Pressure Loss

{
  "asOf": "2026-10-12T01:57:25.778Z",
  "cFactor": 140,
  "degraded": false,
  "disclaimer": "Screening signal computed from the named public source. Not financial, legal or investment advice; provided as is. Verify at the source before acting.",
  "feetOfHeadLoss": 25.56,
  "flowGpm": 10,
  "insideDiameterInches": 0.785,
  "kilopascalsLoss": 76.3,
  "lengthFeet": 100,
  "lossIfFlowDoubled": 39.951,
  "notChecked": [
    "fittings, valves, meters and elevation change (add 1 psi per 2.31 ft of rise)",
    "water temperature and very high or low velocities where the formula is less accurate",
    "…1 more"
  ],
  "pipe": "3/4 in copper-l",
  "psiPer100Feet": 11.067,
  "psiPerFoot": 0.11067,
  "reasons": [
    "Hazen-Williams suits water at ordinary temperatures in pipes above 2 inches; it is a conventional estimate for smaller pipes.",
    "Doubling the flow multiplies the loss by about 3.6."
  ],
  "source": "computed locally (Hazen-Williams: psi/ft = 4.52 Q^1.852 / (C^1.852 d^4.8655))",
  "summary": "3/4 in copper-l at 10 gpm over 100 ft loses 11.07 psi (11.07 psi per 100 ft).",
  "totalPsiLoss": 11.067,
  "verdict": "COMPUTED"
}

# bash or zsh: see the payment challenge. Nothing is charged.
curl -sS -g -i 'https://plumbing-calc.x402tookit.com/pressure-loss?flowGpm=10&lengthFeet=100&material=copper-l&nominalSize=3%2F4'

# x402 v2 sends the challenge base64-encoded in the PAYMENT-REQUIRED header (v1 sends it in the body).
# To read the header:
curl -sS -g -o /dev/null -D - 'https://plumbing-calc.x402tookit.com/pressure-loss?flowGpm=10&lengthFeet=100&material=copper-l&nominalSize=3%2F4' \
  | grep -i '^payment-required:' | cut -d' ' -f2 | tr -d '\r' | base64 --decode

// npm i @x402/fetch @x402/evm viem
import { wrapFetchWithPayment, x402Client } from "@x402/fetch";
import { registerExactEvmScheme } from "@x402/evm/exact/client";
import { privateKeyToAccount } from "viem/accounts";

// Pays at most $0.02 per call.
const client = new x402Client().setSpendControls({ maxAmountPerPayment: "$0.02" });
registerExactEvmScheme(client, { signer: privateKeyToAccount(process.env.EVM_PRIVATE_KEY) });
const pay = wrapFetchWithPayment(fetch, client);

// Not sure it's safe to pay? ToolVet checks it first for $0.005. Pay for that from a separate
// client: this one is capped at $0.02 per payment. GET https://toolvet.app/api/v1/check?url=https%3A%2F%2Fplumbing-calc.x402tookit.com%2Fpressure-loss
const res = await pay("https://plumbing-calc.x402tookit.com/pressure-loss?flowGpm=10&lengthFeet=100&material=copper-l&nominalSize=3%2F4");
console.log(res.status, await res.text());

# pip install "x402[requests,evm]"
import os
from eth_account import Account
from x402 import x402ClientSync
from x402.http.clients import x402_requests
from x402.mechanisms.evm import EthAccountSigner
from x402.mechanisms.evm.exact.register import register_exact_evm_client

# Pays at most $0.02 per call.
client = x402ClientSync().set_spend_controls({"max_amount_per_payment": "$0.02"})
register_exact_evm_client(client, EthAccountSigner(Account.from_key(os.environ["EVM_PRIVATE_KEY"])))

with x402_requests(client) as session:
    res = session.get("https://plumbing-calc.x402tookit.com/pressure-loss?flowGpm=10&lengthFeet=100&material=copper-l&nominalSize=3%2F4")
    print(res.status_code, res.text)