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API · /flowrate-api

Flow Rate API

healthy 4,789 Subscribers

Pipe-flow maths as an API, computed locally and deterministically. The flow endpoint relates the three quantities of pipe flow — volumetric flow rate, fluid velocity and pipe diameter — through the continuity relation Q = A·v (with A = π/4·D²): give any two and it returns the third, with the flow rate expressed in litres per second and minute, cubic metres per hour, US gallons per minute and cubic feet per minute, plus the velocity and the pipe cross-section. The reynolds endpoint computes the Reynolds number from velocity, diameter and the fluid (water, air, oil and more, or a custom kinematic viscosity) and classifies the flow as laminar, transitional or turbulent. The convert endpoint converts a flow rate between litres per second and minute, cubic metres per hour, US gallons per minute, cubic feet per minute and per second. Everything is computed locally and deterministically, so it is instant and private. It is computed in SI internally; Reynolds uses the kinematic viscosity at about 20°C. Ideal for plumbing and HVAC tools, pump and irrigation sizing, process and fluid-engineering software, and hydraulics calculators. Pure local computation — no key, no third-party service, instant. Live, nothing stored. 3 endpoints. This is fluid flow in pipes; for plain volume or unit conversion use a unit-conversion API.

#flow-rate #pipe #reynolds #hydraulics #engineering #developer-tools
api.oanor.com/flowrate-api
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Machine-readable spec so AI agents can integrate this API.

/api/flowrate-api/openapi.json
/api/flowrate-api/llms.txt

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API health

healthy
Uptime
100.00%
Server probes · 24h
Avg latency
90 ms
Server probes · 24h
Subscribers
4,789
active
Total calls
40
last 7 days
status Full status page → · 24 probes/24h

Pricing

Pick a tier — billed monthly, cancel anytime.

Free

Free

  • 11,135 calls / month
  • 2 requests / second
  • Hard cap (429 above quota, no overage)
  • 11,135 calls/month
  • 2 req/sec
  • Flow + Reynolds + convert
  • No credit card
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Starter

€12.65 /month

  • 20,750 calls / month
  • 8 requests / second
  • Hard cap (429 above quota, no overage)
  • 20.75k calls/month
  • 8 req/sec
  • Fluids + metric/imperial
  • Email support
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Pro

€32.55 /month

  • 257,500 calls / month
  • 20 requests / second
  • Hard cap (429 above quota, no overage)
  • 257.5k calls/month
  • 20 req/sec
  • HVAC / hydraulics pipelines
  • Priority support
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Mega

€70.55 /month

  • 1,330,000 calls / month
  • 50 requests / second
  • Hard cap (429 above quota, no overage)
  • 1.33M calls/month
  • 50 req/sec
  • Platform scale
  • Dedicated SLA
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Related APIs

Other APIs with overlapping tags.

Reynolds Number API

Dimensionless flow-number maths for fluid-mechanics similitude as an API, computed locally and deterministically. The reynolds endpoint computes the Reynolds number, Re = v·L/ν = ρvL/μ — the ratio of inertial to viscous forces — from the velocity, a characteristic length (pipe diameter) and either the kinematic viscosity or the density and dynamic viscosity, and classifies the flow as laminar (< 2300), transitional (2300–4000) or turbulent (> 4000). The froude endpoint computes the Froude number, Fr = v/√(g·L) — the ratio of inertia to gravity used for open-channel and ship flows — together with the critical velocity, and tells you whether the flow is subcritical (tranquil), critical or supercritical (shooting). The mach endpoint computes the Mach number, M = v/c, with the sound speed taken directly or worked out from the air temperature, c = √(γRT), and classifies the speed as subsonic, transonic, supersonic or hypersonic. Everything is computed locally and deterministically, so it is instant and private. Ideal for fluid-mechanics, aerodynamics and hydraulics tools, model-scaling and wind-tunnel similitude, pipe-flow and open-channel analysis, and engineering education. Pure local computation — no key, no third-party service, instant. Live, nothing stored. 3 endpoints. This is dimensionless-number similitude; for pipe friction pressure drop use a Darcy-Weisbach API and for open-channel uniform flow use a Manning API.

