CFM ↔ Air Changes per Hour Converter implementation

Binding contract

This record describes what an executable surface must bind and validate. It does not claim that a public calculator, package, or production route is deployed.

Record owner

Guth Instruments

Lifecycle

verified-clean

Evidence ID

t5-155

Effect

Computation or source lookup only

Input and validation requirements

A zero room volume causes division by zero and must be rejected. Negative CFM also exposes an unresolved sign convention: signed arithmetic returns negative ACH, whereas normal HVAC usage generally expects a nonnegative airflow magnitude.

Required corrections

No binding erratum is attached to this unique-name record. Implementers must still preserve the declared units, domain, and failure behavior.

Inspectable interface fixture

The sample below is evidence for interface and validation tests, not a production implementation.

{
  "inputs": {
    "mode": "ach_from_cfm",
    "cfm": 250,
    "room_volume_ft3": 15000
  },
  "expected_outputs": {
    "ach": 1
  },
  "working": "ACH = CFM × 60 / Volume = 250 × 60 / 15000 = 15000 / 15000 = 1 ACH."
}

Other records

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