Electronic meters step into the spotlight
The quest to reduce leakage and cut energy used in pumping water has put flowmetering squarely in the spotlight. ABB's Tony Hoyle puts forward the argument for electronic flowmeters over the use of the more traditional mechanical variant.
These options offer significant potential cost savings that can add to the bottom line, while helping to meet leakage reduction targets and improve network information.
Flowmetering in the water industry has been characterised by the use of traditional mechanical meters.
Simple to operate and with a low price tag, these meters have long been seen as
an attractive flowmetering option.
But there are a number of things to remember about this type of equipment, all of which can lead to additional costs further on down the line. Firstly, it will only ever be truly accurate on the first day of installation.
After that time, the meter's accuracy will steadily deteriorate due to the inevitable wearing of the mechanical components.
While a loss of accuracy of a few percentage points may not appear that significant, the potential loss of revenue that this under-registration represents is becoming of increasing interest as water companies look for ways to achieve more precise flow measurement and improve their profitability and levels of service.
The second thing to bear in mind is the meter's total cost of ownership. This includes not just the cost of maintaining the meter, with its associated disruption as the meter is removed from the line, but also the cost of sending someone to manually collect information from several meters at a time.
The pressure being applied on water companies by Ofwat to more accurately identify and address leakages throughout their supply networks, has already led some water companies to employ new technologies to provide more accurate monitoring.
These feature additional capabilities, such as remote GSM-SMS communication, which enable leaks and other problems to be immediately traced and rectified.
Electronic flowmeters that work on the magnetic, ultrasonic and other principles and incorporate electrical, rather than mechanical sensing equipment, have been around in various guises for some time.
Yet with the exception of the MagMeter, they have generally been slow to be adopted by the water industry due mainly to a comparatively higher purchase cost than mechanical metering equipment.
But in most cases, payback on the installation of an electronic flowmeter could actually be achieved in a matter of days, as demonstrated by the following example.
Let us assume that we have a mechanical 6" flowmeter that is accurate to within ±2%.
This flowmeter is installed in a line with an average flow rate of 25l/s, which equates to an annual usage of 788,400m3.
Assuming a cost just for water at £1/m3, over the course of one year, the inaccuracy of the meter would be losing the operator around £13,797 of revenue.
Now let us assume that we replace this meter with an ABB AquaMaster electromagnetic meter, which has an accuracy of ±0.5%. Based on the above flow conditions and water cost, the meter will pay for itself within just 23 days.
Nor is this the only area where an electronic meter can achieve savings.
There are no mechanical moving parts that can be subjected to wear and that will need to be replaced.
This not only ensures that the meter's accuracy is constant throughout its service life, but eliminates the cost, time and disruption associated with removing the meter from the line for maintenance.
Developments in remote communications technology also mean it is now no longer necessary for staff to be deployed to read meters or check on their status.
The company's AquaMaster flowmeter, for example, incorporates GSM-SMS communications technology, providing operators with instant access to real-time data and also historical flow data logged by the meter.
This technology has also made it possible to include a dial-out alarm that warns the operators whenever a problem occurs.
Using in-situ equipment such as ABB's CalMaster 2 verification tool, flowmeters buried underground or installed in underground chambers can now also be verified and tested from the surface, enabling easy and cost-effective performance checks without interrupting the continuity of water supply.
This equipment can also be used to provide a diagnostic health check on the entire flowmeter system together with an early warning of any deterioration likely to lead to system failure.
Despite the cost benefits that electronic meters can bring, the water market in particular is still primarily dominated by their mechanical counterparts and will probably continue to be so for many years to come.
What is becoming obvious, is the shift in emphasis among operators towards understanding the idea of cost of ownership, which takes into account all the costs incurred throughout the life of a flowmeter instead of just its purchase price.
One reason for this is the growing trend toward companies outsourcing responsibility for both supplying and running equipment to contractors, which must ensure they opt for the solutions offering best value for money over the long term. Added to this is the capability of modern electronic flowmetering equipment to integrate with other equipment to provide operators with a wealth of information that was previously unavailable.
When used with equipment such as data recorders and water quality monitoring devices such as turbidity monitors, flowmeters can be used to collect data that can be employed for uses such as improving water quality.
To summarise - the water market is likely to see a steady rise in demand elec-
tronic flowmetering, as users increasingly become aware of the benefits that these flowmeters can bring to the bottom line, in terms of reduced cost of ownership and the ability to identify areas where revenue is currently being lost. With in-situ verification, disputes over flowmeter measurements can be easily resolved without having to remove the flowmeter from line to be tested on factory calibration rigs.
Tony Hoyle is UK flow product manager at ABB. W: www.abb.com