# Sources — PT Chart web tool

Researched 2026-10-17. All saturation pressures on this page are computed from
published refrigerant thermophysical properties — no scraped PT-chart tables,
no curve fits.

## Pressure data: CoolProp 8.0.0

Saturation pressures (bubble Q=0, dew Q=1) were generated with
[CoolProp 8.0.0](http://www.coolprop.org/) (open-source thermophysical property
library, Helmholtz-equation-of-state backend) via `~/workspace/pt-chart-mcp/core.py`,
then embedded as lookup tables (−60°F to 150°F, 1°F grid, linear interpolation).
The page's interpolation was validated against direct CoolProp calls — see
TEST_NOTES.md (worst error 0.08 psi over 96 spot checks).

- Pure fluids (R-32, R-410A, R-22, R-134a): CoolProp's built-in HEOS
  equations of state.
- R-454B: CoolProp mixture model `HEOS::R32[0.8293]&R1234YF[0.1707]`
  (ASHRAE mass fractions 68.9% R-32 / 31.1% R-1234yf converted to mole
  fractions: 68.9/52.024 = 1.3244 mol; 31.1/114.04 = 0.2727 mol;
  x_R32 = 0.8293, x_R1234yf = 0.1707).
- R-404A: CoolProp's built-in pseudo-pure/mixture model.

## Reference anchors (accuracy gate)

Spot-checked against manufacturer/published tables (see
`~/workspace/pt-chart-mcp/reference_data.py`):

| Refrigerant | Source |
|---|---|
| R-410A | Chemours OPTXLPTAC-2 (Apr 2025), via vifalio.com; 45°F field anchor (~130 psig) |
| R-32 | hudsontech.com R-32 PT chart |
| R-454B | Chemours Opteon XL41 product information bulletin (saturated-liquid vapor pressure at 25°C); Allied Air Enterprises R-454B piping guidelines Table 6 |
| R-22 | vifalio.com (Chemours-sourced table) |
| R-134a | Field-standard anchors |
| R-404A | mymortuarycooler.com (states NIST REFPROP-based, matches Arkema) |

**Rejected source:** the gesonchiller.com R-454B table is thermodynamically
impossible (claims 293/283 psig bubble/dew at 80°F; R-454B is 83 mol% R-32 and
pure R-32 saturates at 241.5 psig at 80°F — a near-ideal blend cannot sit
50 psi above its dominant pure component). Not used.

## Refrigerant reference data (info strip)

- GWP values: AR4 (R-454B 466, R-32 675, R-410A 2088, R-22 1810, R-134a 1430, R-404A 3922).
- ASHRAE safety classes: R-454B A2L, R-32 A2L, others A1.
- Typical oils: POE for HFC/HFO blends (mineral oil or alkylbenzene for R-22 legacy).
- Glide rule: dew point is the basis for superheat, bubble point for subcooling
  (standard practice for zeotropic blends; pure fluids have no glide).
- R-454B runs slightly LOWER pressures than R-410A at the same saturation
  temperature; R-32 slightly HIGHER (per the validated CoolProp models).
- R-454B subcooling can take up to 60 minutes to stabilize below ~65°F ambient
  (field guidance encoded from the MCP's validated notes).

## Diagnostic rules

The quick-diagnose decision logic is a faithful port of the validated
`diagnose()` in `~/workspace/pt-chart-mcp/core.py`: TXV target ranges
(superheat 8–12°F, subcooling 8–12°F) are industry rules of thumb —
**the equipment nameplate always governs**. Charge-pattern heuristics
(undercharge / restriction / overcharge / airflow) are standard field
diagnostics, presented as "check this first" suggestions, not certainties.

## What this page is not

Not a charging procedure and not a substitute for the manufacturer's
instructions or calibrated gauges. For certified technicians only
(EPA 608; A2L certification where required for R-454B/R-32).