Source: https://guthlabs.ai/docs/instruments/sensible-latent-heat-psychrometric-calculator/implementation/

instrument implementation / implementation-contract

# Sensible & Latent Heat / Psychrometric Calculator implementation

A source-bound implementation contract for Sensible & Latent Heat / Psychrometric Calculator; deployment and executable qualification remain separate.

Status: **VERIFIED_CLEAN**Lifecycle: **implementation-contract**

## 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**: t6-128

**Effect**: Computation or source lookup only

## Input and validation requirements

At 100 °C, 100% RH, and 101.325 kPa, pv equals total pressure, so the psychrometric humidity-ratio denominator P-pv is exactly zero. The instrument must reject the state rather than return a numeric humidity ratio or enthalpy.

## 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": {
    "dry_bulb_C": 25,
    "relative_humidity": 0.5,
    "pressure_kPa_abs": 101.325,
    "airflow_CFM": 500,
    "delta_T_F": 10,
    "delta_grW_per_lb_dry_air": 20
  },
  "expected_outputs": {
    "humidity_ratio_kg_per_kg_dry_air": 0.009873,
    "enthalpy_kJ_per_kg_dry_air": 50.3,
    "dew_point_C": 13.87,
    "wet_bulb_C": 17.821,
    "Q_sensible_Btu_per_h": 5400,
    "Q_latent_Btu_per_h": 6800,
    "Q_total_Btu_per_h": 12200
  },
  "working": "pws(25)=0.61078·exp(17.2694·25/(25+237.29))≈3.167 kPa. pv=0.5·3.167=1.5835 kPa. w=0.621945·1.5835/(101.325−1.5835)=0.009873 kg/kg. h=1.006·25+0.009873·(2501+1.86·25)=25.150+0.009873·2547.5≈50.30 kJ/kg. Dew point solves pws(Tdp)=1.5835, giving Tdp≈13.87 °C. Wet-bulb bisection: initial bracket [0,25] °C; iteration 1 midpoint 12.5 °C gives saturated enthalpy below the target, so retain [12.5,25]; iteration 2 midpoint 18.75 °C gives saturated enthalpy above the target, so retain [12.5,18.75]. Continuing until interval <1e-6 °C gives Twb=17.8210 °C. Qs=1.08·500·10=5400 Btu/h. Ql=0.68·500·20=6800 Btu/h. Qt=5400+6800=12200 Btu/h."
}
````

## Other records

[01**Overview**](<https://guthlabs.ai/docs/instruments/sensible-latent-heat-psychrometric-calculator/>)[02**Mechanism**](<https://guthlabs.ai/docs/instruments/sensible-latent-heat-psychrometric-calculator/mechanism/>)[04**Qualification**](<https://guthlabs.ai/docs/instruments/sensible-latent-heat-psychrometric-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-tranche6/tranche6-results.json`