NPSH Available Calculator implementation

Binding contract

This record describes what an executable surface must bind and validate. It does not claim that a public calculator, package, or production route is deployed.

Record owner

Guth Instruments

Lifecycle

verified-clean

Evidence ID

t7-078

Effect

Computation or source lookup only

Input and validation requirements

An extreme but numerically representable input combination produces an NPSHa above the IEEE-754 binary64 finite range during addition, yielding +infinity unless the instrument validates magnitudes first. The convention probe also exposes a potentially serious 6 m error if suction lift is entered with the wrong sign.

Required corrections

No binding erratum is attached to this unique-name record. Implementers must still preserve the declared units, domain, and failure behavior.

Inspectable interface fixture

The sample below is evidence for interface and validation tests, not a production implementation.

{
  "inputs": {
    "fluid": "water",
    "temperature_C": 20,
    "atmospheric_pressure_kPa": 101.325,
    "vapor_pressure_kPa": 2.339,
    "rho_kg_m3": 998.2,
    "static_suction_head_m": 3,
    "suction_losses_m": 1.2,
    "NPSHr_m": 3.5
  },
  "expected_outputs": {
    "NPSHa_m": 11.911964,
    "margin_m": 8.411964
  },
  "reference_data": {
    "vapor_pressure_20C_kPa": 2.339,
    "atmospheric_pressure_standard_kPa": 101.325,
    "standard_gravity_m_s2": 9.80665,
    "source_convention": "Water vapor-pressure and standard-atmospheric-pressure values are widely tabulated standard values; standard gravity is the widely tabulated standard value."
  },
  "working": "Pressure difference = (101.325 - 2.339) kPa = 98.986 kPa = 98,986 Pa. Pressure head = 98,986 / (998.2 x 9.80665) = 98,986 / 9,788.99803 = 10.111964 m. NPSHa = 10.111964 + 3.000 - 1.200 = 11.911964 m. Margin = 11.911964 - 3.500 = 8.411964 m."
}

Other records

Sources and evidence

These pointers bind the page to evidence. They do not grant authority or collapse verification into deployment.

• VERIFIED_LEDGER.json
• evidence-tranche7/tranche7-results.json