Source: https://guthlabs.ai/docs/instruments/steam-quality-dryness-fraction-calculator/mechanism/

instrument mechanism / verified-clean

# Steam Quality (Dryness Fraction) Calculator mechanism

The inspectable method record for Steam Quality (Dryness Fraction) Calculator, kept separate from implementation and qualification.

Status: **VERIFIED_CLEAN**Lifecycle: **verified-clean**

## Model scope

The core quality formula is correct, but the instrument needs explicit validity checks, absolute-pressure handling, property-unit declarations, a defined interpolation scheme for both pressure and temperature inputs, and a precise definition of any additional mixture properties. The honest label should state the table source, table resolution, rounding, interpolation method, and an accuracy limit or error estimate; 'approximately saturation table resolution' is not a quantified accuracy claim.

- The formula x=(y-yf)/(yg-yf) is the standard saturated-mixture quality relation for specific enthalpy h, specific entropy s, or specific volume v, provided yf and yg are saturated-liquid and saturated-vapor values at the same saturation pressure or temperature.

- The specification does not define the interpolation variable or method. Interpolation must be explicitly defined separately for pressure-based and temperature-based lookup, and linear interpolation of rounded table values is only an approximation.

- The claimed output 'mixture properties' is underspecified. Quality alone does not define which additional properties are returned or the equations used to calculate them.

- The specification does not state whether h, s, and v are mass-specific quantities; the formula is invalid if mixed with molar or total properties.

- The formula applies only inside the two-phase saturation dome, including the limiting states x=0 and x=1. It is not valid for compressed liquid, superheated vapor, or supercritical states.

## Units and conventions

- Temperature inputs are in degrees Celsius for the temperature-based vectors; saturation-table interpolation is performed in degrees Celsius.

- Pressure inputs are absolute pressure, not gauge pressure; the pressure-based vector uses 1.000 MPa absolute.

- Specific enthalpy h is in kJ/kg, and specific volume v is in m^3/kg. Specific entropy, if supported, must use one consistent mass-specific unit such as kJ/(kg K).

- Saturated-liquid and saturated-vapor reference values must use the same pressure or temperature and the same property units as the measured input.

- The tabulated values below are rounded standard steam-table values; calculations use the displayed rounded values exactly.

## Inspectable vector

One of 4 source-bound review vectors:

````
{
  "inputs": {
    "temperature_C": 100,
    "property": "specific enthalpy",
    "h_kJ_per_kg": 419.04
  },
  "expected_outputs": {
    "quality_x": 0,
    "phase_state": "saturated liquid boundary",
    "saturation_pressure_kPa": 101.325,
    "mixture_specific_enthalpy_kJ_per_kg": 419.04
  },
  "reference_data": {
    "temperature_C": 100,
    "saturation_pressure_kPa": 101.325,
    "hf_kJ_per_kg": 419.04,
    "hg_kJ_per_kg": 2675.5,
    "source_convention": "IAPWS-IF97 standard steam-table values, rounded to the displayed precision; 100 C saturation pressure is the widely memorized standard value 101.325 kPa"
  },
  "working": "At 100 C, yf=hf=419.04 kJ/kg and yg=hg=2675.5 kJ/kg. x=(h-hf)/(hg-hf)=(419.04-419.04)/(2675.5-419.04)=0/2256.46=0.000000. Therefore x=0 and the state is saturated liquid. The saturation pressure is the table value 101.325 kPa."
}
````

## Failure boundary

**BREAK_CLAIMED** · SELF_FLAGGED

The critical-point vector makes hg - hf exactly zero and the quality expression becomes 0/0. An implementation without an explicit critical-point and zero-denominator guard can produce NaN, an exception, or an invalid quality. The branch and unit vectors also expose required rejection and convention checks outside the two-phase dome.

## Other records

[01**Overview**](<https://guthlabs.ai/docs/instruments/steam-quality-dryness-fraction-calculator/>)[03**Implementation**](<https://guthlabs.ai/docs/instruments/steam-quality-dryness-fraction-calculator/implementation/>)[04**Qualification**](<https://guthlabs.ai/docs/instruments/steam-quality-dryness-fraction-calculator/qualification/>)

## 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`

- `BOUNDARY_HAZARD_CATALOG.json`