Ultrasonic water meters achieve second extension

Extended from 9 to 12 service years - this means that the cost-benefit calculation for the investment in ultrasonic water meters has already paid off for Stephan Hahn, operations manager at the Florenberg waterworks association. The Florenberg waterworks association has been using Kamstrup ultrasonic water meters since 2012, and currently has 5,082 active meters. This year, 2021, the second sample renewal of Kamstrup water meters became due. This means that the first generation of water meters can be extended for another three years.

In March 2021, sample testing was registered with a batch size of 2,243 MULTICAL® 21 meters. Under the process, 80 + 16 meters were selected by the test centre of swa Netze GmbH following a lottery procedure. Depending on the batch size, a certain number of meters is required for the random sample; for a batch size of 1,201 to 3,200 meters, that means 80 test items, with a further 16 in reserve, e.g. in case a selected meter cannot be accessed. It is worth knowing that sample testing can take up to 28 days, i.e. the water supplier has three weeks before the test date to remove the selected meters and send them to the test centre.

A successful sampling test allows water utilities to keep electronic water meters installed before 01.01.2019 in the network for a further three years and meters installed from 01.01.2019 onwards for a further two years in accordance with the new calibration regulations.

Only electronic water meters can remain in use for a further 3 and even 6 years if they have passed the qualification procedure required for this. In order to successfully pass the sample testing, a maximum of three meters were permitted to exceed the error values. “As expected, all meters passed the sample test for the second time after nine years of use,” comments Hahn on the successful sample test. “The inspection went extremely well this time too, all the meters passed smoothly,” confirms Michael Kyrrmayr, Head of Testing and Maintenance at swa Netze GmbH.

Strict criteria for the MULTICAL® 21

For Kyrrmayr, this is the first extension to 12 years for electronic water meters. All meters checked complied with the error limits. For a comparison of which error limits MULTICAL® 21 Q3 = 2.5 has to comply with (check at 40 l/h with +/- 3.3% and at 25 l/h with +/ 8.2% error limit), the head of testing and maintenance points out that an impeller meter usually has a flow of 50 to 250 l/h and therefore the checked Q1 flow is higher than the checked Q2 flow of MULTICAL® 21.

“The amazing thing is that with these strict criteria of the ultrasonic water meter, there are zero problems during the test,” says Kyrrmayr. In total, he has already carried out more than 20 sample tests of ultrasonic water meters throughout Germany, all of which have gone well.

Advantages of the static meter

From experience, experts know that not all mechanical versions will pass the test. “With mechanical meters, the sampling procedure is still a lottery, a 50:50 chance of them passing,” says Kyrrmayr, speaking from experience.

Every water network has the challenge of deposits forming in the pipes and becoming loosened over time by flushing. With impeller meters, the very fine overflow channel is affected, resulting in a parallel shift of the error curve and the water does not pass by but goes directly through the register, which leads to a strong positive deviation (i.e. the meter measures more).

With a piston meter, on the other hand, the mechanics are subjected to increased stress, which over time triggers a negative deviation (i.e. the meter measures less) and possibly later a standstill. In addition, every mechanical meter has wear parts (bearings, roller counters, gears, etc.), which is why the devices often do not measure correctly after prolonged periods of use.

The ultrasonic meter has the advantage that no deposits can form and there is no mechanical wear. As a result, these meters have a higher chance of passing the sampling process than mechanical ones, says Kyrrmayr.

Sights set on costs and benefits

Hahn's calculation to keep the Kamstrup water meters in the network for at least two calibration periods worked out. He estimates the installation and removal costs for the sample test at around 40 EUR per meter, i.e. it makes a considerable difference whether all 2,243 meters are removed or only 80 + 16 for the sampling. By extending the calibration period for the second time, the Florenberg waterworks association has generated an annual savings potential of about 30,000 Euros and, in the process, considerably reduced administrative expenses. Kyrrmayr also gives consideration to the amount of installation costs, which is why for him the costs for static water meters pay for themselves after the first sample.

“By having the meters in the network for more than 10 years, everything is economical,” argues the operations manager. It is not only the utility that benefits from the sample testing. The majority of consumers (except for the selected random samples) save a day's holiday to allow the utility access to the water meter.

And it is not only the monetary aspect that is decisive for Hahn, but also the economic and ecological approach, especially with regard to resources. It is worth mentioning not only the material of the meter, which is in use for a longer period of time, but also a reduced administrative effort, less fuel consumption and much more. “Anyone who manages sustainably also needs to keep these things in mind,” says Hahn.

The trend towards static meters

More and more utilities are gradually converting to ultrasonic meters because they recognise the potential of using the sampling method to extend the calibration period, save resources, and act ecologically and sustainably.

Kyrrmayr clearly recognises a trend towards static meters in the water world. On the one hand, he outlines the advantages of the static water meter in the sampling process. On the other hand, he admits the possibilities of integrating gas and water meters in the course of the smart meter rollout, which makes it easier with the electronic version. “In a few years, the mechanical water meter will be history,” Kyrrmayr is convinced.

• Ultrasonic water meters in use since 2012
• Currently 5,082 active meters
• 2018 first successful sample renewal: Period of use extended to 9 years
• 2021 second successful sample renewal: Period of use extended to 12 years