The Problem!!!!!
The water meters do not measure low flows. Leakage in the house or even open taps with flows lower than the measuring threshold can’t be detected by the water meter and therefore there is a lost revenue to the water company. From 5% to 10% of the total water consumption is lost due to low, unmeasured flows.

The solution!
Unmeasured-Flow Reducer (UFR)

What does the UFR actually do?
The UFR works by changing the way that the water flows through the water meter at low flow rates. Normally there is not enough energy in the flow to activate the water meter register at low flow rates. With a UFR installed the same flow is divided into measurable quantities of water that pass through the water meter at certain intervals, these quantities of water have enough energy to activate the water meter register and hence the flow is finally measured. With a UFR installed, the water meter operates in cycles at low flow rates, where the water meter flow-indicator (leak detector) is stationary most of the time and then rotates at regular intervals. At higher flow rates (where the water meter operates satisfactory without the aid of the UFR), the UFR detects the higher flow rate and automatically goes into the override mode (i.e. the water meter measures flow as though the UFR was not installed in the water system). In the override mode the UFR (as in the low flow rate mode) also acts as a non-return valve, i.e. it closes when the downstream pressure exceeds the upstream pressure.

How does the UFR work?
The UFR is a differential non-return valve, designed in such a way that the pressure difference required to open it is more than that required to keep it open. The pressure difference to open the UFR is 0.4 bar, whilst the pressure difference to keep it open is 0.1 bar.
When a leak develops the downstream pressure drops.

When the downstream pressure drops below 0.4 bar of that of the upstream pressure, the UFR opens and allows for a flow rate above that of the measurement threshold.

The free flow of water through the UFR equalizes the pressure across the UFR and allows it to close. The continuing leak downstream to the UFR will make this operation repeat itself over and over again. Every time the UFR opens, a quantity of water passes through the water meter at a flow rate above the measurement threshold of the water meter and so the flow is measured.

Test case: Installation of UFRs in Ein Karem, Jerusalem
In March 2005, 120 UFRs and 360 UFRs were installed in two separate DMAs in Ein Karem, Jerusalem. The water meters in these DMAs are multi jet, Qn 2.5 class B.

The under registration percentage was recorded prior to and after the installation of the UFRs and is a comparison of the sum of the domestic water meter readings to that of the main water meter of the DMA. The table below summarizes the results.

Location	No. of Consumers	With or Without UFR	Period of Time [months]	Under- Registration [percent]
Ein Karem First DMA	120	Without UFR	8	16%
		With UFR	6	6.1%
		Contribution of UFR		9.9%
Ein Karem Second DMA	360	Without UFR	8	26%
		With UFR	6	18.8%
		Contribution of UFR		7.2%
		Average Contribution of UFR		8.50%

With respect to revenue calculations, it is very important to take into consideration the following: Per liter, the reduction of apparent losses, after the water meter, is more cost effective than the reduction of real losses before the water meter.

The reasons for this are:

• The loss of revenue due to one litre of water being unregistered by the water meter is substantially higher than the cost of supplying that same litre of water into the system.

• If water is billed according to a tier system, then the loss in revenue due to water meter under-registration will be according to the highest tier billed.

Conclusions:
Leakages and other unmeasured water flows at low flow rates were found in many of the households tested. The UFR succeeded in the reduction of unmeasured flow and was found very effective in reducing apparent losses in Ein Karem, Jerusalem. The contribution of the UFR to the flow registration of the water meter was very significant (8.5%). In response to this study, the water company of Jerusalem decided to install UFRs in the city.

 

More information:

Data sheet (630 KB)

View movie

 

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