Steam Table Property Lookup mechanism

Model scope

The core method is standard, but the empty honest_label and unspecified interpolation/phase/cp conventions require review before catalog approval. The label should state the supported pressure-temperature range, whether results are exact IF97 evaluations or interpolated table estimates, the allowed quality range, and that cp at two-phase or saturation states is undefined or path-dependent unless a specific derivative convention is supplied.

• IAPWS-IF97 is a valid standard formulation for water and steam properties, but the specification does not define the region-selection logic, saturation-boundary handling, or validity limits.
• P and T alone do not uniquely define a two-phase state; quality x or an equivalent phase specification is required when the state lies in the saturation dome.
• Table interpolation is not a uniquely defined algorithm. The specification must state the interpolation variables, interpolation order, independent-variable grid, and whether interpolation is permitted across phase or IF97-region boundaries.
• cp is not normally supplied as a basic saturated-water/steam table property. At saturation, cp is path-dependent or undefined as a single two-phase equilibrium property; IF97 cp should be explicitly defined as the isobaric derivative for a single-phase state.
• The instrument claims to compute h, s, v, u, and cp, but the specification does not state the reference state and unit conventions expected for h, u, and s.

Units and conventions

• Pressure is entered and reported in kPa unless explicitly labeled otherwise; 1 kPa·m^3/kg = 1 kJ/kg for the Pv term.
• Temperature is in degrees Celsius for table lookup; IF97 internally requires absolute temperature in kelvin.
• Specific enthalpy h and internal energy u are in kJ/kg.
• Specific entropy s and heat capacity cp are in kJ/(kg·K).
• Specific volume v is in m^3/kg.
• Quality x is dimensionless, with x=0 saturated liquid and x=1 saturated vapor.

Inspectable vector

One of 4 source-bound review vectors:

{
  "inputs": {
    "pressure_kPa": 101.325,
    "temperature_C": 100,
    "quality": 0,
    "state_specification": "saturated liquid"
  },
  "expected_outputs": {
    "h_kJ_per_kg": 419.04,
    "s_kJ_per_kg_K": 1.3072,
    "v_m3_per_kg": 0.001043,
    "u_kJ_per_kg": 418.9343,
    "cp_kJ_per_kg_K": 4.216,
    "phase_region": "saturation boundary, saturated liquid"
  },
  "reference_data": {
    "pressure_kPa": {
      "value": 101.325,
      "source_convention": "widely tabulated standard value; water saturation pressure at 100 C"
    },
    "temperature_C": {
      "value": 100,
      "source_convention": "widely tabulated standard value; normal boiling point of water at 101.325 kPa"
    },
    "hf_kJ_per_kg": {
      "value": 419.04,
      "source_convention": "IAPWS/IF97 standard steam-table value"
    },
    "sf_kJ_per_kg_K": {
      "value": 1.3072,
      "source_convention": "IAPWS/IF97 standard steam-table value"
    },
    "vf_m3_per_kg": {
      "value": 0.001043,
      "source_convention": "IAPWS/IF97 standard steam-table value"
    },
    "cp_liquid_kJ_per_kg_K": {
      "value": 4.216,
      "source_convention": "widely tabulated standard value near 100 C"
    }
  },
  "working": "At 100 C and 101.325 kPa, x=0 selects saturated liquid. h = hf = 419.04 kJ/kg. s = sf = 1.3072 kJ/(kg K). v = vf = 0.001043 m^3/kg. u = h - Pv = 419.04 - (101.325)(0.001043) = 419.04 - 0.105682 = 418.9343 kJ/kg. cp is reported from the liquid-property table as 4.216 kJ/(kg K). This is an exact normal-boiling-point table entry and an edge case at x=0."
}

Failure boundary

BREAK_CLAIMED · SELF_FLAGGED

The specification exposes two hard hazards: P=0 produces an undefined result and must be rejected, while the permitted P/T input does not define pressure units, absolute-versus-gauge convention, or quality at saturation. Consequently the same displayed input can select different regions or fail to determine unique h, s, v, u, and cp values.

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
• BOUNDARY_HAZARD_CATALOG.json