The impact of excessive water pressure on total domestic water consumption

Summary

The pattern of total domestic water consumption and water losses in residential buildings is presented. The main factors that influence the pattern formation are considered. It is taken into account that water consumption is formed not only as beneficial water use that reflects the actual water demand, but also as water losses including water wastage, nonproductive losses through valves and water leakages. It is shown that beneficial water consumption is associated with natural and physiological aspects; water wastage is determined by socio-economic conditions; nonproductive water losses are mostly formed under the impact of technical factors; whereas water leakages – under the impact of time factor. The relationships obtained during field tests between water flow rate and pressure are presented that take into account water consumption increase because of leakages and nonproductive use in residential sector. On the basis of the relationships the calculated nonproductive water rates and leakages in residential sector caused by excessive pressures at different water consumption patterns and diurnal average are cited as an example. It was stated that the highest nonproductive water use was observed at the maximum water consumption, the lowest nonproductive water use was observed at night (in percentage ratio); whereas in case with water losses – vice versa. The average daily water losses in a building calculated with account of water losses caused by excessive pressures at every floor were up to 40%. Considering the relationship between water flow rates in the distribution network and excessive pressures provides for approximating the estimated hydraulic pressure head in the distribution network to the actual values and improving the efficiency of the optimization measures.

Key words

water saving , excessive head , water leaks , beneficial water use , water wastage and nonproductive water use

Optimization of Operation of a City Water Supply System

Summary

Methods of the optimization of operation of a municipal water supply network of the city of Novosibirsk are presented. A number of variants of installation of reducing valves on different sites of the water supply network at the neighbourhoods Pashino (to itself) and Severny (after itself) of the Kalininsky District of the city are considered in detail. The results of the operation of various pressure regulators and frequency converters used at water supply pumping stations during the last few years are given. As a result of the installation of pressure regulators on sections of the water supply network of the Pashino and Severny neighbourhoods of Novosibirsk the total pumping capacity of stations Drinking Centre and Heat-and-Power Station-4 (HPS-4) has been cut by 10–15% and the pressure at the fourth-stage pumping station (HPS-4) has been reduced by 10 m H₂O. At the same time the breakdown rate of the water supply networks of the neighbourhoods has dropped by 10–20%.

Key words

water supply network , pumping station , pressure regulator , frequency converter , excessive head , breakdown rate

Technical and economic aspects of using variable-speed drive in pump units

Summary

The introduction of variable-speed drives is considered as an integral part of the program of reducing pump unit power consumption. Power conservation can be provided both by eliminating pressure excess and by increasing average pump efficiency that can be achieved primarily by pump selection depending on the water and wastewater network operation mode. Pump efficiency depends significantly on the number of operating pumps with variable-speed drives as well as on the algorithms of their interaction with non-controlled pumps. The examples of calculating energy saving and investments for two pump units are presented. The decision on the volume of investments in variable-speed drive retrofit and pump unit upgrade shall be taken on the basis of a business project.

Key words

adjustable electric drive , water supply , pump , power consumption , water disposal , excessive head , power saving