Source: https://guthlabs.ai/docs/instruments/fan-pump-affinity-laws-calculator/

instrument / verified-clean

# Fan/Pump Affinity Laws Calculator

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

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

## Inspectable records

[01**Overview**Purpose and lifecycle](<https://guthlabs.ai/docs/instruments/fan-pump-affinity-laws-calculator/>)[02**Mechanism**Method and assumptions](<https://guthlabs.ai/docs/instruments/fan-pump-affinity-laws-calculator/mechanism/>)[03**Implementation**Binding and validation](<https://guthlabs.ai/docs/instruments/fan-pump-affinity-laws-calculator/implementation/>)[04**Qualification**Evidence and errata](<https://guthlabs.ai/docs/instruments/fan-pump-affinity-laws-calculator/qualification/>)

## Ledger state

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

**Area**: Mechanical, Civil & Structural Engineering — Statics/Dynamics, Strength of Materials, Machine Design, Civil, HVAC, Vibration

**Tranche**: tranche-5

**Evidence ID**: t5-167

**Ledger rows**: 1

No ledger note is attached.

## Review findings

The speed formulas are acceptable idealized affinity laws under stated assumptions. The specification needs an explicit diameter formulation, explicit combined speed-and-diameter equations, and a clear distinction between head and pressure before release.

### Formula and scope findings

- The speed laws are standard only for geometrically similar operating conditions with approximately constant efficiency: Q2=Q1(N2/N1), H2=H1(N2/N1)^2, and P2=P1(N2/N1)^3.

- The phrase "analogous for diameter" is ambiguous and does not state the standard diameter exponents. For geometrically similar machines at constant speed, the usual laws are Q2/Q1=(D2/D1)^3, H2/H1=(D2/D1)^2, and P2/P1=(D2/D1)^5.

- If both speed and diameter change, the combined laws should be stated explicitly: Q2/Q1=(D2/D1)^3(N2/N1), H2/H1=(D2/D1)^2(N2/N1)^2, and P2/P1=(D2/D1)^5(N2/N1)^3.

- The output description conflates head and pressure. Head scales by the stated law; pressure requires a specified fluid density and conversion using Delta-p=rho*g*H.

### Unit assumptions

- Q1 and Q2 use the same volumetric-flow units, such as m^3/s.

- H1 and H2 are total head in the same length units, such as metres of fluid.

- If pressure is output instead of head, the fluid density rho must be known and constant; pressure is Delta-p=rho*g*H.

- P1 and P2 are the same type of power, preferably shaft or input power, and use the same power units.

- N1 and N2 are rotational speeds in the same units, such as rpm; only their ratio is used.

- D1 and D2 are corresponding diameters in the same length units; only their ratio is used.

## Boundary hardening

**BREAK_CLAIMED** · SELF_FLAGGED

A zero baseline speed produces undefined ratios and outputs, so the input must be rejected. Signed reverse speed also produces negative flow and power under literal arithmetic, exposing an unresolved directional convention and a physically invalid result.

## 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": {
    "Q1_m3_per_s": 0.5,
    "H1_m": 40,
    "P1_kW": 8,
    "N1_rpm": 1200,
    "N2_rpm": 1500
  },
  "expected_outputs": {
    "Q2_m3_per_s": 0.625,
    "H2_m": 62.5,
    "P2_kW": 15.625
  },
  "working": "Speed ratio r=N2/N1=1500/1200=1.25. Q2=0.5*1.25=0.625 m^3/s. H2=40*(1.25)^2=40*1.5625=62.5 m. P2=8*(1.25)^3=8*1.953125=15.625 kW."
}
````

## 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-tranche5/tranche5-results.json`

- `BOUNDARY_HAZARD_CATALOG.json`