{
  "capability_id": "physics.fluid.npsh",
  "tool_id": "npsh",
  "engine": "npsh",
  "calculation_version": "1.0.0",
  "generated_at": "2026-09-17T06:35:12.144Z",
  "engine_build": "2026-09-17",
  "test_count": 14,
  "passed": 14,
  "failed": 0,
  "tests_summary": {
    "golden": {
      "total": 2,
      "passed": 2
    },
    "boundary": {
      "total": 7,
      "passed": 7
    },
    "property": {
      "total": 5,
      "passed": 5
    }
  },
  "engine_tested": true,
  "expert_reviewed": false,
  "internally_reviewed": false,
  "review_kind": null,
  "source_checked": true,
  "reviewed_by": null,
  "reviewer_role": null,
  "last_reviewed": null,
  "expert_review": {
    "status": "optional_not_performed",
    "reviewer": null,
    "scope": [
      "formula",
      "input semantics",
      "assumptions",
      "limitations",
      "sources",
      "tests"
    ],
    "note": "Domain expert review is optional under CVP (CVP-EXP-01). Absence does not block CVP Verified. See Review policy for supplemental domain assurance."
  },
  "internal_review": {
    "status": "not_applicable",
    "reviewer": null
  },
  "page": "https://www.calculatorx.com/calc/physics/npsh",
  "api": "https://www.calculatorx.com/api/v1/calc/npsh",
  "schema_input": "https://www.calculatorx.com/schemas/physics.fluid.npsh.input.json",
  "schema_output": "https://www.calculatorx.com/schemas/physics.fluid.npsh.output.json",
  "assumptions": [
    "NPSHa = (p_s − p_v)/(ρ g) + v_s²/(2g) + z_s; pressures absolute; SI",
    "Open tank: p_s=p_atm (default 101325 Pa), z_s=z−hf, v_s=0; hf is an input",
    "Not pump power, not orifice, not weir, not Q=Av, not Darcy, not a catalog NPSHr curve, not steam p_v(T)"
  ],
  "limitations": [
    "NPSHa = (p_s − p_v)/(ρ g) + v_s²/(2g) + z_s; pressures absolute; SI",
    "Open tank: p_s=p_atm (default 101325 Pa), z_s=z−hf, v_s=0; hf is an input",
    "Not pump power, not orifice, not weir, not Q=Av, not Darcy, not a catalog NPSHr curve, not steam p_v(T)"
  ],
  "boundary_conditions": [
    "missing p_v, or missing both p_s and z → MISSING_REQUIRED_INPUT",
    "margin mode without NPSHr → MISSING_REQUIRED_INPUT",
    "hf, v_s, p_v, or NPSHr < 0 → VALUE_OUT_OF_RANGE",
    "rho, g, or p_atm ≤ 0 → VALUE_MUST_BE_POSITIVE",
    "p_s with z/hf/p_atm, Q/H/P/η, C_d, A, L, f, or gauge pressure → MIXED_INPUT_ENCODING",
    "pump, orifice, weir, Manning, Darcy, or Q=Av as mode → INVALID_MODE"
  ],
  "sources": [
    {
      "title": "ISO 9906 — Rotodynamic pumps — Hydraulic performance acceptance tests",
      "section": "NPSH available at the pump datum",
      "url": "https://www.iso.org/standard/57605.html",
      "supports": "NPSHa from absolute suction pressure, vapor pressure, and velocity head",
      "kind": "standard"
    },
    {
      "title": "ANSI/HI 1.3 — Rotodynamic Pumps for Design and Application",
      "section": "NPSH available and required",
      "url": "https://www.pumps.org/",
      "supports": "NPSHa from suction-tank static head minus suction-line losses; NPSHr from the manufacturer",
      "kind": "standard"
    }
  ],
  "methods": [],
  "fingerprint": "sha256:d5b3082a766fb3f71a877c6f768057b8b8d12c7a39d98164672515b31dadfe70",
  "tests": [
    {
      "id": "golden-npsh-tank",
      "ok": true,
      "kind": "golden",
      "inputs": {
        "p_v": 2339,
        "z": 2,
        "hf": 0.5
      },
