Hydraulic design of measuring weirs with a triangular profile chute

Summary

The method of designing measuring weirs with triangular profile chute is presented. In the regulatory document MI 2406-97 «GSI (State System for Ensuring Uniform Measurement). Liquid flow rate in water and wastewater gravity channels. Measuring methods with the use of standard weirs and flumes» that regulates the use of flow metering devices for measuring water flow rate in gravity water supply systems and sewers the design aspects have been condensed without actual examples. This article aims at filling this gap. The conditions that provide for the possibility in principle to use the method of measuring liquid flow with the use of standard orifices (weirs and flumes) are considered. Such condition, in particular, is the availability of a straight-line channel section of adequate length with free (without backflow) flow. The design procedure is presented with specific reference to flow measuring in a concrete rectangular channel 3.5 meters wide with a maximum flow rate of 56 250 m³/h. The procedure suggests sequential determination of the maximum weir head and chute height as well as verifying the conformity of the weir with a triangular profile chute to the regulatory requirements including possible weir submergence with calculating the maximum flow level in the channel downstream. The ratios between the chute width and maximum head, maximum head limits and Froude number are also verified. Further in the process of designing and basing on the hydraulic calculations the type of the flow-level meter and its metrological performance are chosen and the geometry of the chute is determined.

Key words

flow rate measurement , gravity flow , weir , triangular profile chute , hydraulic design

Tools for developing schemes and electronic models of water and wastewater networks

Summary

RF Government Decree No. 782 «On water and wastewater schemes» together with the applicable Rules specifying a number of provisions of Federal Law «On water supply and wastewater disposal» are considered with relation to the problems that water companies are facing in the process of its implementation. Developing electronic models of water and wastewater systems is a task of the companies that are directly responsible for providing these services. Comparing to electronic models schemes are more general information structures. Models serve as data sources for scheming and allow predicting network development. In the process of data transfer from electronic models to network schemes the use of identical software is sufficient. To solve this problem geographic information systems that are optimal for making an inventory of the network elements are most appropriate. Herewith the software for math modeling shall be able to import the available data. The direct use of the imported model in calculations is possible only if we have relatively small-sized networks. For network model building it is reasonable to use specially configured software which is of prime importance for big cities. When choosing the software special attention shall be paid both to the possibility of communicating with the geographic information system at the data level and to the availability of means to provide for the adequacy of calculation models and simulated networks.

Key words

water supply network , hydraulic design , geoinformation system , electronic model of water and (or) wastewater system , water supply and wastewater disposal , electronic model