Venturi Flow Meter 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-4

Evidence ID

t4-284

Ledger rows

1

No ledger note is attached.

Review findings

NEEDS_REVIEW because the exact velocity definition and the definitions of beta and A2 are absent. The honest label is empty even though the instrument should disclose its incompressible-flow limitation and that gas/compressible-flow applications require a different model or correction.

Formula and scope findings

• The stated flow formula is standard for steady, incompressible flow when beta=d2/d1 and A2 is the throat area, but beta and A2 are not defined in the specification.
• The specification promises a velocity output but provides no velocity formula or definition of which velocity is intended. Throat velocity would be v2=Q/A2; pipe inlet velocity would be v1=Q/A1, and these are different.
• The formula's applicability to compressible fluids, especially gases at substantial pressure differences, is not stated; the incompressible formula must not be presented as universally valid.

Unit assumptions

• Diameters are assumed to be in metres, producing A2 in m^2.
• Differential pressure DeltaP is assumed to be in pascals.
• Density rho is assumed to be in kg/m^3.
• The resulting volumetric flow Q is in m^3/s and throat velocity is in m/s.
• beta is assumed to be the dimensionless diameter ratio d2/d1, with d2 as throat diameter and d1 as upstream pipe diameter.
• Cd is dimensionless.

Boundary hardening

Recorded hazards

• Division by zero or invalid results occur if density is zero or negative.
• The denominator factor 1-beta^4 must be positive; beta=1 causes division by zero and beta>1 makes the square-root argument negative.
• Negative DeltaP produces an invalid square root unless signed/reverse-flow handling is explicitly implemented.
• Diameters must be positive, and the throat diameter must be smaller than the pipe diameter.
• The velocity output is ambiguous unless the instrument specifies throat velocity versus upstream pipe velocity.
• Using this incompressible formula for gases or large pressure ratios can produce materially incorrect results.
• Cd must be constrained to a physically appropriate positive range and should not be silently assumed to be 0.95-0.98 for every venturi and Reynolds-number regime.

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": {
    "pipe_diameter_d1_m": 0.1,
    "throat_diameter_d2_m": 0.05,
    "deltaP_Pa": 20000,
    "Cd": 0.97,
    "density_kg_m3": 998
  },
  "expected_outputs": {
    "Q_m3_s": 0.0124532,
    "throat_velocity_m_s": 6.34236
  },
  "working": "beta=d2/d1=0.05/0.1=0.5; beta^4=0.5^4=0.0625; 1-beta^4=0.9375. A2=pi*d2^2/4=pi*(0.05^2)/4=0.00196350 m^2. sqrt(2*DeltaP/(rho*(1-beta^4)))=sqrt(40000/(998*0.9375))=sqrt(40000/935.625)=sqrt(42.7522)=6.53851 m/s. Q=Cd*A2*sqrt(...)=0.97*0.00196350*6.53851=0.0124532 m^3/s. Throat velocity=Q/A2=0.0124532/0.00196350=6.34236 m/s."
}

Related workflows

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-tranche4/tranche4-results.json