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UDC 628.146

Murashev S. V., Il'ichev S. V.

Upcycle of GP-N type underground fire hydrant

Summary

GP-N underground hydrant (GOST R 53961-2010) is designed to abstract water with the help of standpipes (KPA type) from the water distribution network for firefighting. Hydrant of the given type has a fundamental defect that is autogeneration of periodic surges. The studies carried out in a hydraulic test stand arise at the beginning or at the end of the fire hydrant valve closing (at the partial ope­ning). Autogeneration of periodic surges happens in case of incorrect fire hydrant handling when the side valves of the standpipe (KPA) have been underclosed or not closed at all; or in case of hydrant being opened-closed without a standpipe. Autogeneration of surges is caused by the low pressure zone arising according to Bernulli law in the point of the maximum water velocity in the continuous steady flow. Surges can lead to the extrusion of the gasket between the fire hydrant flange and its support and hence to the damage of the fire hydrant or even of the pipeline itself to which the hydrant has been fixed in the radius of several dozen meters from the point of the hydrant installation. In order to reduce the accident rate the experts of SUE «Vodokanal of St. Petersburg» have developed, tested and patented a device that prevents surges. The engineering solution is based on blocking all possible aggregate valve plays. In order to prevent accidents related to fire hydrant and vent pipes pullout from the T-coupling the experts of SUE «Vodokanal of St. Petersburg» have developed, patented, successfully tested and put into production a compensator of the fire hydrant motion.

Key words

water supply network , water hammer , underground hydrant , motion compensator