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UDC 628.311

Yegorov N. L., Loitzker Oskar

The effect of shortening the feed section of Venturi flume on the error of measuring the liquid flow rate

Summary

The use of flow meters with Venturi flumes for measuring the flow rate of effluent before discharge into the water reservoir or of wastewater transported to the treatment facilities is reported. The new construction projects boost the flow of wastewater; the level of the upstream water rises, the relative length of the feed section expressed in upstream maximum depth units decreases and does not meet the regulatory requirements any longer. When the similar situation occurs in the throat of the pressure flumes the flow meters are admitted to service however with a higher effluent coefficient error. The procedure of estimating a complementary error at the reduction of the relative feed section length in case of measuring the liquid flow rate with Venturi flumes is suggested.

Key words

measurement error , wastewater , flow rate measurement , Venturi flume , throat

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UDC 628.311

Choosing the method of gravity flow measurement in public sewers

Summary

The aspects of choosing the method of measuring the flow rate and volume of wastewater gravity flow, particularly in case when the measurement results are used in accounting procedures (commercial accounting) are considered. It is shown that before studying the methods of measurement possible replacing gravity flow with pressure flow shall be considered because pressure flow rate can be measured more accurately. This measurement option is optimal from the technical point of view; however, in case the pressure section in the gravity pipeline is not available additional expenses are required for the water main reconstruction. In case this option is unacceptable the following methods of gravity flow measurement shall be considered (in the order of application priority): «level-flow rate» with the use of standard orifices (weirs and flumes) according to MI 2406-97 regulatory document; «level-flow rate» without any orifices with preliminary calibration of the measuring section according to MI 2220-13; «velocity-surface area» with the use of ultrasound flow meters; studying the velocity profile of the cross-section of the water main; calculation-instrumental (balance). By the specific example of an ultrasound flow meter it is shown that the flow rate error subscribed by the technical documentation can be several times lower than the actual one.

Key words

flow rate , measurement error , wastewater , ultrasonic flowmeter , gravity flow , flow measuring flume , calibration of measuring section

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UDC 628.1.033:351.777

Samburski Georgi, Plitman S. I., Pestov S. M., Tulakin A. V., Ampleeva G. P.

On some problems in water treatment related to the implementation  of «On water supply and wastewater disposal» Act

Summary

A number of problems of regulating the process of drinking water purification for public water supply systems related to the water quality meeting the established hygienic requirements and performance targets are considered. It is shown that water and wastewater providers using the methods of risk assessment can optimize the measures aimed at improving the quality of drinking water in the context of choosing the implementation dates and priorities. It is noted that measuring water quality parameters without any consi­deration for procedural and sampling errors may not reflect actual concentrations of pollutants in drinking water in public water supply systems; whereas five-fold exceeding maximum permissible concentrations is possible which cont­ravenes both drinking water hygienic standards and criteria of significant drinking water quality deterioration.

Ключевые слова

potable water , water supply , water treatment , water quality , measurement error , health risk

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UDC 628.17.08:681.121

Lurie M. S., Lurie O. M.

Assessment of a Random Error of Vortex Flow Meters in the Course of Their Operation

Summary

Methods of the assessment of a random error of vortex flow meters and water meters in the course of their operation are considered. This methodology is based on the statistical treatment of measurements of instantaneous values of vortex formation of the flow meter placed in the working pipeline. The scheme of connection of the vortex flow meter implemented in the submerged variant reducing the cost considerably and making it possible to use these instruments for measurement of a flow rate in large diameter pipelines and open canals is presented.

Key words

water meter , flow meter , pipeline , measurement error , methods of error assessment