Lapse in Appropriations
For workplace safety and health, please call 800-321-6742; for mine safety and health, please call 800-746-1553; for Job Corps, please call 800-733-5627 and for Wage and Hour, please call 866-487-9243 (866-4-US-WAGE). This website is currently not being updated due to the suspension of Federal government services. The last update to the site was 10/1/2025. Updates to the site will start again when the Federal government resumes operations.
HYDROGEN FLUORIDE†
| CAS # | 7664-39-3 |
|---|---|
| Formula |
HF (aqueous) |
| Synonyms |
anhydrous hydrofluoric acid, HF-A |
| Physical description | Colorless gas or fuming liquid (below 67°F) with a strong, irritating odor. | ||
|---|---|---|---|
| Boiling point | 67°F | Molecular weight | 20 |
| Freezing point/melting point | -118°F | Vapor pressure | 783 mmHg |
| Flash point | Vapor density | 1.86 | |
| Specific gravity | 1 | Ionization potential | 15.98 eV |
| Lower explosive limit (LEL) | Upper explosive limit (UEL) | ||
| NFPA health rating | 4 | NFPA fire rating | 0 |
| NFPA reactivity rating | 1 | NFPA special instruction | |
| Vapor hazard ratio (VHR) | |||
| Historical exceedance percentage | |||
| Target organs | |||
| Analyte code (IMIS no.) | 1460 |
|---|---|
| Sampling group | |
| Sampler/Sampling media | Mixed cellulose ester filter (MCEF) 0.8 micron (37 mm) and filter spacer with Na₂CO₃ impregnated backup pad, in a 3-piece cassette [SKC 225-9001] |
| Sampling time* | 60 min |
| Sampling volume (TWA)* | 90 L |
| Sampling flow rate (TWA)* | 1.5 L/min |
| Sampling volume (STEL/Peak/C)* | 22.5 L |
| Sampling flow rate (STEL/Peak/C)* | 1.5 L/min |
| Analytical method instruments | ISE |
| Method reference | OSHA ID-110 (fully validated) |
| Notes | Submit as a separate sample (Particulate F- on MCEF, HF on impregnated backup pad). The filter and filter spacer reside in one section while the impregnated backup pad is in another section of a 3-piece polystyrene cassette. The filter and backup pad should not have physical contact with one another. When analysis of a compound is requested, an analysis is performed for fluoride (F-) and reported as the compound. Hydrogen fluoride is collected on a Na₂CO₃ impregnated backup pad. |
| Special requirements |
* All sampling instructions above are recommended guidelines for OSHA Compliance Safety and Health Officers (CSHOs), please see the corresponding OSHA method reference for complete details.
| Wipe Sampler/Sampling media | |
|---|---|
| Bulk Method |
| Device | |||||
|---|---|---|---|---|---|
| Model/Type | |||||
|
Sampling information (see manufacturer instructions) |
|
OSHA PEL
8-hour TWA (ST) STEL (C) Ceiling Peak |
NIOSH REL
Up to 10-hour TWA (ST) STEL (C) Ceiling |
ACGIH TLV©
8-hour TWA (ST) STEL (C) Ceiling |
|||||
|---|---|---|---|---|---|---|---|
| PEL-TWA |
3 ppm (2 mg/m³) |
REL-TWA |
3 ppm (2 mg/m³) |
TLV-TWA |
0.5 ppm [2004] |
PEL-TWA |
0.4 ppm (0.33 mg/m³) |
| PEL-STEL | REL-STEL | TLV-STEL | PEL-STEL |
1 ppm (0.83 mg/m³) |
|||
| PEL-C | REL-C |
6 ppm (5 mg/m³) [15 minutes] |
TLV-C |
2 ppm [2004] |
PEL-C | ||
| Skin notation |
N |
Skin notation |
Y |
Skin notation |
Y |
Skin notation |
Y |
| Notes: | Notes: |
Notes:
BEI® |
Notes: | ||||
| Health factors: See NIH-NLM PubChem. | IDLH |
30 ppm |
|||||
| Carcinogenic classifications: Not listed | Notes: | ||||||
|
AIHA emergency response planning guidelines - ERPG-1/ERPG-2/ERPG-3:
2 ppm/20 ppm/50 ppm |
|||||||
Additional Resources and Literature References
|
NOAA: CAMEO Chemicals - Hydrofluoric acid, solution NIOSH: Pocket Guide to Chemical Hazards - Hydrogen fluoride Literature References
|
Last Updated Date : 12/31/2020