Identifiers for search
| Name | HCFC-22 (Chlorodifluoromethane) |
| Formula | CHClF₂ |
| IUPAC name | chloro(difluoro)methane |
| CAS number | 75-45-6 |
| EC number | 200-871-9 |
| UN number | 1018 — Chlorodifluoromethane |
| Transport class (ADR/RID) | 2.2 (Non-flammable, non-toxic gases) |
| PubChem CID | 6372 |
| Synonyms | Difluorochloromethane, Fluorocarbon-22, Freon® 22, Genetron® 22, Monochlorodifluoromethane, Refrigerant 22 |
Physical & chemical properties
| Molar mass | 86.47 g/mol |
| Boiling point (1 atm) | -40.9 °C |
| Melting point | -157.3 °C |
| Critical temperature | 96.2 °C |
| Critical pressure | 49.9 bar |
| Vapour pressure | 9.081 bar at 20 °C |
| Gas density | 3.9341 kg/m³ (0 °C, 1013 mbar) |
| Relative density (air = 1) | 3.03 |
| Solubility in water | 3 g/l at 25 °C |
| Appearance | gas liquefied under pressure, colourless, weak, sweetish odour, Slight odour warning effect at low concentration. |
| Odour | weak, sweetish odour |
| 1 ppm at 20 °C | 3.59 mg/m³ |
Behaviour with temperature and pressure
Boiling point -40.9 °C at 1 atm: a liquefied gas under its own vapour pressure in cylinders. Critical point 96.2 °C / 49.9 bar: below this temperature it can be stored as a liquid; cylinder pressure then equals the vapour pressure. Vapour pressure ≈ 9.081 bar at 20 °C — this is the pressure inside a cylinder or a switchgear compartment at that temperature, and it rises steeply with temperature (Clausius–Clapeyron). Relative density 3.03 (air = 1): heavier than air — accumulates in pits, cable basements and at floor level; place sensors low. Conversion at 20 °C, 1013 mbar: 1 ppm = 3.59 mg/m³; NDIR reads partial pressure, so readings scale with absolute pressure (value = reading × P/1013) and must be pressure-compensated.
// Non-combustible gas., Moderately soluble in water., Gas is heavier than air., The substance is hazardous to the ozone layer., Acute or chronic health hazards result from the substance., (see: chapter REGULATIONS).
Hazards & safety
NFPA 704
health · flammability · instability · special
GHS / CLP pictograms
| Hazard class | asphyxiant; ozone-depleting + greenhouse gas (HCFC) |
| GHS signal word | Warning |
| CLP classification | Gases under pressure, liquefied gas; H280 Hazardous to the ozone layer, Category 1; H420 |
| Hazard statements | H280: Contains gas under pressure; may explode if heated. H420: Harms public health and the environment by destroying ozone in the upperatmosphere |
| Lower / upper explosion limit | non-flammable |
| Auto-ignition temperature | 635 °C · T1 |
| Seveso III named substance | no |
Exposure limits
| EU indicative OELV (8 h TWA) | 1000 ppm · 3600 mg/m³ — Directive 2000/39/EC |
| EU IOELV short-term (15 min) | — |
| Germany AGW (TRGS 900) | — |
| Netherlands | wettelijke grenswaarde per Arboregeling bijlage XIII — SER grenswaarden database |
| NIOSH REL (USA) | TWA 1000 ppm (3500 mg/m3) ST 1250 ppm (4375 mg/m3) |
| OSHA PEL (USA) | none See Appendix G |
| IDLH | N.D. |
// Limits change: always confirm the current national value before setting an alarm. Values above were read from the EU directives / GESTIS / NIOSH pages listed in Sources.
Effect on people
Low toxicity; asphyxiant, cardiac sensitisation and mild CNS depression at high %. EU IOELV 1000 ppm. Decomposition in flames → HF, HCl, phosgene traces.
GESTIS main toxic effects: Acute:
Frostbite resulting from direct contact with liquified R22 or with gas expanded from a pressure vessel;
disturbances to the central nervous system and heart function at high concentrations,
danger of suffocation due to the displacement of oxygen
Chronic:
Very minor toxic potential (insufficient information on target organs) [2050, 7619]
Recommended monitoring
- NDIR (8.9 µm) for HCFC-22 leak monitoring on legacy plants (service with virgin R-22 banned in the EU since 2015; monitoring of the installed base continues).
- Alarm 500 ppm (IOELV 1000 ppm); floor level.
Climate & atmosphere
| GWP₁₀₀ — IPCC AR6 | 1960 |
| GWP₁₀₀ — IPCC AR4 | 1810 |
| GWP used in Reg. (EU) 2024/573 | not listed |
| Atmospheric lifetime | 11.9 years |
| Ozone depletion potential | — |
| Main IR absorption band (NDIR) | 8.8–9.2 µm (C–F stretch, ≈1100 cm⁻¹); 12.4 µm (C–Cl) |
| Note | HCFC-22 is a Montreal Protocol Annex C substance (ODP 0.055 per Protocol tables); not listed in Reg. 2024/573 Annex I (HCFCs are Annex II / ODS Regulation (EU) 2024/590). |
Regulation windows
- ODS Regulation (EU) 2024/590 — HCFC use banned (servicing since 2015); leak monitoring on legacy plants
- Workplace: EU IOELV 1000 ppm (Dir. 2000/39/EC)
Matching Tremon products
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Cite this page
Tremon Solutions (2026). HCFC-22 (CHClF₂) — properties, exposure limits, NDIR monitoring. Tremon gas reference. https://www.tremon.nl/gases/r22 (accessed 2026-09-17).
BibTeX · embed card · QR
@misc{tremon_r22_2026,
author = {Tremon Solutions},
title = {HCFC-22 (CHClF2) — properties, exposure limits, NDIR monitoring},
howpublished = {Tremon gas reference, \url{https://www.tremon.nl/gases/r22}},
year = {2026},
note = {accessed 2026-09-17}
}<a href="https://www.tremon.nl/gases/r22"><img src="https://www.tremon.nl/assets/og/r22.png" alt="HCFC-22 — Tremon gas reference" width="600"></a>
Text and tables on this page: CC BY 4.0 — copy them into your report, SOP or slide with the link above. Data were read from the primary sources listed below; check the current national limit before setting an alarm.
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Other gases
https://www.tremon.nl/gases/r22 · Tremon Solutions, Eindhoven · [email protected] · printed from the Tremon gas reference, data as of 2026-09-17 · CC BY 4.0Sources
- https://gestis-database.dguv.de/data?name=031370
- https://www.cdc.gov/niosh/npg/npgd0124.html
- https://pubchem.ncbi.nlm.nih.gov/compound/6372
- IPCC AR6 WG1 Ch.7 Supplementary Material, Table 7.SM.7 (https://www.ipcc.ch/report/ar6/wg1/downloads/report/IPCC_AR6_WGI_Chapter07_SM.pdf)
- IPCC AR4 WG1 Ch.2, Table 2.14 (https://www.ipcc.ch/site/assets/uploads/2018/02/ar4-wg1-chapter2-1.pdf)
- HITRAN/NIST IR band positions (approximate centre of the strongest band used for NDIR; https://hitran.org, https://webbook.nist.gov)
// Data compiled 2026-09-17 from the listed primary sources; null values were left blank rather than estimated.