption is at a minimum.
The low flow rates involved would beimpossible to handle for mechanical flowmeters, which typically stallunder low flow conditions. But this is not a problem for the MagMaster, which offers accurate readings over a flow range of 1500:1. In addition, the MagMaster’s IP 68 rating and two-year warranty permits the sensor to be buried. This eliminates the need for meter pits or chambers and so helps to significantly reduce installation costs.
German coal mines
Mining company RWE Power also wants to measure waterflow, but in an area underground that is difficult to access. Battery-powered meters turned out to be the only solution.
The purposeof the water measurement is to help preserve groundwater based marshesand wetlands around its German coal mines. The meters monitor the amount of water being pumped back into the nature reserves from RWE’s open cast lignite mines, where constant pumping is needed to control groundwater levels in three big mines.
RWE was previously using mechanical flowmeters to measure the water pumped back to the marshes. The need for more accurate measurement of water flows and automatic datamonitoring made electronic flowmeters an attractive proposition. However, with many of the meters located beyond the reach of mains electricity, it was difficult for RWE to find a suitable electronic alternative for the sites.
AquaMaster meters from ABB provide the solution. Fitted with their own battery power supply, the flowmeters can beinstalled in locations where no mains supply is available.
Whenever RWE maintenance engineers find that a mechanical meter has failed, they now replace it with an AquaMaster as standard. With a measurement accuracy of ±0.5% over a turndown range of 1000:1, the meters canalso deliver accurate measurement even at extremely low flow rates, compared with their mechanical counterparts which can only offer an accuracy of ±2%.
Another advantage of ABB’s meters is that particles in the untreated mine water led to frequent maintenance as sand inthe water attacked and eroded the mechanical meters, so the company initially tested 11 units in its mines for nine months. The units provedso successful in testing that RWE ordered a further 35 instruments, ranging in size from DN50 to DN300.
| |
