HOW TO REDUCE THE QUANTITY OF WATER LOSSES
The main components of water utility losses are:
- technological costs;
- pipeline breaks;
- unauthorized selection;
- lack of quality measurement.
The last three components are direct losses of Vodokanals. But the most important component of all losses is the lack of qualitative measurement, primarily in the housing stock - the main consumer of water. Why, precisely the lack of a qualitative measurement, is classified as the main loss, and not pipeline ruptures, as is commonly believed? If we conditionally accept that the main losses lie in impulses, each settlement would have to turn into a kind of Venice.
To understand where to look for losses in the housing stock, consider the example of an apartment building, fully equipped with apartment water meters and having a common device. According to statistics, in a residential building there is always a difference (imbalance) between the readings of the general water meter and the total readings of the apartment meters, which is 25-45%. If the calculation of subscribers for the consumed water according to the readings of apartment meters takes place directly with the water utility, then the imbalance is the water utility's losses.
1. Leaks in plumbing fixtures.
In everyday life, there are expenses below the sensitivity threshold of a conventional apartment water meter, especially when installed in a vertical position. These are toilet tank leaks, faucet leaks, etc., which are summed up throughout the house and reach the consumption recorded by the common house water meter.
2. Installation of apartment meters in a vertical or inclined position.
More than half of residential water meters are installed in a vertical or inclined position. The sensitivity of meters when installed in an inclined position is as low as when installed vertically. Let's see how this affects the measurement accuracy.
When the meter is operated in an inclined or vertical position, the contact area of the impeller axes with the bearings increases, which means that friction increases. As a result, the sensitivity of the meter is lost at low flow rates, i.e., the measurement accuracy is lost.
3. Metrological accuracy class of water meters used
All apartment meters of the mechanical principle of operation have two flow ranges - lower and upper. The boundary of the transition from the lower range of costs to the upper one is called the transitional flow rate and is denoted by Qt.
The relative measurement error in the lower range of flow rates, from the minimum flow rate Qmin to Qt is ±5%, and in the upper range from Qt to the maximum flow rate Qmax ±2%. Therefore, the smaller Qt, the wider the zone with an error of ±2%. In turn, the lower range with an error of ±5% becomes narrower, and the minimum flow rate and sensitivity threshold are shifted to the beginning of the measurement (zero flow rate). This means that the wider the measurement area with an error of ±2% (blue) and the smaller the dead (white) area, the higher the measurement accuracy.
As can be seen from the diagram, the highest measurement accuracy is provided by water meters in the metrological accuracy class "C".
The two bottom lines of the diagram correspond to the flow ranges above the metrological accuracy class "C" and correspond to the types of meters "820" and "620" produced by the Sensus group. At the same time, it should be noted that these water meters do not deteriorate their metrological characteristics when installed in a vertical and inclined position.
4. Stability of metrological parameters.
The stability of the counter depends on:
- device design;
- quality of production of components;
- the ability of the materials used to resist the deposition of hardness salts, the so-called "scale".
The duration of stable operation of the meter is characterized by the calibration interval. The higher the value of the calibration interval, the more stable the metrological characteristics declared by the manufacturer, and hence the measurement accuracy.
5. Protection of the water meter from deliberate interference.
An important factor affecting the balance of water consumption in the house is the security of the apartment water meter from deliberate interference with its operation.
There are many ways to influence the operation of the counter. The most popular of them is the effect of a magnet. There is a type of meters that do not have a magnetic coupling in their design - these are wet or semi-moist. Such counters are 100% anti-magnets.
It is necessary to pay special attention to the relevance of this issue. Currently, many markets sell apartment meters complete with a set of magnets. No anti-magnetic protection can withstand modern magnets.
The way out is the use of apartment water meters of the "wet" or "semi-moist" type, for example, the "820" type meter manufactured by Sensus.
6. The duration of the process of collecting readings from water meters.
The balance of water consumption in the house is greatly influenced by the duration of the process of collecting readings from apartment water meters, as well as the objectivity of the data obtained.
Currently, data collection takes place over the course of a month. In the process of visual information removal, intentional and unintentional distortion of readings can occur.
The introduction of systems for remote collection and transmission of information will provide up-to-date and objective data in a short period of time, eliminate the human factor and significantly improve the quality of accounting.
So, in order to minimize the losses caused by underestimation, it is necessary to improve the quality of measurement. And the quality of the measurement directly depends on the characteristics of the water meters used. All the necessary characteristics that ensure high-quality measurement are met by the counter type "820" produced by the Sensus group.
The availability of high-quality measurement and the introduction of remote data collection systems makes it possible to obtain excellent results, the relevance of which is not lost over time, to reduce the balance of water consumption in an apartment building to almost zero.
So, for example, in the city of Ternopil in a residential building after the replacement of meters with type "820" and the introduction of the remote data collection system Sensus Scout (this project was described by us earlier), for 19 months the imbalance is less than 1%, while before the replacement of the meters, the losses were 19.5%. The stability of the balance indicator over a fairly long period of time confirms the reliability and stability of the metrological characteristics of water meters, and also guarantees a quick return on investment.
In the city of Tetiev, Kyiv region, before the replacement of all apartment meters in a residential apartment building, the balance was -54% (losses), after replacing with the type "820" with a radio module for remote data transmission, the balance of water consumption for 10 months is +1%.
The use of high-precision meters and the introduction of a remote data collection system will make it possible to increase the implementation due to the fact that the losses caused by underestimation will be transferred to the category of accounted. The payback period of equipment depends on a number of factors. The calculation of economic efficiency is given below.
Methodology for calculating the economic effect from the introduction of type 820 meters and the Sensus Scout radio system.
In order to understand what the total cost of the project is, it is necessary to know the number of objects (residential apartment buildings) and the number of subscribers who participate in the project.
The amount of investment invested in an object (house) is calculated by multiplying the required number of meters installed at the object by the cost of a water meter with a radio module, to which a share of the cost of the terminal is added. The Psion terminal is a device for reading information from radio modules and programming them. Since only one terminal is needed, its cost is divided in equal shares for each potential object (house) participating in the project.
And in order to understand how cost-effective the introduction of high-precision meters and the Sensus Scout data collection system will be, it is necessary to calculate the losses caused by the underestimation of water consumption at the facility (house). Thus, the average underestimated volume of water at an object (house) for one month is determined based on the statistical data for the object (house) as the difference between the readings of a group (common house) meter and the total readings of subscriber (apartment) water meters. Multiplying this indicator by the tariff (water and sanitation) in a given settlement or for a given facility, we get the cost of monthly water losses.
The ratio of the amount of investment to the cost of monthly water losses caused by the underestimation of its consumption will show how long the investment will pay off.
For example, in Tetiiv, where 10 houses are involved in the project, the payback period for investments was 26 months (2 years and 2 months).
The IN-PREM enterprise offers time-tested European solutions in the field of water measurement and accounting, tested by the specifics of Ukrainian operating conditions, which allow water utilities to minimize losses.
Lukash Oleg
Krasnozhon Iryna