api.oanor.com/reynolds-api

O-Ring Seal API

O-ring seal-design maths as an API, computed locally and deterministically — the squeeze, gland and stretch numbers an engineer or maker designs a seal to. The squeeze endpoint gives the compression that makes the seal: squeeze = (cross-section − gland depth) ÷ cross-section, so a 0.139-inch cord in a 0.113-inch deep groove is squeezed 18.7 %, and it grades the result — roughly 10–16 % suits dynamic (reciprocating) seals and 15–30 % static ones — and, given the groove width, the gland fill percentage, which should stay under about 85 % so the rubber has room to expand from heat or fluid swell. The gland endpoint works the other way: from the cross-section and whether the seal is static or dynamic (or a target squeeze) it returns the groove depth and a width sized for about 70 % fill — typically 1.3 to 1.5 times the cross-section — plus a corner radius. The stretch endpoint checks installation: stretch = (mating diameter − o-ring ID) ÷ ID, which should stay under about 5 % on a rod because stretching thins the cross-section and steals squeeze. Everything is computed locally and deterministically, so it is instant and private. Ideal for mechanical-engineering, hydraulics, pneumatics, vacuum and product-design app developers, seal-selection and gland-design tools, and CAD plugins. Pure local computation — no key, no third-party service, instant. Inches or millimetres. Live, nothing stored. 3 compute endpoints.

api.oanor.com/oring-api

Torricelli Efflux API

Torricelli efflux and orifice-discharge maths as an API, computed locally and deterministically. The velocity endpoint applies Torricelli's law, v = √(2·g·h) — the speed at which fluid jets from an orifice under a head h equals that of a body that has fallen the same height — and returns the ideal and the actual jet velocity (corrected by a coefficient of velocity), and, if you give the orifice diameter or area, the ideal and actual volumetric discharge Q = Cd·A·√(2gh) in litres per second and minute, cubic metres per hour and US gallons per minute. The drain-time endpoint computes how long a vertical cylindrical tank takes to empty through an orifice, t = (2·A_tank)/(Cd·A_orifice·√(2g))·(√h0 − √h1), from the tank and orifice sizes, the starting head and an optional final head, with the initial flow rate. The range endpoint gives the horizontal distance a jet from a side orifice travels before it lands, x = 2·Cv·√(h·y), from the head above the orifice and the orifice's height above the ground, with the jet velocity and time of flight. The discharge and velocity coefficients default to 0.62 and 0.97 and can be overridden, as can gravity. Everything is computed locally and deterministically, so it is instant and private. Ideal for fluid-mechanics and hydraulics tools, tank-drainage, irrigation and process-engineering apps, and physics education. Pure local computation — no key, no third-party service, instant. Live, nothing stored. 3 endpoints. This is orifice efflux and tank drainage; for pipe continuity Q = A·v use a flow-rate API and for tank volume and fill level use a tank API.

api.oanor.com/torricelli-api

Open Channel Flow 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

Frequently asked questions

Quick answers about pricing, quotas, and integration.

How do I get an API key for Flow Rate API?
Sign up for free at oanor.com, generate an API key from the developer dashboard, and call Flow Rate API with the x-oanor-key header. No credit card needed for the free tier.
What's the rate limit for Flow Rate API?
Free tier allows 1 request per second. Paid plans scale up to 50 requests per second on the Mega tier. Hard limits return HTTP 429 above the quota — no surprise overage charges.
How much does Flow Rate API cost?
Flow Rate API has a free tier with 100 calls / month. Paid plans start at €12.65 / month with higher quotas and faster rate limits.
Can I cancel my subscription anytime?
Yes. Plans are billed monthly and you can cancel anytime from your billing dashboard. No long-term contracts and no cancellation fee.
Is Flow Rate API GDPR-compliant?
All requests to Flow Rate API go through our EU-based gateway. Your upstream API key never leaves our server and no personal data is shared with the upstream provider beyond the request you send.

Pick an endpoint from the list on the left to see its details and try it.

Code snippets

Sign up to get an API key, then call any path under your slug.

curl https://api.oanor.com/flowrate-api/SOME_PATH \
  -H "x-oanor-key: oanor_test_..."
const res = await fetch("https://api.oanor.com/flowrate-api/SOME_PATH", {
  headers: { "x-oanor-key": "oanor_test_..." }
});
const data = await res.json();
$ch = curl_init("https://api.oanor.com/flowrate-api/SOME_PATH");
curl_setopt($ch, CURLOPT_RETURNTRANSFER, true);
curl_setopt($ch, CURLOPT_HTTPHEADER, ["x-oanor-key: oanor_test_..."]);
$response = curl_exec($ch);
import requests
r = requests.get(
    "https://api.oanor.com/flowrate-api/SOME_PATH",
    headers={"x-oanor-key": "oanor_test_..."},
)
print(r.json())

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