      "expect": {
        "NPSHa": 11.59376290578332,
        "kind": "open_tank",
        "mode": "available",
        "model": "npsh"
      },
      "expectWarning": null,
      "actual": {
        "mode": "available",
        "kind": "open_tank",
        "NPSHa": 11.59376290578332,
        "p_atm": 101325,
        "p_v": 2339,
        "z": 2,
        "hf": 0.5,
        "rho": 1000,
        "g": 9.80665,
        "model": "npsh"
      },
      "tol": 1e-10
    },
    {
      "id": "golden-npsh-flange",
      "ok": true,
      "kind": "golden",
      "inputs": {
        "p_s": 90000,
        "p_v": 2339,
        "v_s": 2
      },
      "expect": {
        "NPSHa": 9.142877537181402,
        "kind": "flange",
        "model": "npsh"
      },
      "expectWarning": null,
      "actual": {
        "mode": "available",
        "kind": "flange",
        "NPSHa": 9.142877537181402,
        "p_s": 90000,
        "p_v": 2339,
        "v_s": 2,
        "z_s": 0,
        "rho": 1000,
        "g": 9.80665,
        "model": "npsh"
      },
      "tol": 1e-10
    },
    {
      "id": "boundary-npsh-margin",
      "ok": true,
      "kind": "boundary",
      "inputs": {
        "mode": "margin",
        "p_v": 2339,
        "z": 2,
        "hf": 0.5,
        "NPSHr": 4
      },
      "expect": {
        "NPSHa": 11.59376290578332,
        "NPSHr": 4,
        "margin": 7.59376290578332,
        "cavitation": false,
        "model": "npsh"
      },
      "expectWarning": null,
      "actual": {
        "mode": "margin",
        "kind": "open_tank",
        "NPSHa": 11.59376290578332,
        "p_atm": 101325,
        "p_v": 2339,
        "z": 2,
        "hf": 0.5,
        "rho": 1000,
        "g": 9.80665,
        "model": "npsh",
        "NPSHr": 4,
        "margin": 7.59376290578332,
        "cavitation": false
      },
      "tol": 1e-10
    },
    {
      "id": "boundary-npsh-missing",
      "ok": true,
      "kind": "boundary",
      "inputs": {
        "p_v": 2339
      },
      "expectError": "MISSING_REQUIRED_INPUT",
      "code": "MISSING_REQUIRED_INPUT",
      "error": "Need flange p_s or open-tank z, plus p_v"
    },
    {
      "id": "boundary-npsh-hf",
      "ok": true,
      "kind": "boundary",
      "inputs": {
        "p_v": 2339,
        "z": 2,
        "hf": -0.1
      },
      "expectError": "VALUE_OUT_OF_RANGE",
      "code": "VALUE_OUT_OF_RANGE",
      "error": "hf must be ≥ 0"
    },
    {
      "id": "boundary-npsh-mixed",
      "ok": true,
      "kind": "boundary",
      "inputs": {
        "p_s": 90000,
        "p_v": 2339,
        "z": 2
      },
      "expectError": "MIXED_INPUT_ENCODING",
      "code": "MIXED_INPUT_ENCODING",
      "error": "Use flange p_s or open-tank z (and optional p_atm, hf), not both"
    },
    {
      "id": "boundary-npsh-pump-q",
      "ok": true,
      "kind": "boundary",
      "inputs": {
        "p_v": 2339,
        "z": 2,
        "Q": 0.05
      },
      "expectError": "MIXED_INPUT_ENCODING",
      "code": "MIXED_INPUT_ENCODING",
      "error": "NPSH does not take Q. That is pump power or Q=Av"
    },
    {
      "id": "boundary-npsh-cd",
      "ok": true,
      "kind": "boundary",
      "inputs": {
        "p_v": 2339,
        "z": 2,
        "Cd": 0.61
      },
      "expectError": "MIXED_INPUT_ENCODING",
      "code": "MIXED_INPUT_ENCODING",
