ForHosting KIT · Unit converters

Valve flow coefficient converter

100 Cv equals 86.5 Kᵥ. Convert a valve flow coefficient between the US Cv, the metric Kᵥ, Av and flow factor with fixed IEC factors, so two valve catalogs can be compared without hunting through footnotes. Free in your browser.

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Run — free How it works & API

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Worked example

If you enter

Value: 100
From: Cv
To: Kv

You get

Result: 86.5
From label: US valve flow coefficient (Cv)
To label: metric valve flow coefficient (Kv)
Kv: 86.5

A valve flow coefficient converter turns a control-valve or process-valve sizing number written in one coefficient system into another without re-deriving IEC factors or hunting catalog footnotes.

One valve, two ways of writing its capacity

Control and process valves are sized with a flow coefficient, but not every document writes it the same way. US sheets use Cv, the US valve flow coefficient, while metric sheets use Kᵥ, the metric valve flow coefficient, and some print Av or a flow factor instead. Turning one into another by hand means re-deriving the IEC factors or hunting through catalog footnotes. This converter does it with fixed factors: one Cv is 0.865 Kᵥ, so a valve rated at 100 Cv is 86.5 in the metric coefficient. The same input always gives the same result, so the figure you copy into a selection sheet or a homework answer can be checked again later.

What it converts and what it leaves out

The converter changes the coefficient system and nothing else. It does not work out the coefficient a valve needs from a process flow and a pressure drop, it does not handle mass-flow rates, and it does not give discharge coefficients for sharp-edged orifice plates on their own. A zero coefficient converts to zero in every system, while negative values are refused. The usual slip is applying the factor in the wrong direction: multiply by 0.865 to go from Cv to Kᵥ, and divide by 0.865 to go back.

Quick checks while reading valve catalogs

Open the page, enter the number and units, and copy the result without installing a spreadsheet, a unit library, or a desktop calculator pack. Source inputs follow the same retention rules as other KIT parse items, and results are safe to cache because the algorithm is fully deterministic. Authors shipping mobile apps or chatbots can map the result and formula fields directly into cards that show both the number and the conversion path engineers, technicians, and students expect on paper.

FAQ

What happens if I send an unknown unit?

The message names the field and lists supported units. Validation failures are not charged.

Is the valve flow coefficient converter free?

The browser tool runs free on your device.

How do I convert Cv to Kᵥ?

Multiply by 0.865. A valve rated at 100 Cv, the US coefficient, comes to 86.5 in the metric coefficient, and the result is the same every time you enter the same number.

How do I go back from Kᵥ to Cv?

Divide by 0.865, so 86.5 Kᵥ returns to 100 Cv. Using the factor in the wrong direction gives a wrong capacity, so check which coefficient your catalog prints before converting.

Can it size a valve from a flow rate and a pressure drop?

No. It only changes the coefficient system. Working out the coefficient a valve needs from process flow and pressure drop, mass-flow rates and orifice-plate discharge coefficients are all outside this converter.

Related tools

For developers — API access

Everything on this page is available programmatically. This section is for teams who want to wire it into their own systems; everyone else can just use the tool above.

API endpoint

POSThttps://api.kit.forhosting.com/conv/valve-flow-coefficient

Prefer to automate it? One authenticated POST creates the task; the result comes back by webhook or a signed link. The same capability also runs here on the web, by email and from Telegram — and soon from our app too.

Call it from your stack

curl -X POST https://api.kit.forhosting.com/conv/valve-flow-coefficient \
  -H "Authorization: Bearer $KIT_KEY" \
  -H "Content-Type: application/json" \
  -d '{"value":100,"from":"Cv","to":"Kv"}'

const res = await fetch("https://api.kit.forhosting.com/conv/valve-flow-coefficient", {
  method: "POST",
  headers: {
    "Authorization": `Bearer ${process.env.KIT_KEY}`,
    "Content-Type": "application/json"
  },
  body: JSON.stringify({
    "value": 100,
    "from": "Cv",
    "to": "Kv"
  })
});
const { task_id } = await res.json();

import os, requests

res = requests.post(
    "https://api.kit.forhosting.com/conv/valve-flow-coefficient",
    headers={"Authorization": f"Bearer {os.environ['KIT_KEY']}"},
    json={
    "value": 100,
    "from": "Cv",
    "to": "Kv"
},
)
task_id = res.json()["task_id"]

