# Plumbing & Pipe Flow Calc – Flow Velocity

> Plumbing & Pipe Flow Calc – Flow Velocity is a paid API for AI agents from plumbing-calc.x402tookit.com, paid per call via x402, $0.02/call, status unknown (last checked 2026-10-29).

Calculates water velocity in feet per second from flow rate and pipe size, or calculates the flow a pipe carries at a given velocity, for copper Type L or PVC Schedule 40 pipe.

## Facts

- Endpoint: GET https://plumbing-calc.x402tookit.com/flow-velocity?utm_source=zero.xyz
- Price: $0.02/call
- Payment: x402
- Status: unknown
- Last checked: 2026-10-29
- Activations on Zero: 0
- Tags: x402
- Canonical page: https://www.zero.xyz/c/plumbing-pipe-flow-calc-flow-velocity-e5abcbfd
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_eXlHB2_5cc7RLkpynFNNy

Status and success rate cover calls made through Zero and Zero's own probes. Third-party monitors may report differently.

## How to call it through Zero

Zero handles the 402 payment challenge and records the run. With the Zero CLI installed (`npm i -g @zeroxyz/cli`):

```sh
zero fetch --capability plumbing-pipe-flow-calc-flow-velocity-e5abcbfd
```

Example prompt: What's the water velocity for a 3/4 inch copper Type L pipe flowing at 8 gpm?

## When to prefer this

Use this endpoint when you need to compute water velocity from a known flow rate and pipe size, or to find the flow rate that corresponds to a target velocity in a standard copper Type L or PVC Schedule 40 pipe. It is the right choice for residential or light commercial plumbing design, irrigation system checks, or any hydraulic calculation involving standard US pipe sizes. Prefer it over pressure-loss or pipe-sizing sibling endpoints when your primary question is specifically about velocity or flow rate in an already-known pipe.

## Known failure modes

- Missing both flowGpm and velocityFps — exactly one must be provided
- Missing both nominalSize/material and insideDiameterInches — one must be provided to identify the pipe
- Invalid material string not matching 'copper-l' or 'pvc-40' may produce an error or fall back to default
- Non-standard nominal size string that doesn't match known pipe tables may return an error
- Providing both flowGpm and velocityFps may cause ambiguity or an error
- Very large or zero flow/velocity values may return degraded results

## How this service works

Water velocity in feet per second from flow in gpm and pipe size, or the flow a pipe carries at a chosen velocity.

## Output

Returns an object with velocity in feet per second and meters per second (or flow in GPM and liters per minute if velocity was the input), along with inside diameter in inches, flow area in square feet, flow in cubic feet per second, a text summary of the result, the pipe description, and a disclaimer. Also includes degraded flag and any reasons or notes about the calculation.

## Request schema (JSON Schema)

```json
{
 "type": "object",
 "$schema": "https://json-schema.org/draft/2020-12/schema",
 "required": [
  "input"
 ],
 "properties": {
  "input": {
   "type": "object",
   "required": [
    "type",
    "method"
   ],
   "properties": {
    "type": {
     "type": "string",
     "const": "http"
    },
    "method": {
     "enum": [
      "GET"
     ],
     "type": "string"
    },
    "queryParams": {
     "type": "object",
     "required": [],
     "properties": {
      "flowGpm": {
       "type": "number",
       "description": "Flow in US gallons per minute (use flowGpm or velocityFps)"
      },
      "material": {
       "type": "string",
       "description": "copper-l or pvc-40 (default copper-l)"
      },
      "nominalSize": {
       "type": "string",
       "description": "Nominal size such as 3/4 (with material), or insideDiameterInches"
      },
      "velocityFps": {
       "type": "number",
       "description": "Velocity in feet per second, to get the flow"
      },
      "insideDiameterInches": {
       "type": "number",
       "description": "Inside diameter in inches"
      }
     }
    }
   },
   "additionalProperties": false
  },
  "output": {
   "type": "object",
   "required": [
    "type"
   ],
   "properties": {
    "type": {
     "type": "string"
    },
    "example": {
     "type": "object",
     "properties": {
      "asOf": {
       "type": [
        "null",
        "string"
       ]
      },
      "pipe": {
       "type": [
        "null",
        "string"
       ]
      },
      "source": {
       "type": [
        "null",
        "string"
       ]
      },
      "flowGpm": {
       "type": [
        "null",
        "number"
       ]
      },
      "reasons": {
       "type": [
        "array",
        "null"
       ],
       "items": {
        "type": "string"
       }
      },
      "summary": {
       "type": [
        "null",
        "string"
       ]
      },
      "verdict": {
       "type": [
        "null",
        "string"
       ]
      },
      "degraded": {
       "type": [
        "boolean",
        "null"
       ]
      },
      "disclaimer": {
       "type": [
        "null",
        "string"
       ]
      },
      "notChecked": {
       "type": [
        "array",
        "null"
       ],
       "items": {
        "type": "string"
       }
      },
      "flowAreaSquareFeet": {
       "type": [
        "null",
        "number"
       ]
      },
      "flowLitersPerMinute": {
       "type": [
        "null",
        "number
… (truncated)
```

## More

- Live health (JSON, refreshed every minute): https://www.zero.xyz/c/plumbing-pipe-flow-calc-flow-velocity-e5abcbfd/health.json
- [Zero catalog index](https://www.zero.xyz/llms.txt)
- [Other services from plumbing-calc.x402tookit.com](https://www.zero.xyz/host/plumbing-calc.x402tookit.com/llms.txt)