Minor Losses (K-factor) Calculator

Inspectable records

Ledger state

The current ledger marks this instrument verified clean within the source-bound verification corpus.

Area

Thermodynamics, Fluids & Aero

Tranche

tranche-7

Evidence ID

t7-070

Ledger rows

1

No ledger note is attached.

Review findings

The core head-loss formula is standard, and the equivalent-length formula is standard under the stated Darcy-friction and common-diameter assumptions. Verdict is NEEDS_REVIEW because D, Darcy friction factor, fluid density, fitting geometry/table-selection parameters, and the pressure-versus-head output definition are missing. The honest_label field is empty; it should disclose that K values are representative table values and that pressure loss requires fluid density.

Formula and scope findings

• hL = K·V²/(2g) is the standard minor-loss head formula, but for a fitting list the implementation must use K_total = ΣK_i when all fittings share the same velocity; otherwise it must calculate Σ(K_i·V_i²/(2g)) for fitting-specific velocities.
• L_eq = K·D/f is standard only when f is the Darcy friction factor and the same pipe diameter and friction-factor convention apply. The required inputs omit D and f.
• The specification claims pressure loss as an output, but the listed formulas produce head loss. Pressure loss additionally requires Δp = ρg hL, with fluid density ρ supplied or explicitly assumed.
• K factors are not unique without fitting geometry, valve position, connection type, diameter ratio, and the chosen table convention; a generic common-fitting lookup can therefore be ambiguous.

Unit assumptions

• V is mean pipe velocity in m/s.
• D is internal pipe diameter in m.
• g = 9.80665 m/s², the standard gravity value.
• hL and L_eq are reported in m of fluid and m of equivalent pipe length, respectively.
• K is dimensionless.
• f is the Darcy-Weisbach friction factor, dimensionless, not the Fanning friction factor.

Boundary hardening

BREAK_CLAIMED · SELF_FLAGGED

The equivalent-length output requires D and f, but the declared input list only specifies fitting K values and V. In addition, f=0 produces an undefined result and must be explicitly rejected. Without validation and without required D and f inputs, the instrument cannot reliably compute every advertised output.

Errata and corrections

No applied erratum is attached to this unique-name record.

Inspectable example

4 review vectors are recorded. One source-bound sample is shown below.

{
  "inputs": {
    "fitting_list": [
      {
        "name": "sharp-edged entrance",
        "K": 0.5
      }
    ],
    "V_m_per_s": 2,
    "D_m": 0.1,
    "Darcy_friction_factor": 0.02,
    "g_m_per_s2": 9.80665
  },
  "expected_outputs": {
    "total_K": 0.5,
    "total_minor_head_loss_m": 0.101972,
    "equivalent_length_m": 2.5
  },
  "reference_data": {
    "table_rows": [
      {
        "fitting": "sharp-edged entrance",
        "K": 0.5,
        "source_convention": "widely tabulated standard value; Crane TP-410-style loss-coefficient convention"
      }
    ],
    "gravity_m_per_s2": 9.80665,
    "gravity_source_convention": "widely tabulated standard value; standard gravity"
  },
  "working": "K_total = 0.5. 2g = 2 × 9.80665 = 19.6133 m/s². V² = 2.0² = 4. hL = 0.5 × 4 / 19.6133 = 2 / 19.6133 = 0.101972 m. L_eq = K_total × D / f = 0.5 × 0.1 / 0.02 = 0.05 / 0.02 = 2.5 m."
}

Related workflows

No source-defined multi-instrument workflow membership is recorded.

Sources and evidence

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

• VERIFIED_LEDGER.json · VERIFIED_CLEAN
• evidence-tranche7/tranche7-results.json
• BOUNDARY_HAZARD_CATALOG.json