Abstract
Aim: This article is aimed at analysing the validity of the selection of diameters for risers in the water-supply systems of high-rise buildings, on the basis of the regulations in force. Central focus was placed on the analysis of the throughput characteristics, accounting for their dimensions and materialrelated solutions.
Introduction: The article addresses the problems of requirements and the selection of diameters for risers in the water-supply systems of high-rise buildings. The regulations impose the use of risers with specific diameters, considered to meet the minimum requirements. In order to elaborate on whether the nominal diameters (DN) can be justified by their throughput properties and whether the use of smaller-diameter risers will contribute to substantial pressure losses, pressure drops in water-supply pipes were calculated. On the basis of the analysis, conclusions were formulated and grounds were presented for the amendment of regulations governing minimum riser diameters in high-rise buildings.
Project and methods: Artykuł opracowano w oparciu o obliczenia spadków ciśnienia w przewodach wodociągowych. Porównano wyniki obliczeń dla różnych średnic pionów wykonanych z rur stalowych ocynkowanych i z rur gładkich (miedzianych). Obliczenia przeprowadzono dwoma metodami: z wykorzystaniem wzoru Darcy-Weisbacha oraz wzoru Hazena-Williamsa.
Methodology: The article was prepared on the basis of the calculations of pressure drops in water-supply conduits. The results of the calculations were compared for various diameters of risers made of galvanised steel pipes and smooth (copper) pipes. Two calculating methods were applied: utilising (1) the Darcy-Weisbach equation and (2) the Hazen-Williams equation.
Results: A conclusion to be derived from the comparison between the pressure losses calculated for the DN 65 and DN 80 risers is that differences in the prescribed throughput values, if any, are negligible. This thesis seems to be confirmed by the results obtained in both calculation methods.
Conclusions: The calculations corroborated the thesis that the DN 80 risers in high-rise buildings can effectively be replaced by risers utilising DN 65 diameters. At a flow of 5 dm3/s, the difference between pressure losses along a 100 m section is approx. 0.3 bar. The DN 80 diameter unnecessarily increases the costs of materials and manufacturing and the burden of installation. It is advisable in respect of certain (e.g. residential) buildings that the installation-efficiency requirements be relaxed (this also applies to systems fitted with Ø33 hydrants). This would allow the use of DN 50 risers in these buildings, without compromising the safety level. In order to be introduced, the proposed changes would require the amending of the regulations in force, in particular, the Regulation of the Minister of the Interior and Administration on the fire protection of buildings, other civil structures and areas (Journal of Laws No. 109, item 719) in the part relating to water-supply systems in high-rise buildings.
Keywords: requirements for water-supply systems, residential buildings, firefighting, firefighting systems, fire protection
Type of article: review article