Experimental investigation of a vortex-flow restrictor: Rain-blocker performance tests

Yovanni A. Cataño-Lopera, Andrew R. Waratuke, Marcelo Horacio Garcia

Research output: Contribution to journalArticlepeer-review


Flow restrictors, or rain blockers, are commonly used at inlets of storm-drain networks to limit the peak flow entering storm sewers. This reduces the likelihood of the sewer system becoming hydraulically overloaded, thus preventing sewer backups and residential flooding. The vortex-flow restrictor limits flow by forcing flow through a helicoidal chamber followed by sudden expansions and contractions that create high levels of turbulence. The high turbulence produced in a vortex-flow restrictor limits flow rates much more than a simple orifice, while maintaining a relatively large flow opening that can reduce the chances of clogging. Hydraulic tests were conducted with a vortex-flow restrictor (FR Type I) as well as a modified version in which the vortex chamber was removed (FR Type II), in which case the restrictor works a simple orifice plate. Discharge coefficients were calculated for the tested flow restrictor configurations and were compared to the case in which no flow restrictor was in place.

Original languageEnglish (US)
Article number007008QHY
Pages (from-to)528-533
Number of pages6
JournalJournal of Hydraulic Engineering
Issue number8
StatePublished - Aug 2010


  • Experiments
  • Flow restrictor
  • Rain blockers
  • Urban hydrology

ASJC Scopus subject areas

  • Civil and Structural Engineering
  • Water Science and Technology
  • Mechanical Engineering


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