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

instrument mechanism / verified-clean

# Fan/Pump Affinity Laws Calculator mechanism

The inspectable method record for Fan/Pump Affinity Laws Calculator, kept separate from implementation and qualification.

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

## Model scope

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.

- 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.

## Units and conventions

- 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.

## Inspectable vector

One of 4 source-bound review vectors:

````
{
  "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."
}
````

## Failure boundary

**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.

## Other records

[01**Overview**](<https://guthlabs.ai/docs/instruments/fan-pump-affinity-laws-calculator/>)[03**Implementation**](<https://guthlabs.ai/docs/instruments/fan-pump-affinity-laws-calculator/implementation/>)[04**Qualification**](<https://guthlabs.ai/docs/instruments/fan-pump-affinity-laws-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-tranche5/tranche5-results.json`

- `BOUNDARY_HAZARD_CATALOG.json`