<?php
$res = file_get_contents("https://api.kit.forhosting.com/conv/valve-flow-coefficient", false, stream_context_create([
  "http" => [
    "method"  => "POST",
    "header"  => "Authorization: Bearer " . getenv("KIT_KEY") . "\r\nContent-Type: application/json",
    "content" => '{"value":100,"from":"Cv","to":"Kv"}',
  ],
]));
$task = json_decode($res, true);

body := bytes.NewBufferString(`{"value":100,"from":"Cv","to":"Kv"}`)
req, _ := http.NewRequest("POST", "https://api.kit.forhosting.com/conv/valve-flow-coefficient", body)
req.Header.Set("Authorization", "Bearer "+os.Getenv("KIT_KEY"))
req.Header.Set("Content-Type", "application/json")
res, _ := http.DefaultClient.Do(req)

Example request

{
  "value": 100,
  "from": "Cv",
  "to": "Kv"
}

Example response

{
  "task_id": "tsk_a1b2c3d4e5f6a1b2c3d4e5f6",
  "type": "conv.valve_flow_coefficient",
  "status": "queued",
  "_links": {
    "result": "/tasks/tsk_…/result"
  }
}

The API is asynchronous: the call returns a task_id immediately and the result arrives by webhook. Polling is capped at 1 req/s per task.

Pricing

Per request$0.002

Published price — no tokens, no invented credits. A failed task is never charged.

Errors

HTTP	Code	Meaning
`401`	`unauthorized`	Missing or invalid API key.
`402`	`insufficient_balance`	Your balance doesn't cover the task price.
`404`	`unknown_type`	That task type doesn't exist.
`429`	`rate_limited`	Too many requests. Use the webhook instead of polling.

Technical notes

The browser tool runs free on your device; the prepaid API charges $0.002 per successful item when pipelines need the same contract from servers and automation.

Supported units and how the conversion is computed

Absolute mass-flow rates, orifice discharge coefficients for sharp-edged plates alone, and required-Cv sizing from process Q and delta-P are intentionally out of scope so analysts get predictable coefficient-only results under one clear convention.

Request shape, response fields, and unknown-unit errors

The error message names the bad field and lists the supported set so clients can correct forms without guessing. Zero converts cleanly to zero in every target unit. Send a JSON body with three required fields: value as a non-negative finite number, from as the source unit string, and to as the target unit string. Missing value, non-finite numbers such as NaN or Infinity, negative values, missing unit fields, and any token that does not map to a supported unit fail with invalid_input and are not charged after the engine rejects the request. Identical inputs always yield identical JSON because the path is pure arithmetic with no randomness, no remote lookup, and no dependence on the wall clock, which makes the endpoint safe to pin in continuous-integration goldens and SDK contract tests.

Browser use, API pricing, and everyday workflows

Switch to the prepaid API when a valve-selection tool, digital twin, plant information system, or process homework checker must convert flow coefficients at scale under a stable KIT contract at $0.002 per successful item; validation failures that raise invalid_input do not consume balance after rejection.

Integration use cases

Control valve datasheets and procurement

Convert US Cv ratings from vendor PDFs into metric Kv for European line lists and RFQs without hand-written 0.865 factors or mixed-unit spreadsheets.

EPC and digital-twin pipelines

Normalize Cv, Kv, and Av when plant databases, FEED packages, and IEC instrument lists disagree on valve coefficient notation.

Homework and lab automation

Convert Cv and Kv for class problems and automated lab scripts with a prepaid, deterministic API and clear invalid_input on unknown units.

Technical questions

Which valve flow coefficient units does this converter support?

Cv (US gpm/√psi), Kv (m³/h/√bar), Av (SI m²), and flow_factor (alias of Av). Full names and common aliases are accepted; unknown units raise invalid_input.

How many Kv is one Cv?

Exactly 0.865 Kv under the IEC 60534 conventional factor Kv = 0.865 × Cv. Send value: 1, from: "Cv", to: "Kv" to see it in the result field.

What is the relationship between Kv and Av (flow factor)?

Under IEC definitions, Av (m²) = Kv / 36000. So one Kv equals about 2.7778×10⁻⁵ Av, and flow_factor is treated as the same unit family as Av.

Read the full KIT documentation →

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