Plumbing

Plumbing Pipe Sizing

Water-supply demand and pipe size, drainage stack, vent and building drain of a building from first principles: Hunter's probability method (NBS BMS 65, 1940) computed from each fixture's probability of use and flow, the fixture-unit weighting for mixed fixtures with the exact joint distribution beside it, the BMS 79 pressure budget (main pressure less static lift, meter and fixture minimum) with Hazen-Williams or Darcy-Weisbach friction over the standard copper or steel sizes, the stack capacity and terminal velocity of NBS Monograph 31 (Wyly and Eaton 1961) with its vent-length equation, and the building drain by Manning. The default is a small building with 10 flush-valve closets, 10 lavatories, 4 service sinks and 2 showers on a 60 lb/in² main.

1 worked example reproduced, listed on the tool page.

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