# Data & Evidence — "The Invisible Leak" (article-26)

Downloadable datasets supporting the article **The Invisible Leak: What Happens
When You Open a Two-Phase Cooling System — And Why Nobody Is Measuring It**
(`/article-26.html`). All files are CSV (UTF-8). Figures are tagged by source
class; representative/modelled values are labelled as such. Nothing here is a
substitute for site-specific sampling or a professional environmental
assessment.

| File | Rows | What it is |
|------|------|------------|
| [`measurements-usgs-wqp-pfoa.csv`](measurements-usgs-wqp-pfoa.csv) | 5,438 | **Real water/environmental measurements.** PFOA (Perfluorooctanoic acid) results from the USGS Water Quality Portal (USGS/EPA/NWQMC cooperative) since 2020, across surface water, groundwater, sediment and tissue — reported by state agencies (Minnesota PCA, Indiana, NJDEP, Arizona DEQ, NY DEC, Delaware River Basin, etc.). PFOA is one of the two compounds under the EPA 4 ppt MCL. Public domain. Reproduce via `fetch-usgs-wqp-pfoa.sh`. |
| [`measurements-usgs-wqp-pfos.csv`](measurements-usgs-wqp-pfos.csv) | 9,230 | **Real water/environmental measurements.** PFOS results from the USGS Water Quality Portal since 2020 (both controlled-vocabulary terms combined), across surface water, groundwater, sediment and tissue. PFOS is the second compound under the EPA 4 ppt MCL. Public domain. Reproduce via `fetch-usgs-wqp-pfos.sh`. |
| [`measurements-usgs-wqp-genx-hfpo-da.csv`](measurements-usgs-wqp-genx-hfpo-da.csv) | 4,832 | **Real water/environmental measurements.** GenX (HFPO-DA) from the USGS Water Quality Portal since 2020 — the current-generation "safer" PFAS replacement, now itself EPA-regulated (10 ppt MCL, 2024). Direct analogue to the article's HFO→TFA replacement argument. Public domain. Reproduce via `fetch-usgs-wqp-genx.sh`. |
| [`measurements-noaa-hfc134a.csv`](measurements-noaa-hfc134a.csv) | 15,336 | **Real atmospheric measurements.** NOAA Global Monitoring Lab HATS flask record of HFC-134a (the dominant TFA precursor, ~100% molar yield to TFA), 16 global sites, 1994–2026, rising from ~1.8 to ~150 ppt. Public-domain US Government data — PI: S. Montzka & I. Vimont, NOAA GML. Source: `https://gml.noaa.gov/aftp/data/hats/hfcs/hfc134a_GCMS_flask.txt`. Regenerate via `convert-noaa-hfc134a.py`. |
| [`worked-model-scenarios.csv`](worked-model-scenarios.csv) | 6,000 | The article's fluid-loss model evaluated across a grid of fluid charge (100–5,000 L) × make-up rate (0.5–20 %/yr) × 3 fluids → annual loss (L, kg), replacement cost ($), t CO₂e/yr, kg TFA/yr. Reproducible via `build-worked-model.py`. |
| [`fluid-properties.csv`](fluid-properties.csv) | 11 | Per-fluid physical/chemical properties (boiling point, vapour pressure, density, GWP, atmospheric lifetime, breakdown product, PFAS status) for the Novec / Galden / Opteon / Fluorinert fluids and the R-1234yf / R-1233zd(E) TFA-yield comparison. |
| [`loss-zones.csv`](loss-zones.csv) | 7 | The loss-zone taxonomy: each fluid-escape pathway with sourced magnitude, whether it is metered, and whether it is reportable. |
| [`regulatory-thresholds.csv`](regulatory-thresholds.csv) | 14 | EPA MCL / §608 leak triggers, EU Drinking Water Directive, EU F-Gas, ECHA TFA classification, and member-state TFA limits, with status + effective date. |
| [`tfa-pfas-reference-values.csv`](tfa-pfas-reference-values.csv) | 16 | Key published TFA/PFAS concentration values and regulatory limits (Kazil 2014 rainwater, member-state limits, EU/EPA limits, HFO→TFA molar yields), each cited. |
| [`external-databases.csv`](external-databases.csv) | 13 | Pointers to the large public databases the reader can download in full (EPA UCMR 5, TRI, CompTox; USGS Water Quality Portal; NOAA GML / AGAGE; EU EEA Waterbase; NORMAN; German UBA; CA GAMA; EPA GHGRP) — with the verified portal URL, format, and what claim each supports. |

## How to use

- **Want the modelled numbers behind the article's calculators?** Open
  `worked-model-scenarios.csv` and filter to your fluid + charge.
- **Want the raw measurement data (thousands–millions of rows)?** Use
  `external-databases.csv` — those portals host the full monitoring records;
  this repo links them rather than duplicating multi-hundred-MB government files.
- **Reproduce the model:** `python3 build-worked-model.py` regenerates
  `worked-model-scenarios.csv` from the documented constants.

## Source-class tags

- **published** — peer-reviewed study or field measurement
- **vendor** — manufacturer datasheet
- **regulator** — agency rule / standard
- **modelled / representative** — computed or mid-range value chosen for the worked example

See the reference list in `/article-26.html` (refs [1]–[23]) for the full citations.

## Verification (2026-06-25)

`fluid-properties.csv`, `tfa-pfas-reference-values.csv`, `regulatory-thresholds.csv` and
`external-databases.csv` were independently source-verified. Most values were confirmed against
agency/peer-reviewed sources (a `verified_source` column carries the DOI/URL). Corrections applied:
Kazil 2014 journal (JGR Atmos., not ACP); TRI PFAS threshold (100 lb, not 25,000 lb); ECHA TFA
status (RAC opinion *adopted* June 2026); Novec breakdown products (COF₂/HF/CO₂, not PFCAs); Opteon
lifetime (~22 d EPA SNAP); Opteon GWP (~2); R-1233zd(E) lifetime (~40 d); FC-40/FC-72 GWP & lifetime
quantified; AGAGE portal URL updated. **Galden (PFPE) GWP remains unverified** — the ~10,000 figure
is commonly cited but physically disputed (PFPEs are nearly involatile); treat as an illustrative
upper bound only.