{
  "slug": "r-503",
  "displayName": "R-503",
  "altSpellings": [
    "R503"
  ],
  "chemicalName": "Binary HFC/CFC azeotropic blend",
  "chemicalFormula": "R-23/R-13 (40.1/59.9)",
  "ashraeNumber": "R-503",
  "type": "cfc-blend",
  "safetyClass": "A1",
  "tradeNames": [],
  "composition": [
    {
      "component": "R-23",
      "massFraction": 0.401
    },
    {
      "component": "R-13",
      "massFraction": 0.599
    }
  ],
  "physical": {
    "boilingPointC": -87.8,
    "boilingPointF": -126,
    "critical": {
      "tempC": 19.5,
      "tempF": 67.1,
      "pressurePsia": 627,
      "pressurePsig": 612,
      "pressureKpaA": 4323,
      "pressureKpaG": 4222
    },
    "molarMassGPerMol": 87.3,
    "liquidDensityKgPerM3At25C": null,
    "temperatureGlideF": 0,
    "hasSignificantGlide": false
  },
  "environmental": {
    "odp": 0.599,
    "gwp": {
      "headline": {
        "value": 14560,
        "source": "cfr_84_64b"
      },
      "ar4": {
        "value": 14560,
        "source": "ipcc_ar4"
      },
      "ar5": {
        "value": 13299,
        "source": "ipcc_ar5"
      },
      "ar6": {
        "value": 15558,
        "source": "ipcc_ar6"
      }
    },
    "atmosphericLifetimeYears": null,
    "snapStatus": "Production banned under the Montreal Protocol (R-13 is a CFC)"
  },
  "lubricants": {
    "compatible": [
      "MO"
    ],
    "incompatible": [
      "POE"
    ],
    "notes": "Azeotrope. Historically used as the low-stage refrigerant in cascade systems for environmental test chambers and cryogenic applications. Banned for production."
  },
  "applications": [
    "Cascade low-stage refrigeration (legacy)",
    "Cryogenic and ultra-low-temperature systems (legacy)"
  ],
  "replacementOptions": [
    "r-744"
  ],
  "replaces": null,
  "regulatoryStatus": {
    "epaPhaseoutComplete": true,
    "epaPhaseoutDate": "1996-01-01",
    "aimActAffected": false,
    "snapApproved": false
  },
  "ptChart": [],
  "dataSource": {
    "ptChartSource": "Historical refrigerant — retired per Montreal Protocol (CFC-13 component banned)",
    "ptChartGeneratedAt": "2026-07-14T13:42:55.260Z",
    "ptChartVerifiedAgainst": [],
    "propertiesSource": "ASHRAE Handbook of Refrigeration 2022 (historical tables)",
    "gwpSource": "US EPA, 40 CFR 84.64(b) (100-yr); AR4/AR5/AR6 in the gwp object",
    "dataStatus": "historical-retired-refrigerant",
    "primarySources": [
      {
        "type": "historical-reference",
        "citation": "ASHRAE Handbook of Refrigeration (historical editions, pre-2010) — archived PT tables for R-503 (R-23/R-13 azeotropic CFC blend).",
        "url": "https://www.ashrae.org",
        "scope": "Reference historical data only. R-503 contained R-13 (CFC) and was phased out under the Montreal Protocol; no production since 1996."
      },
      {
        "type": "regulatory",
        "citation": "Montreal Protocol on Substances that Deplete the Ozone Layer (1987, amended).",
        "url": "https://ozone.unep.org/treaties/montreal-protocol"
      }
    ]
  },
  "indexable": false,
  "noindexReason": "pt-data-missing"
}