#plumbing

Water-hammer (hydraulic-transient) maths as an API, computed locally and deterministically — the surge-pressure, wave-speed and valve-timing numbers a piping or plumbing engineer guards a system with. The surge endpoint applies the Joukowsky equation Δp = ρ · a · Δv: a sudden stop of the flow spikes the pressure by the fluid density × the pressure-wave speed × the velocity change — stopping 2 m/s of water at a ≈ 1200 m/s adds about 24 bar (348 psi), far above the line pressure, which is what bangs the pipes and can split fittings. The wave-speed endpoint gives that pressure-wave speed: a = √(K/ρ) in a rigid pipe (≈ 1,480 m/s for water), slowed in a real elastic pipe to √(K/ρ) ÷ √(1 + (K·D)/(E·t)) — a thin or plastic pipe gives a lower wave speed and a gentler surge, which is why PVC tolerates hammer better than steel. The critical-time endpoint gives 2L/a, the round-trip time of the wave: close a valve faster than this and you get the full Joukowsky surge, slower and the returning relief wave eats into it, so sizing closure times (or fitting a surge tank or air chamber) above the critical time is the standard cure. Everything is computed locally and deterministically, so it is instant and private. Ideal for piping- and plumbing-design tools, pump-station and pipeline-surge analysis, and hydraulic-engineering utilities. Pure local computation — no key, no third-party service, instant. Idealised single-pipe transient. 3 compute endpoints. For steady pipe pressure drop use a Darcy API; for pump head and affinity a pump API.

api.oanor.com/waterhammer-api

Radiant-floor and hydronic heating maths as an API, computed locally and deterministically — the output, tubing and flow numbers an installer or DIYer designs a warm floor with. The output endpoint gives the heat a warm floor puts out: about 2 BTU/hr per square foot for every °F the floor surface is above the room, so an 85 °F floor in a 70 °F room delivers roughly 30 BTU/hr/ft² — about 9,000 BTU/hr over 300 ft², the comfort ceiling since the floor is held at ~85 °F. The tubing endpoint gives the tube and loops for an area at a spacing: field tubing = area × 12 ÷ spacing, so 300 ft² at 9-inch spacing needs 400 feet of tube, split into loops kept under ~300 feet (two 200-foot loops) so the pump can push them. The flow endpoint gives the loop flow rate for a heat load, GPM = load ÷ (500 × ΔT) where 500 is water's constant and ΔT is the supply-to-return drop — 9,000 BTU/hr at a 20 °F ΔT wants 0.9 GPM. Everything is computed locally and deterministically, so it is instant and private. Ideal for radiant-heating and plumbing apps, hydronic-design and PEX-layout tools, HVAC contractor calculators, and DIY-build sites. Pure local computation — no key, no third-party service, instant. Live, nothing stored. 3 compute endpoints. Estimates — verify with a full heat-loss calc. For building load use an HVAC API; for pipe velocity use a flow-rate API.

api.oanor.com/radiant-api

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

Septic-system sizing as an API, computed locally and deterministically with the typical US onsite-wastewater rules of thumb. The flow endpoint estimates the design wastewater flow for a home from its number of bedrooms (assuming two people per bedroom) or an explicit occupancy, at a default 60 gallons per person per day, returning the daily flow in US gallons and litres. The tank endpoint recommends a septic tank size as the larger of a retention-based size (flow × retention days, default two days) and the typical bedroom-based code minimum (≤3 bedrooms 1,000, 4 bedrooms 1,200, 5 bedrooms 1,500, 6 bedrooms 2,000 US gallons), and tells you which one governs. The drainfield endpoint sizes the soil absorption (leach) field: it divides the daily flow by a soil loading rate — given directly or looked up from a percolation rate in minutes per inch — to get the absorption area, then divides by the trench width to get the trench length, in both imperial and metric. Everything is computed locally and deterministically, so it is instant and private. An estimating aid, not a code-stamped design — always confirm with your local health authority. Ideal for plumbing and septic-installer tools, rural real-estate and land apps, home-building and permitting calculators, and inspection software. Pure local computation — no key, no third-party service, instant. Live, nothing stored. 3 endpoints. This is septic / onsite-wastewater sizing; for storage-tank volume and fill level use a tank API.

api.oanor.com/septic-api

Water-hardness maths as an API, computed locally and deterministically. The convert endpoint converts a hardness value between all the common units — parts per million / milligrams per litre as calcium carbonate, grains per US gallon, German degrees (°dH), French degrees (°f), English or Clark degrees, and millimoles per litre — passing everything through ppm (1 gpg = 17.118 ppm, 1 °dH = 17.848, 1 °f = 10, 1 °Clark = 14.254), and classifies the result. The classify endpoint labels a value as soft, moderately hard, hard or very hard on the USGS/WHO scale. The softener endpoint sizes a water softener: from the hardness and the household water use it works out the grains of hardness removed per day and the grain capacity needed between regenerations. Everything is computed locally and deterministically, so it is instant and private. Ideal for water-treatment and plumbing tools, aquarium and pool apps, appliance and softener sizing, and home and lab software. Pure local computation — no key, no third-party service, instant. Live, nothing stored. 3 endpoints. This is water-hardness conversion; for general unit conversion use a unit-conversion API and for swimming-pool dosing use a pool API.

api.oanor.com/hardness-api