#drainage

Plumbing-code sizing maths as an API, computed locally and deterministically — the fixture-unit and pipe-sizing numbers a plumber, designer or inspector runs from the code book. The dfu endpoint totals drainage fixture units for a set of fixtures (IPC Table 709.1): pass a list like toilet:2,lavatory:3,shower:1,kitchen_sink:1 and it weights each by its discharge — a toilet is 3, a lavatory 1, a tub or shower 2 — for a total of 13, with a grouped full bathroom counting as 6 rather than the sum of its parts. The pipe-size endpoint gives the minimum building-drain size for a DFU load at a slope (IPC Table 710.1(1)): the smallest pipe whose capacity meets the load, so 50 DFU at a quarter-inch-per-foot fall needs a 4-inch drain, with the reminder that any drain carrying a water closet is a 3-inch minimum. The supply-gpm endpoint reads probable peak water demand off the Hunter curve: diversity means 100 supply fixture units draws only about 54 GPM, not the sum of every fixture running at once — the number you size the water service against. Everything is computed locally and deterministically, so it is instant and private. Ideal for plumbing-design and estimating apps, code-check and permit tools, MEP-engineering calculators, and trade-school aids. Pure local computation — no key, no third-party service, instant. Live, nothing stored. 3 compute endpoints. Based on the IPC — verify against the code adopted in your jurisdiction.

api.oanor.com/plumbing-api

Open-channel flow maths as an API, computed locally and deterministically with the Manning equation. The flow endpoint computes the discharge and velocity of water in an open channel — rectangular, trapezoidal, triangular or circular (a part-full pipe) — from the flow depth, the channel dimensions, the channel slope and the Manning roughness coefficient n: it works out the flow area, the wetted perimeter and the hydraulic radius, then applies Q = (1/n)·A·R^(2/3)·S^(1/2) and V = Q/A, reporting the discharge in cubic metres per second and hour, litres per second, cubic feet per second and US gallons per minute. The normal-depth endpoint reverses it: given a target discharge it solves for the normal depth by bisection and returns the resulting area, velocity and a discharge check. The roughness endpoint is a reference of typical Manning n values, from smooth PVC (0.009) and concrete (0.013) through earth and gravel to rocky natural streams (0.05); pass a material name or an explicit n. Dimensions are metric (metres by default, or cm, mm, ft, in). Everything is computed locally and deterministically, so it is instant and private. Ideal for civil and drainage engineering tools, stormwater and culvert design, irrigation and hydrology apps, and environmental modelling. Pure local computation — no key, no third-party service, instant. Live, nothing stored. 3 endpoints. This is open-channel (Manning) hydraulics; for full-pipe flow rate from diameter and velocity use a pipe-flow API.

api.oanor.com/manning-api