Source: https://guthlabs.ai/docs/instruments/pump-affinity-laws-calculator/
instrument / verified-clean
# 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]()[02**Mechanism**Method and assumptions]()[03**Implementation**Binding and validation]()[04**Qualification**Evidence and errata]()
## 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**: t4-262
**Ledger rows**: 1
No ledger note is attached.
## Review findings
The speed-only equations are standard under their stated similarity assumptions, but the diameter-change claim and the undefined “speed/diameter ratio” require specification before release. The panel should explicitly distinguish speed ratio from diameter ratio and identify the type of power being predicted.
### Formula and scope findings
- The stated formulas are standard for changing rotational speed at corresponding, geometrically similar operating points, assuming the same pump geometry, fluid, and approximately constant efficiency.
- The instrument claims to handle impeller diameter changes, but no diameter variable or diameter formula is provided. For full geometric similarity, the combined scaling is Q2/Q1=(N2/N1)(D2/D1)^3, H2/H1=(N2/N1)^2(D2/D1)^2, and P2/P1=(N2/N1)^3(D2/D1)^5. Common impeller-trimming approximations use different diameter exponents and are not equivalent to the stated speed formulas.
- The phrase “new speed/diameter ratio” is ambiguous: it does not specify whether the ratio is N2/N1 or D2/D1, nor which diameter-scaling model should be used.
- The formulas do not apply to arbitrary points on a pump curve or arbitrary system operating points; the operating points must be corresponding dynamically similar points.
### Unit assumptions
- Q1 and Q2 must use the same volumetric-flow unit.
- H1 and H2 must use the same head unit, such as metres of the pumped fluid.
- P1 and P2 must use the same power unit and should be explicitly identified as shaft, brake, or input power.
- N1 and N2 must use the same rotational-speed unit; the ratio is dimensionless, so rpm may be used if both values are rpm.
- The fluid density, viscosity effects, pump geometry, and efficiency are assumed unchanged unless additional correction formulas are supplied.
- The formulas assume positive baseline speed N1 and corresponding operating points.
## Boundary hardening
**BREAK_CLAIMED** · SELF_FLAGGED
A zero baseline speed makes the required speed ratio undefined and must be rejected. The specification also leaves the speed-versus-diameter and ratio-direction conventions implicit, allowing materially different outputs if the ratio is interpreted reciprocally.
## 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": 100,
"Q_unit": "m3/h",
"H1": 40,
"H_unit": "m",
"P1": 10,
"P_unit": "kW",
"N1": 1750,
"N2": 2100,
"speed_unit": "rpm",
"ratio_type": "speed"
},
"expected_outputs": {
"Q2": 120,
"H2": 57.6,
"P2": 17.28
},
"working": "N2/N1 = 2100/1750 = 1.2. Q2 = 100 x 1.2 = 120 m3/h. H2 = 40 x (1.2)^2 = 40 x 1.44 = 57.6 m. P2 = 10 x (1.2)^3 = 10 x 1.728 = 17.28 kW."
}
````
## Related workflows
[Pipe & Pump Benchspeed scaling]()
## 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`
- `BOUNDARY_HAZARD_CATALOG.json`