      "error": "NPSH does not take C_d. That is orifice or weir"
    },
    {
      "id": "boundary-npsh-pump-mode",
      "ok": true,
      "kind": "boundary",
      "inputs": {
        "p_v": 2339,
        "z": 2,
        "mode": "power"
      },
      "expectError": "INVALID_MODE",
      "code": "INVALID_MODE",
      "error": "mode must be available|margin. Not pump, orifice, weir, Manning, Darcy, or Q=Av"
    },
    {
      "id": "property-npsh-tank",
      "ok": true,
      "kind": "property",
      "detail": "(p_atm−p_v)/ρg+z−hf",
      "expect": 11.59376290578332,
      "actual": 11.59376290578332
    },
    {
      "id": "property-npsh-flange",
      "ok": true,
      "kind": "property",
      "detail": "(p_s−p_v)/ρg+v²/2g",
      "expect": 9.142877537181402,
      "actual": 9.142877537181402
    },
    {
      "id": "property-npsh-z",
      "ok": true,
      "kind": "property",
      "detail": "z increases NPSHa",
      "expect": true,
      "actual": true
    },
    {
      "id": "property-npsh-pv",
      "ok": true,
      "kind": "property",
      "detail": "p_v decreases NPSHa",
      "expect": true,
      "actual": true
    },
    {
      "id": "property-npsh-margin",
      "ok": true,
      "kind": "property",
      "detail": "margin=NPSHa−NPSHr",
      "expect": 7.59376290578332,
      "actual": 7.59376290578332
    }
  ],
  "tier": "engine_tested",
  "verification": {
    "tests": {
      "passed": 14,
      "total": 14,
      "golden": 2,
      "boundary": 7,
      "property": 5
    },
    "contract_checks": {
      "passed": 4,
      "total": 4
    }
  },
  "evidence_core_generated_at": "2026-09-17T03:58:19.307Z",
  "rendered_at": "2026-09-17T06:35:12.144Z",
  "release_integrity": {
    "status": "verified",
    "scope": "workspace",
    "production_attestation_required": true,
    "calculation_version": "1.0.0",
    "artifacts": {
      "engine": "1.0.0",
      "page": "1.0.0",
      "capability": "1.0.0",
      "evidence": "1.0.0",
      "input_schema": "1.0.0",
      "output_schema": "1.0.0",
      "mcp_contract": "1.0.0"
    },
    "digests": {
      "input_schema_sha256": "4d99adcedf50829825531778ad1444c70c70aea4e5079b77a91f01e7814a4e34",
      "output_schema_sha256": "38d11ab23ad0d1d705d2d3d584e0fa3b4a702f6486b4eaa3ae638c46b13a9a24",
      "evidence_sha256": "f4a669ed986960f6dc5da0b6b61068a7d664cdecb177b8c400408d4487f643b9",
      "evidence_core_sha256": "f4a669ed986960f6dc5da0b6b61068a7d664cdecb177b8c400408d4487f643b9",
      "capability_sha256": "1635cd30432d884f4b408689af8d9f28ea3c3cdd7e01e7eaa50c2ed950c3c74c",
      "engine_sha256": "577dd02827ddc989c9ec83548106b0de2da132cdaad4c2e72f4dc05cde6f3e07",
      "mcp_contract_sha256": "a0951a99ea7017485ae852239b46888380ab942a7571f6a90cc299bd18753be2"
    },
    "contract_checks": {
      "total": 4,
      "passed": 4,
      "failed": 0,
      "items": [
        {
          "id": "release-artifacts-aligned",
          "status": "pass",
          "detail": "1.0.0"
        },
        {
          "id": "schema-valid-input-executes",
          "status": "pass"
        },
        {
          "id": "engine-success-output-validates-schema",
          "status": "pass"
        },
        {
          "id": "schema-rejects-incomplete-input",
          "status": "pass"
        }
      ]
    },
    "report": "https://www.calculatorx.com/.well-known/calculatorx-release-integrity.json"
  }
}